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  • 1990-1994  (3.951)
  • 1965-1969  (1.651)
  • 1993  (3.951)
  • 1966  (1.651)
  • Life and Medical Sciences  (2.669)
  • General Chemistry  (2.412)
  • Computational Chemistry and Molecular Modeling  (478)
  • Cerebellum
  • Proteins
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  • 1990-1994  (3.951)
  • 1965-1969  (1.651)
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  • 1
    Digitale Medien
    Digitale Medien
    The distribution of amyloid plaques in the cerebellum and brain stem in Down's syndrome and Alzheimer's disease: a light microscopical analysis (1993)
    Springer
    Acta neuropathologica 85 (1993), S. 542-552 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Alzheimer's disease ; Plaques ; Cerebellum ; Brain stem ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The distribution and severity of the neuropathological changes in 57 cases of Alzheimer's disease, and 11 patients with Down's syndrome were investigated with reference to the cerebellum: A modified silver stain and a monoclonal antibody raised against amyloid β-protein were used to identify amyloid plaques. The highest incidence of amyloid plaques in the cerebellum (93%) was found in the group of patients who developed dementia before 65 years of age. This figure dropped to 56% in those patients with dementia beginning after 75 years. In 37 of these cases the distribution of the pathological changes of the disease were also examined in the brain stem. The severity of the pathological changes in the cerebellum corresponded to the involvement of the brain stem nuclei with connections to the cerebellar cortex. The possibility that the disease process spreads to the cerebellum by involving the fibres from the brain stem is discussed with reference to previous anatomical and neurochemical studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00230495
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  • 2
    Digitale Medien
    Digitale Medien
    Radiosensitive populations and recovery in X-ray-induced apoptosis in the developing cerebellum (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 491-500 
    Details
    ISSN: 1432-0533
    Schlagwort(e): X-rays ; X-rays ; Vimentin ; Proliferating cell nuclear antigen ; Cerebellum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Sprague-Dawley rats received a single dose of 2 Gy X-rays at the age of 1 or 3 days and were killed at different intervals. Dying cells with the morphological characteristics of apoptosis appeared in the external and internal granular layers (EGL and IGL) and white matter (WM) of the cerebellum, mainly 3–6 h after irradiation, and decreased thereafter to reach normal values between 48 h and 5 days later. This process was curbed by the injection of cycloheximide at a dose of 1 μg/g body weight. In addition, the number of mitoses in EGL rapidly decreased after irradiation and did not reach normal values until a few days later. Proliferating cell nuclear antigen (PCNA)-immunoreactive cells, which were chiefly found in EGL but also in IGL and WM, dramatically decreased in number from 3 to 48 h after irradiation. PCNA-immunoreactive cells reappeared and reached age-matched values in the following days. Hu (considered as an early neuronal marker) and vimentin immunocytochemistry disclosed that Hu-nonreactive cells in the upper level of EGL, Hu-immunoreactive cells in the inner level of EGL, Bergmann glia and many astrocytes in WM, as well as many non-typified cells in WM, were radiosensitive populations, whereas Purkinje cells were not. The present results indicate that irradiation at P1 or P3 blocks mitosis in EGL and kills sensitive cells mainly in the late G1 and S phases of the cell cycle, probably by apoptosis through a protein synthesis-mediated process. Radiosensitive cells are germinal cells and neuroblasts in EGL, Bergmann glia, astrocytes in WM, and non-typified cells, probably glial cell precursors, in WM. Surviving cells in EGL and PCNA-immunoreactive cells in other cortical layers and white matter reconstitute the cerebellum following a single dose of X-rays.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228585
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  • 3
    Digitale Medien
    Digitale Medien
    An analysis of HRP-filled basket cell axons in the cat's cerebellum (1993)
    Springer
    Anatomy and embryology 188 (1993), S. 299-305 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Pinceau ; HRP ; Cerebellum ; Purkinje cell ; Tendril collaterals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The axons of basket cells course horizontally within the lower molecular layer of the cerebellar cortex and give rise to three types of axon collaterals. One collateral distributes around the somata and axon hillocks of Purkinje cells, forming a complex pericellular basketlike formation or “pinceau”. The other two axonal specializations have the form of beaded tendrils, but differ in their origin and laminar distribution. In the previous paper, the morphometry and configuration of these axonal branches were described. In the present account, their synaptic relationships are analyzed based on serial section analysis and computer reconstructions. Our data indicate that: (1) Purkinje cells receive descending collaterals from more than one basket cell; (2) the contribution of the descending collaterals to individual pinceau is not uniform; Purkinje cells located close to the basket cell of origin receive a greater number of descending collaterals when compared to Purkinje cells located more distally; (3) few synaptic junctions are formed by the descending collaterals within the pinceaux; (4) beaded tendrils make synaptic contacts with the somata and dendrites of Purkinje cells, and (5) the horizontal axon forms synaptic junctions with the dendritic shafts and spiny branchlets of Purkinje cells. Functional considerations of these synaptic relationships are discussed in the light of the classic concept of off-beam inhibition mediated by basket cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00188220
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  • 4
    Digitale Medien
    Digitale Medien
    Infantile cerebello-optic atrophy (1993)
    Springer
    Acta neuropathologica 85 (1993), S. 241-247 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Cerebellum ; Granule cells ; Purkinje cells ; Optic atrophy ; Infantile spasms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Uniform neuropathological changes are described in eight cases of the progressive encephalopathy syndrome with edema, hypsarrhythmia and optic atrophy (PEHO syndrome). Two of the autopsied patients were sisters and two other cases were familial. Macroscopically, cerebral and pronounced cerebellar atrophy was seen, the essential histopathological lesions being confined to the cerebellar cortex and the optic nerve. There was a severe neuronal loss in the inner granular layer of the cerebellum. The Purkinje cells were relatively preserved in number although reduced in size, deformed and slightly disaligned. Their dendrites were hirozontally oriented and the proximal axons contained abundant torpedoes. The molecular layer was narrow. The optic nerves were atrophic. Serial neuroimaging studies showed that the disease process is operative during the postnatal period, although a prenatal onset cannot be excluded. An aberrant expression of immunoreactivity against the 200-kDa neurofilament polypeptide in Purkinje cell perikarya indicated disorganization of the cytoskeleton of these cells. The combination of clinical and pathological features of our patients differs from that observed in the few published cases of so-called primary degeneration of the granular layer. Infantile cerebello-optic atrophy, clinically characterized by seizures, blindness and early arrest in psychomotor development, thus seems to constitute a new autosomal recessive disorder.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227717
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  • 5
    Digitale Medien
    Digitale Medien
    Neuropathological study on cerebellum of macular mutant mouse heterozygote (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 411-417 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Macular mouse ; Heterozygote ; Cerebellum ; Neuropathology ; Menkes kinky hair disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The hemizygote of the macular mutant mouse is clinically, biochemically and neuropathologically similar to a patient with Menkes kinky hair disease. The heterozygote of this mutant mouse was biochemically and neuropathologically examined. The copper content in the brain decreased in comparison with that in the normal littermate, although it was more than that in the hemizygote. In the Golgi study, abnormal Purkinje cells with somal sprouts, thick stem dendrites and dendritic focal swellings, which were seen in the hemizygote, were not observed in the heterozygote. Ultrastructurally, abnormal mitochondria were seen in the Purkinje cells in the anterior and middle cerebellar lobe of the heterozygote. Histochemically, cytochrome c oxidase activity decreased, especially at the anterior lobe in the cerebellar cortex of the heterozygote. This activity, as indicated by staining intensity, was in between that in the normal littermate and that in the hemizygote. The heterozygote did not show a mosaic pattern in the distribution of these neuropathological changes, although this mutant mouse shows x-linked recessive inheritance. Thus, our results lead to the conclusion that the neuropathological changes observed in this mutant mouse do not result directly from an abnormal gene in the Purkinje cell, but from the secondary effects subsequent to presumptive copper deficiency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228573
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  • 6
    Digitale Medien
    Digitale Medien
    Activity of neurons in the beta nucleus of the inferior olive of the rabbit evoked by natural vestibular stimulation (1993)
    Springer
    Experimental brain research 94 (1993), S. 203-215 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cerebellum ; HRP ; Single unit recording ; Vestibular stimulation ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The inferior olive (IO) appears to be organized functionally in discrete subnuclei that receive transmitter-specific inputs. In particular, the IO receives a GABAergic input that is most densely concentrated in the β -nucleus. In this experiment, we examined the functional specificity of neurons in the β -nucleus of the IO of rabbits by recording their activity during natural vestibular and optokinetic stimulation. Rabbits were anesthetized and positioned in a triaxial servo- controlled rate table with the head fixed at the center of rotation. Contour-rich visual stimuli were rear-projected onto a 70 deg tangent screen and moved at constant velocities. Recording sites in the β -nucleus were verified by subsequent histological analysis of marking microlesions. Neurons in the β -nucleus responded to roll vestibular stimulation about the longitudinal axis. These neurons were excited when the rabbit was rolled onto the side which was contralateral to the recording site, and inhibited when the rabbit was rolled ipsilaterally. Thirty-eight of the 75 β -nucleus neurons that were responsive to roll vestibular stimulation also responded to static tilt, indicating an otolithic as well as a vertical semicircular canal origin of the vestibular input. The modulated activity of none of the neurons could be attributed to stimulation of the horizontal semicircular canals. All the recorded neurons were found in a region of the β -nucleus that was retrogradely labeled following HRP injections into the cerebellar nodulus. Using a “null point” technique, we found that there was a differential projection of information from the anterior and posterior semicircular canals onto to the β -nucleus. Stimulation of the ipsilateral anterior-contralateral posterior semicircular canals modulates activity of the neurons in the caudal 500 μm of the β -nucleus. Stimulation of the ipsilateral posterior-contralateral anterior semicircular canals modulates activity of neurons located more rostrally. β -nucleus neurons and the olivocerebellar circuits in which they participate may constitute an important pathway for the control and adaptive modification of postural reflexes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00230288
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  • 7
    Digitale Medien
    Digitale Medien
    Optokinetic-vestibular interaction in patients with increased gain of the vestibulo-ocular reflex (1993)
    Springer
    Experimental brain research 97 (1993), S. 334-342 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cerebellum ; Optokinetic afternystagmus ; Velocity storage ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We studied optokinetic nystagmus (OKN), optokinetic afternystagmus (OKAN) and visual-vestibular interaction in five patients with markedly elevated vestibulo-ocular reflex (VOR) gain due to cerebellar atrophy. All had impaired smooth pursuit, decreased initial slow phase velocity of OKN, and impaired ability to suppress the VOR with real or imagined targets. OKN slow phase velocity gradually built up over 25–45 s, reaching normal values for low stimulus velocities (≤30 deg/s). Initial velocity of OKAN was increased, but the rate of decay of OKAN was normal. These findings can be explained by models that include separate velocity storage and variable gain elements shared by the vestibular and optokinetic systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228703
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  • 8
    Digitale Medien
    Digitale Medien
    The olivocerebellar projection in normal (+ / +), heterozygous weaver (wv/ +), and homozygous weaver (wv/wv) mutant mice: comparison of terminal pattern and topographic organization (1993)
    Springer
    Experimental brain research 95 (1993), S. 187-201 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Inferior olivary complex ; Cerebellum ; Parasagittal organization ; Autoradiography ; WGA-HRP ; Mouse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Olivocerebellar organization and topography were analyzed in adult normal (+ / +), heterozygous weaver (wv/+), and homozygous weaver (wv/wv) mutant mice. The two genotypes (wv/+ and wv/wv) of the weaver mutant present a gradation of abnormal cerebellar morphology. Purkinje cell (PC) ectopia ranges from mild (wv/+) to moderate (wv/wv), and regional PC loss is also graded in the two types. To determine olivocerebellar organization and topography, tritiated amino acids were placed into different regions of the inferior olivary complex (IO) in normal, heterozygous, and homozygous weaver mice. Despite some PC loss and ectopia, olivocerebellar fiber (OCF) terminals in both homozygous and heterozygous weaver mice have an orthogonal distribution and topography similar to that seen in normal mice. Differences in OCF termination, such as an increased density of OCF terminal label in the lower portion of the molecular layer, the PC, and granule cell layers, are seen in homozygous weaver mice. In some heterozygous weaver and normal cases, multiple injections labeling most IO cells on one side of the IO resulted in continuous OCF terminal labeling in many regions of the contralateral cerebellar cortex, suggesting that all PCs receive OCF input. Retrograde analysis involving injections of horseradish peroxidase conjugated to wheat germ agglutinin into different mediolateral cerebellar regions in homozygous weaver mice further demonstrates a generally normal olivocerebellar topography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00229778
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  • 9
    Digitale Medien
    Digitale Medien
    Role of the cerebellum in visuomotor coordination (1993)
    Springer
    Experimental brain research 94 (1993), S. 478-488 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Eye-arm coordination ; Cerebellum ; Visual feedback ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The initiation of coupled eye and arm movements was studied in six patients with mild cerebellar dysfunction and in six age-matched control subjects. The experimental paradigm consisted of 40 deg step-tracking elbow movements made under different feedback conditions. During tracking with the eyes only, saccadic latencies in patients were within normal limits. When patients were required to make coordinated eye and arm movements, however, eye movement onset was significantly delayed. In addition, removal of visual information about arm versus target position had a pronounced differential effect on movement latencies. When the target was extinguished for 3 s immediately following a step change in target position, both eye and arm onset times were further prolonged compared to movements made to continuously visible targets. When visual information concerning arm position was removed, onset times were reduced. Eye and arm latencies in control subjects were unaffected by changes in visual feedback. The results of this study clearly demonstrate that, in contrast to earlier reports of normal saccadic latencies associated with cerebellar dysfunction, initiation of both eye and arm movements is prolonged during coordinated visuomotor tracking thus supporting a coordinative role for the cerebellum during oculo-manual tracking tasks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00230206
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  • 10
    Digitale Medien
    Digitale Medien
    Subtotal agenesis of the cerebellum in an adult (1993)
    Springer
    Neuroradiology 35 (1993), S. 286-287 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Magnetic resonance imaging ; Cerebellum ; Cerebellar agenesis ; Cerebellar anomaly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe a 58-year-old asymptomatic woman with subtotal developmental absence of the cerebellum. MRI evaluation showed minute remnants of cerebellar tissue corresponding to the anterior quadrangular lobules. These findings identified the anomaly as subtotal cerebellar agenesis, and excluded other diagnostic possibilities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00602617
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  • 11
    Digitale Medien
    Digitale Medien
    Peptide models II. Intramolecular interactions and stable conformations of glycine, alanine, and valine peptide analogues (1993)
    Springer
    Theoretical chemistry accounts 85 (1993), S. 189-197 
    Details
    ISSN: 1432-2234
    Schlagwort(e): Peptide models ; Amino acids ; Conformations, stable ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The stable conformations of N and C protected amino acids of the type: HCONH-CHR-CONH2 of glycine,l-alanine andl-valine have been obtained by fully optimizedab-initio computations with a 3–21G basis set. An original procedure has been devised to extract the side-chain/backbone interaction energy and the backbone and side-chain distortion energies. This enables us to analyze the stabilization/destabilization effects introduced by the side-chain in terms of electrostatic, induction and steric hindrance contributions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01374587
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  • 12
    Digitale Medien
    Digitale Medien
    Observation of intersubunit NOEs in a dimeric P22 Mnt repressor mutant by a time-shared [15N, 13C] double half-filter technique (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 709-714 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Isotope half-filter ; Triple-resonance NMR ; Proteins ; Intersubunit NOEs ; Mnt repressor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary A time-shared [15N, 13C] half-filter technique is presented, which can be used to study proton-proton NOEs between biomolecules. The filter is demonstrated in a 2D [15N, 13C] double filtered NOESY experiment of a dimeric Mnt repressor mutant consisting of completely [15N, 13C] labeled monomer and unlabeled monomer. The benefit of this combined [15N, 13C] half-filter is that a single NMR experiment can be designed that yields all NOE interactions between labeled and unlabeled protons ((13C, 14N/12C), (15N, 14N/12C), (12C, 15N/13C) and (14N, 15N/13C)) in the protein, where conventional half-filters would require at least three separate NMR experiments to obtain these NOEs. The intermonomer NOEs of the Mnt mutant confirmed the secondary structure of the DNA-binding domain as an antiparallel β ribbon, formed from an N-terminal segment contributed by each monomer. Moreover, several intersubunit NOEs were characterized in the C-terminal part of the Mnt mutant for which no structural data is available yet.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198373
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  • 13
    Digitale Medien
    Digitale Medien
    Resolution and sensitivity enhancement of heteronuclear correlation for methylene resonances via 2H enrichment and decoupling (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 701-708 
    Details
    ISSN: 1573-5001
    Schlagwort(e): NMR ; Heteronuclear correlation ; Isotope labeling ; Proteins ; Methylene resonances
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Monodeuterated methylene positions exhibit substantially superior spectral characteristics in 1H−13C correlation experiments as compared to diprotio signals. A combination of 2H decoupling and multiplet editing of HMQC and HSQC experiments provides resolution enhancement for both stereoselective and random fractionally deuterated samples. For HMQC experiments with [2-2Hr, 2-13C]glycine-labeled E. coli thioredoxin (11.7 kDa), 3-fold increases in both 1H and 13C resolution result in a complementary 9-fold enhancement in sensitivity. Owing to a smaller improvement in 13C resolution, the corresponding enhancements for the HSQC experiment are 2-fold less.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198372
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  • 14
    Digitale Medien
    Digitale Medien
    A simple and sensitive experiment for measurement of JCC couplings between backbone carbonyl and methyl carbons in isotopically enriched proteins (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 487-493 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Carbon-carbon J coupling ; Proteins ; Two-dimensional NMR ; χ1 Angle ; Stereospecific assignment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary A simple 2D difference experiment is described that allows quantitative measurement of 13C−13C J couplings between backbone carbonyl and side-chain carbons. Precise 3JCC values were measured from data recorded in just 2 h for a 1-mM solution of the 20-kD complex between the protein calmodulin and a 26-residue synthetic peptide. The J couplings aid in determining the χ1 angles of valine, isoleucine and threonine residues, and in making stereospecific assignments of the Val Cγ methyl groups. Error analysis indicates that the uncertainty in the derived J couplings is generally less than ca. 0.3 Hz.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00176014
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  • 15
    Digitale Medien
    Digitale Medien
    3D Triple-resonance NMR techniques for the sequential assignment of NH and 15N resonances in 15N- and 13C-labelled proteins (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 113-120 
    Details
    ISSN: 1573-5001
    Schlagwort(e): 3D NMR ; J connectivity ; Sequential assignment ; Isotope labelling ; Proteins ; Ribonuclease T1
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Two new 3D 1H-15N-13C triple-resonance experiments are presented which provide sequential cross peaks between the amide proton of one residue and the amide nitrogen of the preceding and succeeding residues or the amide proton of one residue and the amide proton of the preceding and succeeding residues, respectively. These experiments, which we term 3D-HN(CA)NNH and 3D-H(NCA)NNH, utilize an optimized magnetization transfer via the 2JNCα coupling to establish the sequential assignment of backbone NH and 15N resonances. In contrast to NH-NH connectivities observable in homonuclear NOESY spectra, the assignments from the 3D-H(NCA)NNH experiment are conformation independent to a first-order approximation. Thus the assignments obtained from these experiments can be used as either confirmation of assignments obtained from a conventional homonuclear approach or as an initial step in the analysis of backbone resonances according to Ikura et al. (1990) [Biochemistry, 29, 4659–4667]. Both techniques were applied to uniformly 15N- and 13C-labelled ribonuclease T1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00242479
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  • 16
    Digitale Medien
    Digitale Medien
    Computer-assisted assignment of multidimensional NMR spectra of proteins: Application to 3D NOESY-HMQC and TOCSY-HMQC spectra (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 245-251 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Multidimensional NMR ; Computer-assisted NMR assignment ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary An algorithm based on the technique of combinatorial minimization is used for the semi-automated assignment of multidimensional heteronuclear spectra. The program (ALFA) produces the best assignment compatible with the available input data. Even partially misleading or missing data do not seriously corrupt the final assignment. Ambiguous sequences of the possible assignment and all alternatives are indicated. The program can also use additional non-spectroscopic data to assist in the assignment procedure. For example, information from the X-ray structure of the protein and/or information about the secondary structure can be used. The assignment procedure was tested on spectra of mucous trypsin inhibitor, a protein of 107 residues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00178267
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  • 17
    Digitale Medien
    Digitale Medien
    A simple way for sequential assignment in isotopically enriched proteins using a H(N)CACO correlation (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 233-237 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Triple resonance ; Sequential assignment ; Isotope labeling ; Mannose permease ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary A simplified scheme for sequential assignment in isotopically enriched proteins is presented. It is based on the standard triple resonance experiments HNCO, HN(CO)CA, HNCA and a modified H(N)CACO correlation, in which both of the HN connectivities to the CA/C′ pair of residue i and i-1 are observed. The H(N)CACO was tested on uniformly 13C/15N enriched P13 domain of mannose permease (31 kDa).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00178265
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  • 18
    Digitale Medien
    Digitale Medien
    Protein fold recognition (1993)
    Springer
    Journal of computer aided molecular design 7 (1993), S. 439-456 
    Details
    ISSN: 1573-4951
    Schlagwort(e): Proteins ; Protein structure ; Protein folding ; Tertiary structure prediction ; Computer algorithms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An important, yet seemingly unattainable, goal in structural molecular biology is to be able to predict the native three-dimensional structure of a protein entirely from its amino acid sequence. Prediction methods based on rigorous energy calculations have not yet been successful, and best results have been obtained from homology modelling and statistical secondary structure prediction. Homology modelling is limited to cases where significant sequence similarity is shared between a protein of known structure and the unknown. Secondary structure prediction methods are not only unreliable, but also do not offer any obvious route to the full tertiary structure. Recently, methods have been developed whereby entire protein folds are recognized from sequence, even where little or no sequence similarity is shared between the proteins under consideration. In this paper we review the current methods, including our own, and in particular offer a historical background to their development. In addition, we also discuss the future of these methods and outline the developments under investigation in our laboratory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02337560
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  • 19
    Digitale Medien
    Digitale Medien
    Efficient methods for obtaining phase-sensitive gradient-enhanced HMQC spectra (1993)
    Springer
    Journal of biomolecular NMR 3 (1993), S. 215-224 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Pulsed field gradients ; HMQC ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Three improved versions of the gradient-enhanced HMQC experiment are presented which yield phase-sensitive spectra with increased sensitivity compared to the recently described field-gradient HMQC schemes. The first method uses a complex linear back-prediction in order to generate the FIDs at the t1=0. With this approach, refocusing pulses on the heteronucleus are not necessary. The sequence is especially useful for larger proteins with short relaxation times for the coherences that evolve during t1. In the other two methods lower and shorter gradient pulses or asymmetric gradients are used to optimize sensitivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00178263
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  • 20
    Digitale Medien
    Digitale Medien
    Serotonergic inhibition of the mossy fibre—granule cell glutamate transmission in rat cerebellar slices (1993)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 348 (1993), S. 347-351 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Cerebellum ; Mossy fibres ; Granule cells ; Glutamate release ; 5-HT ; 5-HT2 receptors ; cGMP ; Glutamate receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The glutamatergic mossy fibre → granule cell pathway has been investigated in rat cerebellar slices. Exposure to 35 mM KCI, a concentration of K+ known to elicit Ca2+-dependent releases of excitatory amino acids from cerebellar slices, raised cGMP levels. The cGMP response was decreased in a concentration-dependent manner by D-(−)-2-amino-5-phosphonopentanoic acid (D-AP5) and by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) indicating the involvement of ionotropic glutamate receptors of both the N-methyl-D-aspartate (NMDA) and the non-NMDA type. The K+-evoked production of cGMP was potently inhibited (EC50 = 1.21 nM) by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a selective 5-HT2 receptor agonist. The effect of DOI (0.01 μM) was antagonized by 0.03 μM of the 5-HT2 receptor antagonists ketanserin and methiothepin. At concentrations higher than 0.1 μM, both antagonists increased on their own the cGMP response elicited by high-K+. This effect was insensitive to tetrodotoxin. It had been previously shown that rat mossy fibre endings release glutamate upon depolarization and that such release can be inhibited by activation of 5-HT2 receptors sited on the mossy fibre endings. Altogether the available data suggest the following conclusions: (a) the glutamate/aspartate endogenously released in cerebellar slices during K+ depolarization increase cGMP synthesis through the activation of both NMDA and non-NMDA receptors; (b) a portion of the cGMP response can be prevented by 5-HT2 receptor activation and may reflect the activity of the mossy fibre-granule cell pathway. Thus serotonin is likely to exert a potent inhibitory control of the excitatory mossy fibre input to the cerebellum by acting at receptors of the 5-HT2 type.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00171332
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  • 21
    Digitale Medien
    Digitale Medien
    Salt tolerance in Lycopersicon species. I. Character definition and changes in gene expression (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 737-743 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Salt tolerance ; Lycopersicon ; Yield ; Proteins ; C4 species
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Salt tolerance defined in terms of fruit yield under different NaCl concentrations (171.1 and 325.1 mM) is analyzed in 11 lines belonging to: Lycopersicon esculentum, L. cheesmanii, L. chmielewski, L. peruvianum and L. pimpinellifolium. Four L. pimpinellifolium lines and two L. cheesmanii lines tolerated the 171.1mM treatment; the latter species even tolerates 325.1 mM of NaCl. Changes in gene expression induced by salt treatment were also investigated by studying anther and leaf zymograms for L. esculentum and one salt-tolerant L. pimpinellifolium line, and leaf proteinograms for all lines. Changes in leaf PRX and MDH enzymatic systems were detected, mainly in the salt-sensitive genotype (L. esculentum). Four saltrelated peptides from 14 500 to 40 000 daltons were found. A polyclonal antibody raised against one of these peptides (number 2), also binds another peptide, named 2′, of much higher molecular weight, present both in control and salt-tolerant L. cheesmanii lines at the end of 171.1 mM treatment. The xero-halophyte shrub Atriplex halimus also showed a likely 2′-homologous peptide with this treatment, while its counterpart C3 species A. triangularis did not.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222664
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  • 22
    Digitale Medien
    Digitale Medien
    Quantitative genetic studies of A/B zeins using a new model to test non-allelic interactions (1993)
    Springer
    Theoretical and applied genetics 87 (1993), S. 33-37 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Zein ; Zea mays L. ; Corn ; Genetic linkages ; RP-HPLC ; Proteins ; Prolamins ; Inheritance ; Quantitation ; Model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A genetic model developed by Bogyo et al. (1988) for quantitatively inherited triploid endosperm characters (an extension of the well-known Mather-Jinks model) is not well-suited for estimating epistatic interaction effects because it requires the assumption that, in segregating loci, all alleles positively affecting a particular character are in one of the inbred parental lines. To better explain zein inheritance in maize, a new model was developed not relying on this assumption. This model was tested by quantitative analysis of A/B zeins, the predominant prolamin storage proteins of maize, using reversed phase high-performance liquid chromatography of two inbred lines, their reciprocal F1 crosses, the F2 generation, backcrosses, and reciprocal backcrosses to both parent lines. The model required epistatic components to be included for an excellent fit for most protein peaks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223740
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  • 23
    Digitale Medien
    Digitale Medien
    Possible multiple evolution of indirect telencephalo-cerebellar pathways in teleosts: studies in Carassius auratus and Pantodon buchholzi (1993)
    Springer
    Cell & tissue research 274 (1993), S. 447-455 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cerebellum ; Evolution ; Brain, vertebrate ; Pons ; Telencephalon ; Carassius auratus, Pantodon buchholzi (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Among vertebrates, telencephalo-pontine systems exist only in birds and mammals. However, three nuclei in the diencephalon and mesencephalon of teleost fishes have been indicated — analogous to the pons — to represent relay stations between telencephalon and cerebellum. Since two of these nuclei (dorsal preglomerular nucleus, dorsal tegmental nucleus) have only been described in the highly derived, electrosensory mormyrids, we investigated telencephalic connections in two nonelectrosensory teleosts, the goldfish Carassius auratus and the freshwater butterflyfish Pantodon buchholzi, and cerebellar connections only in the latter species, since for C. auratus these connections are already established. Horseradish peroxidase tracing reveals that C. auratus has a dorsal tegmental nucleus and a paracommissural nucleus both of which are telencephalo-recipient and project to the cerebellum, and that P. buchholzi has a dorsal preglomerular nucleus with such connections. These results extend our knowlegde of the distribution and, therefore, the phylogeny of telencephalo-cerebellar systems in teleosts. Similar to tetrapods, teleosts appear to have developed telencephalo-cerebellar systems several times independently.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00314541
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  • 24
    Digitale Medien
    Digitale Medien
    The effect of rate of eruption on periodontal ligament glycosylaminoglycan content and enamel formation in the rat incisor (1993)
    Springer
    Cell & tissue research 274 (1993), S. 413-419 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Periodontium ; Eruption ; Enamel ; Glycosylaminoglycans ; Proteins ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The rate of eruption of rat mandibular incisors was either increased by cutting one tooth out of occlusion or eliminated by means of pinning. The effects of such changes in eruption rate on the sulphated glycosylaminoglycan content of the periodontal ligaments was analysed. The length of the enamel secretory zone and the composition of the developing enamel matrix protein was also compared. Sulphated glycosylaminoglycan content of the periodontal ligament increased fourfold (P〈0.001) during accelerated eruption but decreased to a corresponding extent (P〈0.001) in the absence of eruption, when compared with controls. The length of the enamel secretory zone was also significantly reduced in the immobilised teeth, although the protein content was similar compared with controls. The results demonstrate the differential response to varied eruption rates of the periodontal ligament and enamel, particularly in respect of the extracellular matrix. The data are consistent with the view that the ground substance of the periodontal ligament plays a role in the generation of the eruptive force.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318760
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  • 25
    Digitale Medien
    Digitale Medien
    A micro-scale method employing surface plasmon resonance detection for the determination of conditions for immunoaffinity chromatography of proteins (1993)
    Springer
    Chromatographia 35 (1993), S. 45-49 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Immunoaffinity chromatography ; Proteins ; Surface plasmon resonance detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The BIAcoreTM Biosensor System utilizes a detection principle known as Surface Plasmon Resonance (SPR) which, in simple terms, detects changes in the refractive index of a solution in contact with a gold film. The gold film is surface modified with carboxymethylated dextran to produce a hydrophillic matrix onto which macromolecules may be covalently immobilized. In this respect, the BIAcoreTM is similar to any other insoluble matrix, such as a chromatographic support. The SPR detection principle, however, allows one to directly ‘visualize’ the interaction under study, in real time and without the need for reporter molecules such as enzyme-labels. In addition, the very small sample requirements, automated robotics unit and ease of data analysis suggest the potential use of the BIAcoreTM instrumentation for assay development and possibly process development, especially where bio-specific interactions such as immunoaffinity chromatography are used as a step in the process. In this report, we demonstrate the use of the BIAcoreTM SPR detector for the micro-scale determination of conditions for immunoaffinity chromatography of soluble complementreceptor 1, sCR1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02278555
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  • 26
    Digitale Medien
    Digitale Medien
    Drug transport across the blood-brain barrier (1993)
    Springer
    Pharmacy world & science 15 (1993), S. 2-9 
    Details
    ISSN: 1573-739X
    Schlagwort(e): Biological transport ; Blood-brain barrier ; Cell membrane permeability ; Cerebrospinal fluid ; Peptides ; Prodrugs ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract This is the third part of a review on the transport of drugs across the blood-brain barrier. In the first two parts, the anatomical and physiological aspects and the various techniques that can be used to study blood-brain transport have been discussed and reviewed. This third part focuses specifically on the mechanisms that are involved in drug transport across the blood-brain barrier. In addition, the opportunities to improve drug transport into the brain will be reviewed. Emphasis is on the transport of peptides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02116163
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  • 27
    Digitale Medien
    Digitale Medien
    Drug targeting to the kidney with low molecular weight proteins (1993)
    Springer
    Pharmacy world & science 15 (1993), S. 276-278 
    Details
    ISSN: 1573-739X
    Schlagwort(e): Drug targeting ; Kidney ; Lysosomes ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01871130
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  • 28
    Digitale Medien
    Digitale Medien
    Nutrient composition and electrophoretic pattern of protein in two distinct types of phalsa (Grewia subinequalis DC) (1993)
    Springer
    Plant foods for human nutrition 44 (1993), S. 255-260 
    Details
    ISSN: 1573-9104
    Schlagwort(e): Phalsa ; Physical characters ; Sugars ; Proteins ; Electrophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Two distinct types, i.e. tall and dwarf types of phalsa, were studied for the differences in their physical parameters, chemical compositions and electrophoretic patterns of seed proteins by SDS-PAGE. The two types did not show any remarkable variation in their fruit weight, edible portion, seed weight and juice yield. Tall type had higher content of reducing sugars whereas total and non-reducing sugars were higher in dwarf one. Qualitative analysis revealed the presence of sucrose and fructose in both the types whereas glucose was present only in tall one. Observed marked variations in the protein content of the fruit could be due to the differences in protein content of the seed rather than that of the pulp. Electrophoretic pattern of seed proteins revealed the complete absence of two protein bands of molecular weight 37, and 59 kD from the dwarf type.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01088320
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  • 29
    Digitale Medien
    Digitale Medien
    Depletion of polyamines prevents the neurotrophic activity of the GABA-agonist THIP in cultured rat cerebellar granule cells (1993)
    Springer
    Neurochemical research 18 (1993), S. 153-158 
    Details
    ISSN: 1573-6903
    Schlagwort(e): Cerebellum ; granule cells ; polyamines ; DFMO ; GABA ; morphological development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Effects of polyamine depletion by α-difluoromethylornithine (DFMO) were studied on the GABA-agonist mediated enhancement of the morphological development of cultured rat cerebellar granule cells. An increase in the number of neurite extending cells and in the cytoplasmic density of organelles relevant for protein synthesis was observed upon culturing in the presence of 4,5,6,7-tetrahydro-isoxazolo[5,4-c]pyridin-3-ol (THIP) for 4 days. The intracellular concentrations of putrescine, spermadine, and spermine in these cultures were similar to the concentrations of the polyamines observed in cultures grown in a plain culture medium for 1, 2, 3 or 4 days, respectively. Upon culturing in the simultaneous presence of THIP and DFMO, the concentrations of putrescine and spermadine were reduced to less than 20% of the levels in the controls. This depletion was associated with a severely impaired morphological development of the granule cell cultures. Thus, the number of neurite extending cells was reduced to 50% of the number in the control cultures upon culturing in the presence of DFMO alone or in combination with THIP. Moreover, the THIP mediated increase in the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus and different types of vesicles was prevented by the exposure to DFMO.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01474678
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  • 30
    Digitale Medien
    Digitale Medien
    Variations in the distribution of motor end-plates in the avian pectoralis (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 65-88 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Most avian muscles consist of serially arranged, overlapping fibers that do not extend the length of the muscle. This condition appears to be plesiomorphic with respect to diapsid reptiles. The presence of this serialfibered architecture is evidenced by bands of stained motor end-plates (meps) perpendicular to the columns of fibers and dividing each column into a series of “segments.” The avian pectoralis was chosen for a study of variation in the distribution of meps within a single muscle. We report the interspecific variation for 158 specimens in 63 species. We also use additional specimens to examine intraspecific variation.Setting aside hummingbirds, which have an unique and clearly derived condition, the number of mep bands along a column of fibers near the shoulder falls within a remarkably small range. The number of segments is not obviously related to phylogenetic relatedness or to any characteristic of flight or ecology and is only slightly related to size. The largest specimens do average more segments per column, but there are no trends among small to medium-sized species, suggesting that there is an upper limit to fiber length. However, the shape of the sternum and pattern of connective tissue in the pectoralis alleviate the need for additional fibers in many large birds. These findings suggest that the architecture of the avian pectoralis is subject to some as yet unexplained selection that stabilizes the number of myofibers and/or motor neurons. The findings provide few clues as to whether the significant factors are phylogenetic, functional, ontogenetic, or some combination of these. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150105
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  • 31
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150201
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  • 32
    Digitale Medien
    Digitale Medien
    Morphological and functional bases of durophagy in the queen triggerfish, Balistes vetula (Pisces, tetraodontiformes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 101-118 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Tetraodontiform fishes are characterized by jaws specialized for powerful biting and a diet dominated by hard-shelled prey. Strong biting by the oral jaws is an unusual feature among teleosts. We present a functional morphological analysis of the feeding mechanism of a representative tetraodontiform, Balistes vetula. As is typical for the order, long, sharp, strong teeth are mounted on the short, robust jaw bones of B. vetula. The neurocranium and suspensorium are enlarged and strengthened to serve as sites of attachment for the greatly hypertrophied adductor mandibulae muscles. Electromyographic recordings made from 11 cranial muscles during feeding revealed four distinct behaviors in the feeding repertoire of B. vetula. Suction is used effectively to capture soft prey and is associated with a motor pattern similar to that reported for many other teleosts. However, when feeding on hard prey, B. vetula directly bit the prey, exhibiting a motor pattern very different from that of suction feeding. During buccal manipulation, repeated cycles of jaw opening and closing (biting) were coupled with rapid movement of the prey in and out of the mouth. Muscle activity during buccal manipulation was similar to that seen during bite-captures. A blowing behavior was periodically employed during prey handling, as prey were forcefully “spit out” from the mouth, either to reposition them or to separate unwanted material from flesh. The motor pattern used during blowing was distinct from similar behaviors described for other fishes, indicating that this behaviors may be unique to tetraodontiforms. Thus B. vetula combines primitive behaviors and motor patterns (suction feeding and buccal manipulation) with specialized morphology (strong teeth, robust jaws, and hypertrophied adductor muscles) and a novel behavior (blowing) to exploit armored prey such as sea urchins molluscs, and crabs. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150202
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  • 33
    Digitale Medien
    Digitale Medien
    Early development of the chick embryo (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 165-182 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ultrastructure of the early chick embryo was investigated, using scanning (SEM) and transmission electron microscopy (TEM). Eggs were obtained from the shell gland by injecting hens intravenously with a synthetic prostaglandin or arginine vasopressin. Embryos were examined during late cleavage (stages IV-VI, Eyal-Giladi and Kochav, '76), formation of the area pellucida (stages VII-XI), and formation of the hypoblast (stages X-XIV). SEM highlighted the reduction in cell number at the underside of the embryo during formation of the area pellucida although it became apparent that the thickness of the embryo is not reduced to a single layer of cells at stage X. In addition, blastomeres at the perimeter of embryos (stages V-VI) project filopodial extensions onto a smooth membrane that separates the sub-embryonic cavity from the yolk. During hypoblast formation, epiblast cells generate stellate projections at their basal aspect, thus providing a meshwork for the advancing secondary hypoblast cells. By stage XII the epiblast was one cell thick and reminiscent of a columnar epithelium when viewed transversely. Cells of the deep portion of the posterior marginal zone were distinguished morphologically in the stage XII embryo by their many cell surface projections and ruffled appearance. Blastomeres at the perimeter of stage V-VI embryos projected filopodial extensions onto a smooth membrane which separates the sub-embryonic cavity from the yolk. This membrane is presumed to be confluent with the cytolemma. Evidence is presented demonstrating the presence of intracellular membrane-bound droplets which are hypothesised to contain sub-embryonic fluid. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 41 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150205
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  • 34
    Digitale Medien
    Digitale Medien
    Land crabs with smooth lungs: Grapsidae, Gecarcinidae, and Sundathelphusidae ultrastructure and vasculature (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 245-260 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The highly terrestrial grapsids and gecarcinids and the amphibious sundathelphusids all have large, expanded branchial chambers. The lining of the branchial chambers is smooth and well vascularized, and it functions as a lung. The respiratory membrane and the cuticle lining the lung are extremely thin (200-350 nm). The blood vessels within the lung are formed from connective tissue cells supported by collagen fibres and lined by a basal lamina. The major vessels in the lung are embedded deep in the branchiostegite and lie just beneath the thick outer carapace. These vessels branch towards the respiratory membrane, where they eventually lose their connective tissue coverings to form thin, flattened lacunae directly below the respiratory epithelium. The lacunae (exchange sites) are bordered by specialized connective tissue cells, which either bear microvilli on their apical surface (fimbriated cells) or are very smooth. The respiratory circulation in the lung is very complex, with two portal systems present between the afferent and efferent systems, producing a total of three lacunal exchange beds. Portal systems increase the surface area available for gas exchange. The major distributing vessel in the lung is the branchiostegal vein, which runs along the inner margin of the branchiostegite. The main venous supplies come anteriorly from the infraorbital and ventral sinuses and posteriorly from the procardial sinus. The main collecting vessel is the pulmonary vein, which arises anteriorly and which runs around the ventral perimeter of the branchiostegite before emptying into the pericardial sinus. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 25 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150306
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  • 35
    Digitale Medien
    Digitale Medien
    Naturally occurring diblastodermic eggs in the annual fish Cynolebias: Implications for developmental regulation and determination (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 301-312 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Annual fish development differs from that of other teleosts because a phase of blastomere dispersion-reaggregation spatially and temporally separates epiboly from embryogenesis. The fate of dispersed blastomeres was assessed in diblastodermic eggs of the annual fishes Cynolebias whitei and C. nigripinnis. In typical teleosts, blastomere determination and the events of primary embryonic induction occur prior to or during epiboly, so diblastodermic eggs produce partially or completely duplicated embryos. In the diblastodermic eggs of Cynolebias, the two blastoderms are completely separate from the one cell stage to the high blastula. Blastoderm fusion begins during midepiboly. By the end of epiboly, blastoderm fusion has been completed, and the deep, embryo-forming blastomeres of both blastoderms have completely dispersed and intermingled to form a single cell population. A typical annual fish dispersed blastomere phase ensues. Blastomeres reaggregate into a single mass, in which one embryo develops. When hatched, the young fish have no obvious structural or functional abnormalities. We suggest that the dispersed blastomeres of annual fish eggs are equivalent and that induction or determination takes place within the reaggregate. Alternatively, dispersed cells are partially determined but highly regulative, so that, when two populations fuse, the cells sort out according to tissue type and form a single embryo. In either instance, the formation of a single, normal embryo seems to corroborate the hypothesis that the dispersed cell phase of annual fishes is an adaptation that prevents environmentally induced developmental defects. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150309
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  • 36
    Digitale Medien
    Digitale Medien
    Morphological analysis of tendinous structure in the American alligator jaw muscles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 171-181 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the American alligator, the jaw muscles show seven bundles of tendinous structure: cranial adductor tendon, mandibular adductor tendon, lamina anterior inferior, trap-shaped lamina lateralis, lamina intramandibularis, lamina posterior, and depressor mandibular tendon (originating from the musculus depressor mandibulae, m. pseudotemporalis, m. adductor mandibulae posterior, m. adductor mandibulae externus, m. intramandibularis, m. pterygoideus anterior, and m. pterygoideus posterior). These tendinous structures are composed of many collagen fibrils and elastic fibers; however, the distributions and sizes of the fibers in these tendinous components differ in comparison with those of other masticatory muscles. The differences of these properties reflect the kinetic forces or the stretch applied to each tendon by the muscle during jaw movements in spite of the simple tendon-muscle junctions. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170206
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  • 37
    Digitale Medien
    Digitale Medien
    The horizontal septum: Mechanisms of force transfer in locomotion of scombrid fishes (Scombridae, Perciformes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 183-204 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We describe the complex shapes of myomeres and myosepta in the mackerels and tunas (Scombridae: Teleostei), and we reveal the orientation of two major systems of collagen fibers in myosepta and horizontal septa with respect to points of attachment to skeleton and skin. Our goal is to identify the likely pathways of the transmission of muscle forces during locomotion. Our primary conclusions are (1) that the collagen fibers of myosepta, horizontal septa, and skin are the organs that transfer locomotor forces from the contraction of myomeres to the backbone and caudal fin during locomotion, and (2) that locomotor muscle pulls against a three-dimensional structure of tendons, septa, and skin that is kept in tension by the radial expansion of the contracting muscle. The main horizontal septum is formed by the convergence of myosepta and is likely to be the major transmitter of muscle force to the axial skeleton. The geometry of the myomeres, the position of red muscle, and particularly the geometric conformation of crossed-fiber arrays of collagen in the main horizontal septum suggest specific mechanisms for the transfer of muscle force to the backbone among scombrid fishes. Morphometrics and the construction of physical models help us to identify musculoskeletal mechanisms of locomotion, and we present two quantitative models of locomotor mechanics in fishes. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170207
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  • 38
    Digitale Medien
    Digitale Medien
    Oviductal morphology and eggshell formation in the lizard, Sceloporus woodi (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 205-217 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Despite a great deal of work in recent years on the structure of reptilian eggshells, few studies have examined the structure and regulation of the female reproductive tract in the formation of eggshell components, and none have examined the entire process from ovulation to oviposition. In this study, we examined oviductal structure in the oviparous lizard, Sceloporus woodi, followed changes in oviductal structure during gravidity, and determined uterine function in the formation of eggshell components. The endometrial glands of the uterus produce the proteinaceous fibers of the eggshell membrane mainly during the first 24 hours following ovulation, and the fibers are secreted intact and subsequently wrapped around the in utero eggs. Eggshell fibers of different thicknesses are layered around each egg, ranging from an inner layer of thick fibers that gradually become thinner medially and finally forms an outer layer of densely packed particulate matter. These changes in the fibrous layer are reflected by the thickness and length of fibers released from the endometrial glands. Calcium deposition occurs from 3 days following ovulation through day 14 (oviposition) and is accompanied by cellular changes in the luminal epithelium suggestive of secretory activity. Deposition of the eggshell components within the uterus occurs on all eggs simultaneously, rather than sequentially. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170208
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  • 39
    Digitale Medien
    Digitale Medien
    Morphogenesis and ductal development of the prostatic complex of the guinea pig (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 219-227 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The morphogenesis of glandular architecture of the three lobes of prostate gland of the guinea pig, lateral, dorsal, and coagulating gland was studied from 35 days gestation to 90 postnatal days. Epithelial ductal tubules of various lobes of the gland were microdissected after treatment by collagenase and displayed two dimensionally. The number of ductal tips was counted, and the volume of the ductal network was quantified using a graphic tablet. The results show that the growth and ductal morphogenesis fall into two phases: prenatal and postnatal. The first outgrowth of prostatic buds begins at 35 days gestation (gestational length is 65 days). Ductal growth and branching continues over the next 15-20 days and by 55 days gestation, approximately 60%, 79%, and 71% of the adult number of ductal tips of the lateral and dorsal lobes and coagulating gland respectively, are formed. The figures increase to 89%, 84%, and 106%, respectively, by birth. There is little increase in number of ductal tips thereafter. Postnatal growth is accomplished mainly by elongation of existing ductal network with a little additional branching but with an increase in size (volume) of the tubules. Canalization of ductal tubules occurs prenatally in all lobes but postnatal functional cytodifferentiation takes a slightly different pace among them. Ductal morphogenesis of the guinea pig prostate gland differs significantly in time-course from that of the mouse in which ductal development occurs mainly postnatally. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170209
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  • 40
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170301
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  • 41
    Digitale Medien
    Digitale Medien
    Structure of comblike teeth of the ayu sweetfish, Plecoglossus altivelis (Teleostei: Isospondyli): I. Denticles and tooth attachment (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 229-238 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure and tooth attachment of the comblike teeth and denticles of the ayu sweetfish, Plecoglossus altivelis, were examined by light and scanning electron microscopy. The denticle is composed of a spoonlike crown with a spine pointed anteriorly, a triangular plate in the cervical region, and a root that curves laterally and tapers off to a point. The root apex is fused with a long thin pedicle that turns abruptly anteriad toward the jaw bone. Planes of the spine, the spoonlike crown, the triangle plate and the root of the denticle are varied, and the denticle is twisted in the region of the triangle plane.The superficial layer of the dentine is homogeneously calcified and is considered to be enameloid, because some of the inner dentinal epithelial cells in the tooth germ are columnar and possess cellular processes at their apical ends. The dentine is fibrous and fine dentinal tubules are visible in dentine treated with sodium hydroxide and observed by scanning electron microscopy. The upper half of the root is surrounded by a dense layer of collagen fibers running parallel to the tooth axis, and the lower half is encompassed by interlaced collagen fibers. The lower part of the root is open on its lingual side. The pedicle is a long rod which is homogeneously calcified and enmeshed by interlaced collagen fibers, and it curves mediad as it nears the jaw bone. The pedicles are interposed between a layer of gelatinous connective tissue and the jaw bone and terminate on the periosteum. Comparative aspects of ayu tooth morphology are discussed. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170210
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  • 42
    Digitale Medien
    Digitale Medien
    Effects of juvenile hormone analogues upon soldier differentiation in the termite Reticulitermes santonensis (Rhinotermitidae, Heterotermitinae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 239-261 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Under the influence of juvenile hormone analogues (JHAs), termite workers are induced to differentiate into soldiers. In Reticulitermes santonensis, such induced differentiation is often incomplete, resulting in intercaste production. The morphology of the structures most affected during differentiation was analyzed descriptively and biometrically in normal workers, presoldiers, and soldiers, and in experimental intercastes. We observed that intercastes form a morphological and biometrical continuum between workers and presoldiers (presoldier intercastes), and between presoldiers and soldiers (soldier intercastes). We also compared the biochemistry of the normal individuals and of the intercastes; in contrast to workers, the intercastes possess a frontal gland secretion which differs from those of the presoldiers and soldiers. Besides intercaste characterization, we consider the mode of action of JHAs in termite differentiation. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 41 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170211
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  • 43
    Digitale Medien
    Digitale Medien
    Microtopography of Nippostrongylus brasiliensis (Nematoda: Heligmosomatidae): Free-living larval stages (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 263-271 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Microtopographic features of the various growth stages of the three free-living larval stages of the rat hookworm Nippostrongylus brasiliensis (Nematoda) were surveyed by scanning electron microscopy. These worms have a rounded anterior end and an elongated tail. Cuticular annulations were observed along the body, which also bore two ribbon-like lateral alae. Two rings of six lip-like lappets were observed around the triradiate oral opening in all larval stages. The cephalic space contained two lateral amphidial pits. The excretory pore in the third anterior part was observed in a ventral view of the larvae. No deirids were observed. The anus with a crescent-shape opening was located posteriorly. Phasmidial apertures, only observed in the third-stage larvae, opened on the lateral alae in the tail region. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 28 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170302
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  • 44
    Digitale Medien
    Digitale Medien
    Two different patterns of interrupted spermatogenesis in winter diapause and summer quiescence in the desert beetle, Omorgus freyi (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 347-358 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Spermatogenesis discontinues during both adult reproductive diapause and quiescence in the flightless males of Omorgus freyi. During both types of dormancy, spermatogenesis discontinuity is a dynamic process involving an uninterrupted supply of primary spermatocytes that undergoes partial development and lyses before spermatozoa can be formed. Notwithstanding this common feature, the pattern of discontinuity differs between the two kinds of dormancy. During reproductive diapause, spermatozoa and late spermatids are the first cells that lyse; after diapause break, spermatozoa are produced anew. During quiescence, in contrast, the first indication of discontinuity is the degeneration of late primary spermatocytes; spermatozoa apparently remain intact for a while but eventually degenerate as well. Therefore, males returning to sexual activity after a short period of quiescence may still have spermatozoa capable of fertilization. However, following a long period of quiescence, spermatozoa will be absent and must be produced anew, as in postdiapausing males. The existence of two different patterns of spermatogenesis discontinuity may indicate that each is controlled differently by the endocrine system, in response to the different environmental conditions inducing quiescence or diapause. Dual control of discontinuity may contribute to the high reproductive potential of these flightless beetles, under unpredictable and extreme desert conditions. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180309
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  • 45
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150101
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  • 46
    Digitale Medien
    Digitale Medien
    Structure of recent and fossil mysid statoliths (Crustacea, Mysidacea) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 31-49 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Statoliths of 61 Recent species representing all subfamilies of Mysidae were studied with special emphasis on internal structure. In addition 5 samples of fossil statoliths from Miocene deposits were examined. Species of Boreomysinae and Rhopalophthalminae show simple roughly spherical organic statoliths, with setae originating from the sensory cushion and anchored in the statolith with distal branches extending shortly below the surface. All other subfamilies possess mineralized statoliths of greater structural complexity, with differentiation in core and mantle, where each part may consist of up to three layers. Habitus is hemispherical to discoidal. External gross structures are dorsal tegmen, ventral fundus, and the ambitus forming the outer toroidal to semi-toroidal circumference. Setae penetrate the mantle through mineralic canals and insert on the surface of the core. As suggested by congeneric species of Schistomysis, there is no principal structural difference between statoliths mineralized with fluorite compared to vaterite. However, vaterite statoliths tend to be more often of moruloid appearance and are exceptional by showing a central conical hole (the hilum) or a central cavity in certain forms. These structures are typical of fossil calcite statoliths. In vaterite and fluorite statoliths, the mantle shows radially arranged (= spherulitic) crystal aggregates. Such arrangements are badly preserved in fossil calcite statoliths. In large extant statoliths, concentric structures, mainly in the form of superficial striation and/or concentric microstrata, are visible in coexistence with radial aggregates. Stratification is possibly due to stratified deposition of the nonmineralized gland product, while the spherulitic structure is indicative of subsequent radial growth of crystal aggregates. The structure of accessory fluorite statoliths in the statocyst of Mesopodopsis slabberi leads to the hypothesis that mantle material is formed by secretions of the caudal statocyst gland. After demineralization of fluorite, vaterite and calcite statoliths, an organic template remains showing most essential morphological features of the statolith. From this we conclude that the structure of the statolith is (almost) entirely matrix mediated. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150103
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  • 47
    Digitale Medien
    Digitale Medien
    An ultrastructural study of the dorsal lingual epithelium of the crab-eating frog, Rana cancrivora (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 89-100 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The amphibian tongue contains two types of papilla which are believed to function in gustation and in the secretion of salivary fluid. Scanning electron microscopy reveals that columnar, filiform papillae are compactly distributed over nearly the entire dorsal surface of the tongue of the frog, Rana cancrivora, and fungiform papillae are scattered among the filiform papillae. Microridges and microvilli are distributed on the epithelial cell surface of the extensive area of the filiform papillae. Light microscopy shows that the apex of each filiform papilla is composed of stratified columnar and/or cuboidal epithelium and its base is composed of simple columnar epithelium. Transmission electron microscopy reveals that most of the epithelium of the filiform papillae is composed of cells that contain numerous round electron-dense granules 1-3 μm in diameter. Cellular interdigitation is well developed between adjacent cells. On the free-surface of epithelial cells, microridges or microvilli are frequently seen. Between these granular cells, a small number of ciliated cells, mitochondria-rich cells and electron-lucent cells are inserted. In some cases, electron-dense granules are present in the ciliated cells. At higher magnification, the electron-dense granules appear to be covered with patterns of spots and tubules. Overall, the morphology and ultrastructure of the lingual epithelium of the three species of Rana that have been studied are quite similar, but they can be easily distinguished from those of Bufo japonicus. Therefore, it appears that lingual morphology is phylogenetically constrained among members of the predominantly freshwater genus Rana to produce uniformity of papillary structure and this morphology persists in Rana cancrivora despite the distinct saline environment in which it lives. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150106
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  • 48
    Digitale Medien
    Digitale Medien
    Pigment pattern formation in the larval salamander Ambystoma maculatum (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 151-163 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: As part of an ongoing comparative study of pigment patterns and their formation in embryos and larvae of ambystomatid salamanders, Ambystoma maculatum from two differnt populations, one in the northern (New York) and one in the central (Tennessee) United States, were investigated. Scanning electron microscopy was used to study early neural crest development. Light microscopy in combination with markers for the two pigment cell types (xanthophores and melanophores) made it possible to follow pigment cell migration before the pigment cells were fully differentiated. A bilateral pigment pattern consisting of two horizontal melanophore stripes surrounding an interstripe area populated by xanthophores formed in the larvae. In both populations, some variation was present in the form of a continuum ranging from clear horizontal stripes to extreme cases with a random pattern. Unlike the other ambystomatids that have been investigated, the neural crest cells in A. maculatum do not form aggregates and no vertical bars are formed. Instead, both the pattern and its formation are very similar to what has been reported for salamandrids. If pattern formation mechanisms can act as developmental constraints we would expect the A. maculatum pattern to be the primitive condition in the Ambystomatidae, using the Salamandridae as the outgroup. There is no strong support for this when aggregate formation is used as a character and mapped onto phylogenies for the group. The aggregate formation mechanism, and the pigment pattern that it leads to, have most likely been secondarily lost in A. maculatum. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150204
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  • 49
    Digitale Medien
    Digitale Medien
    A morphologic study of the ductus of the epididymis of Sus domesticus (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 183-193 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 39 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150206
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  • 50
    Digitale Medien
    Digitale Medien
    Testicular and androgen dependence of skin gland morphology in the anurans, Xenopus laevis and Rana pipiens (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 195-200 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In anuran amphibians, there is increasing evidence that exocrine glands dispersed throughout the general integument are secondary sex characters (SSC). Following the recent discovery of sexually dimorphic “breeding glands” in the dorsum of male Rana pipiens, we studied the effects of castration and testosterone treatment on the dorsal skin glands of male Xenopus laevis and R. pipiens to determine whether the dorsal breeding glands, or any other dorsal skin glands, are androgen dependent. The dorsal skin glands of X. laevis were unaffected by androgen status. By contrast, in R. pipiens, breeding, mucous, and seromucous glands responded to testosterone stimulation. Mucous glands were significantly (P 〈 0.05) larger in testosterone-treated frogs than in castrates. There was a large, but statistically insignificant, increase in the size of the dorsal breeding glands. Testosterone treatment also increased the epithelial cell height of breeding and seromucous glands (P 〈 0.05). In the skins of castrated and testosterone-treated frogs, there was a reciprocal relationship between the abundance of seromucous and breeding glands: in castrates, seromucous glands were abundant and breeding glands virtually absent, whereas in testosterone-treated frogs, breeding glands were abundant and seromucous glands less common. The total number of the two gland types was similar in both treatment groups. Glands that appeared to be intermediate in form between seromucous and breeding glands were observed in some frogs. These data suggest that seromucous glands may be the regressed form of breeding glands in the dorsal skin of R. pipiens and that the dorsal skin of R. pipiens is a SSC. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150207
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  • 51
    Digitale Medien
    Digitale Medien
    Development and fine structure of the bony scutes in Corydoras arcuatus (Siluriformes, callichthyidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 225-244 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The development and the structure of the bony scutes have been studied in a growth series of the armored catfish Corydoras arcuatus using light and electron microscopy. Fibroblast-like cell condensations appear in the dermis, in the posterior region of the caudal peduncle, and these will constitute the scute papillae. Collagen bundles of the preexisting dermis colonized by the papilla cells are remodeled and incorporated in the papilla to form, in addition to newly synthesized woven-fibered bony material, the initium of the scute. This process of formation differs from that described for the dermal papilla of an elasmoid scale. During growth, the osteoblasts surrounding the scute constitute the scute sac in which the scute grows. Parallel-fibered bone is deposited on both sides of the initium, and osteoblasts are incorporated within the scute matrix. The remodeling and incorporation of collagen bundles of the preexisting dermis is maintained during growth only in the deep, anterior region of the scute. The posterior region and the upper surface of the scute are close to the epidermal-dermal boundary. When growth slows down in the upper part of the scute, a characteristic, well-mineralized tissue, composed of thin vertical fibrils and granules and devoid of typical striated collagen fibrils, is deposited on the scute surface. A new term, hyaloine, is introduced for this nonosseous, highly mineralized layer constituting the upper part of the scute. Hyaloine shows thin electron-dense lines, which probably correspond to periodic growth arrests. The structure and localization of the hyaloine are compared to other well-mineralized, similar tissues found on the surface of the dermal skeleton in lower vertebrates. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 35 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150305
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  • 52
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160101
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  • 53
    Digitale Medien
    Digitale Medien
    Ultrastructural variations in the spermiogenesis of Triatoma infestans induced by temperature changes (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 17-27 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The reproductive process in insects may be affected by several factors, among which environmental temperature is one of the most important because of the poikilothermic condition of insects. To determine the effect of suboptimal temperature on the spermiogenic process of Triatoma infestans, males were exposed to 12°C for 10 days. In order to determine the reversibility of such alterations, males were returned to 28°C for 10 days after exposure to 12°C. Low temperature caused abnormal changes in the spermiogenic cells such as lack of spermatid orientation, general cyst disorganization, and asynchrony in the development of contiguous cysts. Highly vacuolized areas and pseudomyelinic bodies enclosing isolated or clustered vesicles of different electrodensity were also observed. At the end of the recovery time, cysts with spermatids developed synchronously. However, some presented isolated and clustered vesicles of different size and electrodensity. Some supernumerary organelles were also observed. These abnormal structures were related to processes of autophagy and phagocytosis of degenerating sexual cells. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160104
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  • 54
    Digitale Medien
    Digitale Medien
    Regionalization of eccrine and spermiophagic activity in spermathecae of the salamander Eurycea cirrigera (Amphibia: Plethodontidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 161-170 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The spermathecae of female Eurycea cirrigera are compound alveolar glands; narrow neck tubules connect the distal bulbs to a common tube that opens onto the roof of the cloaca. The common tube and neck tubules produce apical secretory vacuoles that contain a periodic acid-Schiff (PAS)+ substance for merocrine export into the lumen. This substance is produced throughout the year, although secretory vacuoles are less numerous during the period of reproductive inactivity in the summer. When sperm are present, the product from the secretory vacuoles bathes sperm in the lumen. Sperm are in orderly arrays and never are embedded in the cytoplasm of the common tube or neck tubules. The distal bulbs do not produce PAS+ secretory vacuoles, and are actively spermiophagic as long as sperm are present. Sperm become embedded in the epithelium of the distal bulbs where lysosomes degrade sperm. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170205
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  • 55
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180301
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  • 56
    Digitale Medien
    Digitale Medien
    Ultrastructural study of the ovary of the sessile scyphozoan, Haliclystus octoradiatus (Cnidaria: Stauromedusae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 225-236 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: An ultrastructural study of the ovary of the sessible jellyfish, Haliclystus octoradiatus, indicates that it is fundamentally different from that of other scyphozoans and is the most structurally complex within the class. Oocytes develop within a series of spherical, sac-like ovarian follicles consisting of an enlarged intercellular space between two layers of subumbrellar gastrodermis. Developing oocytes are largely restricted to a thin germinal epithelium at the periphery of each follicle and gradually migrate toward the lumen as they mature. Individual oocytes are surrounded by early germ cells and follicle-like accessory cells of presumed somatic origin. Similar folliclelike cells have not been described in the Cnidaria previously. Vitellogenesis appears to involve the combined activity of the Golgi complex and associated rough endoplasmic reticulum. Ovarian morphology may be helpful in deciphering phylogeneitc relationships within the Cnidaria. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180210
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  • 57
    Digitale Medien
    Digitale Medien
    Rostrate pedicellariae: A morphologically distinct form of echinoid test appendage (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 237-247 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The term rostrate was introduced by Mortensen ('07) to describe a type of pedicellaria he found in spatangoids. These pedicellariae resemble tridentate ones but have arching valves. Unlike the main categories of echinoid pedicellariae, no clear diagnosis of the rostrate form exists. This work examines the detailed morphology of the valves of rostrate pedicellariae observed by light and scanning electron microscopy and compares the shapes and dimensions of their component parts with tridentate pedicellariae. The data reveal considerable differences between the two, which warrant the recognition of rostrate pedicellariae as a distinct form. A diagnosis is given. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180302
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  • 58
    Digitale Medien
    Digitale Medien
    Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 257-280 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson) is a small carcharhinid that is a common year-round resident along the southeast coast of the United States. It is viviparous and its embryos develop an epithelio-vitelline placenta. Females enter shallow water to give birth in late May and early June. Mating occurs shortly after parturition, and four to seven eggs are ovulated. Fertilized eggs attain the blastoderm stage in early June to early July. Separate compartments for each egg are formed in the uterus when the embryos reach 3-30 mm. Embryos depend on yolk for the first 8 weeks of development. When embryos reach 72 mm their yolk supply is nearly depleted and they shift to matrotrophic nutrition. When the embryos reach 40-55 mm, placental development begins with the vascularization of the yolk sac where it contacts the uterine wall. Implantation occurs at an age of 8-10 weeks by which time the embryos reach 70-85 mm. The expanding yolk sac engulfs the maternal placental villi, and its surface interdigitates with the villi to form the placenta. The rest of the lumenal surface of the uterus is covered by non-placental villi that appear shortly after implantation. Histotrophe production by the non-placental villi begins just after their formation. The placenta grows continuously during gestation. The egg envelope is present throughout gestation, separating maternal and fetal tissues. Embryos develop numerous appendiculae on the umbilical cord. Young sharks are born at 290-320 mm after a gestation period of 11 to 12 months. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180304
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  • 59
    Digitale Medien
    Digitale Medien
    The male reproductive system and mechanism of sperm transfer in Argulus japonicus (Crustacea: Branchiura) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 51-63 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The histomorphology of the male reproductive system and surface morphology of the “peg-and-socket” in Argulus japonicus are described from serial sagittal and transverse sections and scanning electron micrographs. The prostate complex consists of a glandular part, a reservoir for storing the secretion, and an efferent duct opening into the ejaculatory duct. The openings of both the vas deferens and the prostate duct into the ejaculatory duct are guarded by sphincters. The ejaculatory ducts, which are lined by tall columnar epithelial cells, do not open into the cuticle-lined genital atrium but are blind-ending tubes. This observation and results obtained from observing live specimens, as well as the fact that no spermatophores are formed, suggest that semen could leave the ejaculatory duct only after puncturing of its walls. It is suggested that sperm transfer is accomplished in the following manner: during copulation contraction of the muscular walls of the vas deferens and prostate duct causes semen to be pumped into the ejaculatory duct, which is then closed off by sphincters and a high internal pressure is developed. When a spermathecal spine penetrates the walls of the ejaculatory duct, semen flows from the ejaculatory duct into the spermathecal vesicle due to the higher pressure in the ejaculatory duct. This mechanism is analogous to the sucking up of fluid with a hypodermic syringe. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150104
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  • 60
    Digitale Medien
    Digitale Medien
    Anatomy of the larva of Amathia vidovici (Bryozoa: Ctenostomata) and phylogenetic significance of the vesiculariform larva (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 1-29 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Amathia vidovici (Vesiculariidae) has a lecithotrophic coronate larva. The apical disc of A. vidovici larvae is more complex than that of other vesiculariids and includes a new cell type, which may be glial-like in function. A massive nerve nodule consists only of neural processes; as no ganglia or other evidence of interneurons were found, sensory cells apparently innervate their effectors directly. Putative synaptic junctions within the nerve nodule indicate that both receptor and effector cells send processes to this neuropile. Some 44 intercoronal cells of three types, two of which are new, are interspersed among the approximately 40 coronal cells. Juxtapapillary bodies, a unique sensory complex previously known only from Bowerbankia gracilis larvae, also occur in A. vidovici. A large refractile body, which is of uncertain function and is positioned near the center of the larva, is described for the first time.A comparison of vesiculariid larvae that have been studied at the ultrastructural level reveals that larvae of Amathia vidovici and Bowerbankia gracilis are more similar to each other than either is to B. imbricata. Differences between the two Bowerbankia species, however, may reflect relative detail of their study and differences in interpretation rather than intergenic plasticity. Nevertheless. a distinctive suite of larval characteristics are shared by other members of the family Vesiculariidae, justifying a specific name - vesiculariform - for their larvae. A number of the defining characteristics of vesiculariform larvae also appear in the carnosan superfamily Victorelloidae. This finding is consistent with arguments based on adult characteristics that the Victorelloidea are ancestral to the Vesicularioidea. If this geneology is correct, one can predict that those vesiculariform traits which originated in the victorellids are plesiomorphic not only to the Family Vesiculariidae but to all sister taxa placed in the Vesicularioidea. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150102
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  • 61
    Digitale Medien
    Digitale Medien
    Cranial osteogenesis in Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 119-149 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The pattern of onset and general rate of cranial ossification are compared in two marsupials, Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae). In both species a similar suite of bones is present at birth, specifically those surrounding the oral cavity and the exoccipital, and in both postnatal events follow a similar course. The facial skeleton matures more rapidly than the neurocranium, which is characterized by an extended period of ossification. Most dermal bones begin ossification before most endochondral bones. Endochondral bones of the neurocranium are particularly extended in both the period of onset of ossification and the rate of ossification. These data confirm suggestions that morphology at birth is conservative in marsupials and we hypothesize that the pattern of cranial osteogenesis is related to two distinct demands. Bones that are accelerated in marsupials are correlated with a number of functional adaptations including head movements during migration, attachment to the teat, and suckling. However, the very slow osteogenesis of the neurocranium is probably correlated with the very extended period of neurogenesis. Marsupials appear to be derived relative to both monotreme and placental mammals in the precocious ossification of the bones surrounding the oral cavity, but share with monotremes an extended period of neurocranial osteogenesis. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150203
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  • 62
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150301
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  • 63
    Digitale Medien
    Digitale Medien
    Falciparum malaria in naturally infected human patients: I. Ultrastructural differences between malaria pigments in intraerythrocytic asexual and sexual forms (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 201-206 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Venous blood samples were taken from patients naturally infected with the human malaria parasite Plasmodium falciparum. Two types of malaria pigment (MP) particles have been demonstrated in intraerythrocytic asexual forms (trophozoites and schizonts), while a single type was detected in gametocytes. Type I MP particles, found in both asexual and sexual forms, are electron-dense. It is suggested that these are proteinaceous and may be intermediate, utilizable metabolic products that serve as a food reserve during development of the parasite in the human host and also during the growth cycle of the sexual form in the mosquito. In asexual forms, type I particles occur within food vacuoles (FV) containing semidigested hemoglobin (Hg), while they are unenveloped in the cytoplasm of the sexual forms. Type II MP particles, found in electron-lucent residual bodies, are crystalloid and of low electron density. It is suggested that these are the final, waste product of Hg digestion in the asexual forms. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150302
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  • 64
    Digitale Medien
    Digitale Medien
    Falciparum malaria in naturally infected human patients: II. Ultrastructural alterations to erythrocytes infected with asexual forms (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 207-212 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Ultrastructural alterations of human erythrocytes infected with asexual forms of Plasmodium falciparum were studied in naturally infected Saudi patients. These included surface knobs and nodules as well as invaginations associated with cytopasmic vesicles observed in erythrocytes infected with asexual forms of the parasites. Such nodules and surface invaginations have been previously described only in erythrocytes infected with P. ovale and P. vivax, respectively. Within the cytoplasm of infected erythrocytes were membrane-bound clefts, similar to those that appear to be a common characteristic in all red cells infected with malaria parasites. Vacuolations were often seen in the peripheral cytoplasm and may represent hemolyzed areas. Collapsed cells with an internal-lucent interior and surrounded by an irregularly folded membrane may represent completely hemolyzed erythrocytes. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150303
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  • 65
    Digitale Medien
    Digitale Medien
    A microscopic investigation of the lymphoid organs of the beluga, Delphinapterus leucas (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 261-287 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Lymphoid organs from belugas, Delphinapterus leucas, ranging in age from less than one to 16 years, were harvested during a sanctioned hunt to investigate morphology. The spleen is divisible into red and white pulp and a stroma consisting of a reticular network, a collagenous capsule, and trabeculae containing smooth muscle bundles. White pulp areas appear to be devoid of follicles and consist mainly of periarteriolar lymphatic sheaths (PALS), that are larger in younger than in older belugas. Definitive marginal zones between red and white pulp are difficult to discern in older belugas. Lymph nodes are similar to those of other mammals; they possess a follicular cortex surrounding a vascular medulla composed of lymphatic cords and sinuses. Smooth muscle is abundant in the medullary region, usually in close proximity to sinuses. The expansive nodular mass at the root of the mesentery, often referred to as the “pseudopancreas,” is similar to lymph nodes in microscopic architecture. Pharyngeal tonsils and gut-associated lymphoid tissue (GALT) are found along the digestive tract and display an “active” morphology. Tonsils are comprised of lobules of follicles separated by vascular connective tissue. Epithelial-lined crypts communicate with the pharyngeal lumen. GALT consists of diffuse and follicular lymphocytes within the intestinal mucosa and submucosa. The thymus is well developed in the younger belugas, with lobules divisible into densely packed cortical zones of thymocytes and more loosely arranged medullary lymphocytes. Hassall's corpuscles are occasionally visible within the medulla. Cetaceans diverged evolutionarily from other mammals over 55 million years ago. This study investigates changes in lymphoid organ morphology in a species that now inhabits a unique ecological niche. This study also lays the groundwork for functional investigation of the beluga immune system, particularly as it relates to differences between healthy and stranded animals. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150307
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  • 66
    Digitale Medien
    Digitale Medien
    Gliding flight in the American Kestrel (Falco sparverius): An electromyographic study (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 213-224 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Electromyographic (EMG) activity was studied in American Kestrels (Falco sparverius) gliding in a windtunnel tilted to 8 degrees below the horizontal. Muscle activity was observed in Mm. biceps brachii, triceps humeralis, supracoracoideus, and pectoralis, and was absent in M. deltoideus major and M. thoracobrachialis (region of M. pectoralis). These active muscles are believed to function in holding the wing protracted and extended during gliding flight. Quantification of the EMG signals showed a lower level of activity during gliding than during flapping flight, supporting the idea that gliding is a metabolically less expensive form of locomotion than flapping flight. Comparison with the pectoralis musculature of specialized gliding and soaring birds suggests that the deep layer of the pectoralis is indeed used during gliding flight and that the slow tonic fibers found in soaring birds such as vultures represents a specialization for endurant gliding. It is hypothesized that these slow fibers should be present in the wing muscles that these birds use for wing protraction and extension, in addition to the deep layer of the pectoralis. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150304
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  • 67
    Digitale Medien
    Digitale Medien
    Evolution and functional significance of tendon ossification in woodcreepers (Aves: Passeriformes: Dendrocolaptinae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 289-300 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The woodcreepers, a clade of scansorial, neotropical birds, are distinctive among passerines in having extensive tendon ossification. Dissection of 42 of the 50 species indicates that such ossification in the hindlimb is limited almost entirely to tendons of insertion of the crural muscles. Most crural muscles have ossifications, and in all but one the ossified tendons are long and thin. Preliminary dissection revealed a similar pattern among ossified wing tendons. Phylogenetic analysis suggests that extensive tendon ossification is a synapomorphy of the woodcreepers. The species of Dendrocincla, which form a clade, show secondary reduction of ossification in some tendons, which may be correlated with increased intraspecific variation and with an expansion of foraging habits and postures to include nonscansorial behaviors. In contrast, the larger woodcreepers, other than Drymornis bridgesii and Nasica longirostris, form a clade with virtually no loss in ossification or evidence of intraspecific variation, even in large series of two species. Phylogenetic losses do not occur for the primary flexor of the ankle (M. tibialis cranialis), whereas two extensors (Mm. fibularis longus and gastrocnemius pars lateralis) show a complex pattern of derivation and loss. Previous biomechanical studies demonstrate that ossification increases the stiffness of tendons, making them stretch less under a given force. These structural and phylogenetic patterns are consistent with the view that hindlimb tendon ossification in woodcreepers is an adaptation to resist increased forces that act to extend the limb during vertical climbing. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052150308
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  • 68
    Digitale Medien
    Digitale Medien
    Follicular dynamics and germinal bed activity during the annual ovarian cycle of the lizard, Calotes versicolor (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 1-7 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Changes in size frequency distribution of extrastromal follicles, atretric follicles (AF), and the number of oogonia, oocytes, and primordial follicles in the ovaries are studied in Calotes versicolor during its annual reproductive cycle. Extrastromal follicles were graded into stages I to VI based on their diemeter. Stage I (0.5-0.75 mm) follicles are found throughout the year. The recruitment of stage II (0.76-1 mm) and stage III (1.10-2 mm) follicles occurs during December and March, respectively. Follicles of stage I-III are found in greater number in May. Stage IV vitellogenic follicles (2.10-3 mm) are recruited in April. Advanced vitellogenic follicles (stage VI) are formed between May and August. From April to August, the ovaries of lizards contain vitellogenic follicles of stages IV or V or VI suggesting that once a set of follicles enters vitellogenic phase there is no recruitment of another set of vitellogenic follicles from previtellogenic follicles until the former ovulates. The presence of vitellogenic follicles and at least two sets of CL in July-August suggest that C. versicolor may oviposit at least three clutches of eggs per season. The clutch size in this lizard varies from a maximum 24 eggs in May to a minimum of 13 eggs in September. The previtellogenic AF are found throughout the year. Atresia is more prevalent in stage III suggesting that these follicles are more prone to become atretic. Interestingly, atresia of vitellogenic follicles occurs rarely. Each ovary in C. versicolor has two germinal beds. The germinal beds contain a greater number of oogonia (536-696), primary oocytes (40-71), and primordial follicles (32-55) during prebreeding and early breeding phases of the ovarian cycle. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160102
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  • 69
    Digitale Medien
    Digitale Medien
    Ultrastructure of the spermatozoon of the teleost fish Acanthopagrus schlegeli (Perciformes: Sparidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 29-33 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Ultrastructurally the spermatozoon of Acanthopagrus schlegeli (Sparidae) has a spherical, homogeneously electron-dense nucleus with a deep axial nuclear fossa, and an unusual notch, shaped like a bowtie, in the nuclear region. The short midpiece contains four spherical mitochondria and encircles the basal body of the flagellum. It is concluded that the spermatozoon is of a primitive type, although it is characterized by several unique features which may provide useful systematic characters. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160105
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  • 70
    Digitale Medien
    Digitale Medien
    In-series fiber architecture in long human muscles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 35-45 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The fiber architecture of adult human sartorius and gracilis muscles was examined using a combination of fiber microdissections and histological methods. Intact fibers were dissected from fascicles of muscle strips that were digested in nitric acid. All of these fibers terminate intrafascicularly by tapering to a fine strand at one or both ends. They measure 4-20 cm after correction for shrinkage. Systematic dissections of 1 cm long blocks sampled at intervals along the muscle length suggest that tapered fiber endings occur at all locations along the muscle but are most common centrally; here they accounted for up to 14% of dissected fibers in each block. Transverse sections of muscle confirm that fiber profiles with small diameters occur at all levels of the muscle but are especially common in sections more than 5 cm from its origin or insertion. The architectural arrangement demonstrated here suggests that long human muscles, like muscles in other species, are composed of relatively short, in-series fibers. This has many implications for the neural activation and force-developing behavior of these muscles that must be considered when paralyzed muscles are reanimated using electrical stimulation. Further, it may predispose long muscles to certain types of neuromuscular damage and dysfunction. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160106
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  • 71
    Digitale Medien
    Digitale Medien
    Suboccipital muscles in the cat neck: Morphometry and histochemistry of the rectus capitis muscle complex (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 47-63 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The morphometry, histochemistry, and biomechanical relationships of rectus capitis muscles were examined in adult cats. This family of muscles contained six members on the dorsal, ventral, and lateral aspects of the upper cervical vertebral column. Three dorsal muscles (rectus capitis posterior major, medius, and minor) formed a layered complex spanning from C1 and C2 to the skull. Rectus capitis posterior major was composed predominantly of fast fibers, but the other two deeper muscles contained progressively higher proportions of slow fibers. One ventral muscle, rectus capitis anterior major, was architecturally complex. It originated from several cervical vertebrae and appeared to be divided into two different heads. In contrast, rectus capitis anterior minor and rectus capitis lateralis were short, parallel-fibered muscles spanning between the skull and C1. The ventral muscles all had nonuniform distributions of muscle-fiber types in which fast fibers predominated. Dorsal and ventral muscle groupings usually had cross-sectional areas of 0.5 cm2 or more, reflecting a potential capacity to generate maximal tetanic force in excess of 9 N. Biomechanical analyses suggested that one muscle, rectus capitis lateralis, had its largest moment in lateral flexion, whereas the other muscles had large, posturally dependent moment arms appropriate for actions in flexion-extension. The observation that most rectus muscles have relatively large cross-sectional areas and high fast-fiber proportions suggests that the muscles may have important phasic as well as postural roles during head movement. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160107
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  • 72
    Digitale Medien
    Digitale Medien
    Organization of hematopoietic tissue in the intermolt lobster, Homarus americanus (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 65-78 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Hematopoiesis in the American lobster Homarus americanus, as in most decapod crustaceans, occurs in a thin tissue covering the dorsal surface of the foregut. This tissue is composed of loosely attached, ovoid lobules containing the hematopoietic precursors and maturing hemocytes. Release of hemocytes into the dorsal hemocoel is accomplished by rupture of a portion of the connective tissue capsule covering the lobule. Cross sections of the lobules contain between 6 and 40 hematopoietic cells, of which approximately 90% constitute stages in granulocyte maturation and 10% are intermediates in hyaline cell maturation. Hematopoietic precursors in these two lines are similar to those recently described in a penaeid shrimp Sicyonia ingentis. The mitotic rate averaged 5.1% (range = 0.7% to 15.8%) in intermolt lobsters, 90% comprised granulocyte precursors. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160108
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  • 73
    Digitale Medien
    Digitale Medien
    Structural characteristics of marsupial brood pouches of the antarctic sea urchins Abatus nimrodi and Abatus shackletoni (Echinoidea: Spatangoida) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 79-93 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Marsupial spines, tubercles, and pedicellariae of the antarctic brooding spatangoids Abatus nimrodi and Abatus shackletoni have been examined by scanning electron microscopy. Individual brood pouches of A. nimrodi may hold up to 28 embryos and juveniles and those of A. shackletoni may hold up to 38 lecithotrophic embryos and juveniles. Juveniles can be divided into (a) those with early development of external elements and a mean size of 2.0 and 1.6 mm, respectively, and (b) those equipped with fully developed external elements and a mean length of 4.3 and 2.8 mm, respectively. Mean diameters of aboral brood pouch openings of A. nimrodi and A. shackletoni were 6.5 and 4.1 mm, respectively. Brood pouches contain tall, distally enlarged spines, and smaller, layered cover-spines, which form a protective arch over the marsupia. There are also slender brood-pouch-bottom spines, which have an extremely thickened spinal epidermis. A. nimrodi has mainly bidentate, but also triand quadrodentate pedicellariae. A. shackletoni has two forms of tridentate, rostrate, and globiferous pedicellariae. In A. shackletoni, marsupial spine density is significantly lower than in A. nimrodi. These differences may be related to distinct sediment characteristics in their respective habitats. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160109
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  • 74
    Digitale Medien
    Digitale Medien
    Announcement (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 113-113 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160111
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  • 75
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160201
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  • 76
    Digitale Medien
    Digitale Medien
    Ultrastructure of prothoracic glands during larval-pupal development of the tobacco hornworm, Manduca sexta: A reappraisal (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 95-112 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure of Manduca sexta prothoracic glands was investigated using a protocol that preserves membranes. During the last larval stadium, prothoracic gland cells increase in diameter, volume, protein content, and perhaps number, enhancing their capacity to produce ecdysteroids. The glands' strand-of-cells morphology, their in situ location, the presence of gap junctions between cells, and junctional foot-like structures within cells support previous findings that prothoracicotropic hormone stimulates ecdysteroidogenesis via Ca2+-induced Ca2+ release. A different method of tissue fixation from that previously used to investigate the ultrastructure of Manduca sexta prothoracic glands has revealed a significantly different ultrastructure. These new findings begin to define roles for endoplasmic reticulum and mitochondria in ecdysteroid synthesis and support the hypothesis that the glands secrete the steroid hormone via exocytosis. The structural dynamics of the glands are discussed in the context of the glands' function during Manduca sexta larvalpupal development. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160110
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  • 77
    Digitale Medien
    Digitale Medien
    Structure and histochemical organization of the spleen of Agama stellio (Sauria: Agamidae) and Chalcides ocellatus (Sauria: Scincidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 115-120 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The spleen of Agama stellio is composed mainly of red pulp; the white pulp is poorly developed, and its clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and pigment cells. The spleen of Chalcides ocellatus is encapsulated by connective tissue and is composed of white and red pulp. The white pulp consists of lymphoid tissue that surrounds the central arterioles, forming the periarteriolar lymphocyte sheath (PALS). The red pulp is composed of a system of venous sinuses and cords. The results of various histochemical procedures designed to demonstrate mucosubstances, proteins, and nucleic acids indicate that the spleen in these species resembles the mammalian spleen. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160202
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  • 78
    Digitale Medien
    Digitale Medien
    Cleavage pattern in embryos of Haliotis tuberculata (Archaeogastropoda) and gastropod phylogeny (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 121-139 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The early cleavage pattern in embryos of the archaeogastropod Haliotis tuberculata strongly resembles the cleavage pattern of the archaeogastropods Trochus and Patella. It typically deviates from the cleavage patterns found in embryos of more advanced Archaeogastropoda, Caenogastropoda (the majority of the meso- and neogastropods), and Euthyneura (opisthobranch and pulmonate gastropods). It is assumed that the cleavage pattern found in Haliotis, Trochus, and Patella represents the ancestral pattern. A regular pattern of heterochronic changes in the succession of the formation of the larval trochoblasts and the stem cell of the adult mesoderm can be observed from the more primitive Archaeogastropoda to the more advanced Euthyneura. This observation strengthens the idea that the early cleavage pattern contains significant phyletic information. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 33 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160203
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  • 79
    Digitale Medien
    Digitale Medien
    On the structure of the aortic valves in snakes (Reptilia: Serpentes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 141-159 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Aortic valve morphology was examined in 32 species of snakes representing 28 genera and 11 families and a diversity of habitat preferences. The results largely agree with previous studies but include some previously undescribed features, such as the cranial displacement of the cusps in the left aorta in some species and the structure of the opposing cusps of the interaortic foramen. Few features of the aortic valves are uniform among species. The pattern of morphological variation does not correlate with simple habitat preference (e.g., terrestrial, arboreal); however, some of the variation, particularly in the valves themselves, correlates with taxonomic relationships. We suggest that the presence of an interaortic foramen, with its associated valve, could result in an interaortic shunt of blood that potentially alters hemodynamics and flow patterns in the systemic circulation of snakes. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160204
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  • 80
    Digitale Medien
    Digitale Medien
    Microstructure, ontogeny, and evolution of scale surfaces in xenosaurid lizards (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 161-177 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Both scanning electron and light microscopy were used to examine the epidermal structure of scales taken from several ontogenetic stages of Xenosaurus grandis and Shinisaurus crocodilurus. In addition, scales from all xenosaurid species were examined by scanning electron microscopy to determine scale surface variation among genera, species, and subspecies. A varied and phylogenetically informative morphology characterizes the scale surfaces of xenosaurid lizards. Scale surface morphology is conservative among the species and subspecies of Xenosaurus, but is more variable between the two xenosaurid genera. Their scale surfaces are characterized by folds in the oberhautchen, beta, mesos, and alpha epidermal layers, forming polygonal ridges of a type previously described for the Iguania. The three species of Xenosaurus possess lenticular scale organs, whereas Shinisaurus has scale organs with spikes (bristles). The spikes of Shinisaurus are formed by the beta and oberhautchen layers, with the alpha layer forming a dome-shaped cap over a dermal papilla. Shinisaurus crocodilurus exhibits a dramatic ontogenetic change in scale surface morphology, that is here reported for the first time in any lizard. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160205
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  • 81
    Digitale Medien
    Digitale Medien
    Histology of the late-stage placentae in the matrotrophic skink Chalcides chalcides (Lacertilia; Scincidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 179-195 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Examination of late-stage placental material of the lizard Chalcides chalcides from the Hubrecht Laboratorium (Utrecht, The Netherlands) reveals several cytological and histological specializations that appear to have been superimposed over a morphological pattern that is typical for squamates. The chorioallantoic placenta is highly vascularized and consists of a single mesometrial placentome and a generalized paraplacentomal region, both of which are epitheliochorial. The placentome is deciduate, and contains deeply interdigitating folds of hypertrophied uterine and chorioallantoic tissue. Chorionic epithelium lining the placentome comprises enlarged, microvilliated cells, a small proportion of which are diplokaryocytes. The placentomal uterine epithelium is not syncytial and consists of enlarged cells bearing microvilli. The yolk sac placenta is a true omphaloplacenta (sensu stricto), being formed by juxtaposition of uterine tissues to an avascular, bilaminar omphalopleure. Epithelium of the omphalopleure is stratified and is hypertrophied into papillae that project into detritus of the uterine lumen. The omphalopleure is separated from the yolk sac proper by a yolk cleft that is not confluent with the exocoelom and is not invaded by the allantois. Neither an omphalallantoic placenta nor a true choriovitelline placenta is present in late gestation. Morphologically, the mature placentae of C. chalcides are among the most specialized to have been described in reptiles, reflecting the substantial maternal-fetal nutrient transfer that occurs in this species. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160206
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  • 82
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160301
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  • 83
    Digitale Medien
    Digitale Medien
    Chiropteran tendon locking mechanism (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 197-208 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Rather than the usual mammalian scheme in which tendon and sheath surfaces provide as little friction as possible, the tendons and sheaths of many bats have a locking segment on the manual and pedal flexor tendon complex. This tendon locking mechanism (TLM) exists opposite the proximal phalanges of each toe and pollex of many bats. Its structure, similar to a ratchet mechanism, assists bats in hanging with little muscular effort. The third digit of the pelvic limb and the pollex of species representing 15 chiropteran families were studied to determine the presence or absence, morphology, and function of the TLM. Most of the species studied have a TLM consisting of a patch of tubercles on the ventral surface of the flexor tendon associated with the proximal phalanx of each pollex or toe. The sheath adjacent to this portion of the flexor tendon has a series of transverse folds or ridges, which, when engaged with the tubercles on the tendon, lock the tendon in place. The TLM is similar in megachiropterans and microchiropterans possessing it. The TLM is absent, however, in some of the microchiropterans studied, most notably in the phyllostomids. Since many birds have a TLM similar to that of bats, it is an excellent example of the convergent evolution of a feature brought about by similar functional pressures on birds and bats. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160207
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  • 84
    Digitale Medien
    Digitale Medien
    Development of the inner ear of the brown trout (Salmo trutta fario): I. Gross morphology and sensory cell proliferation (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 209-223 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The gross development of the trout inner ear between embryonic and juvenile stages was studied by light microscopy. The otocyst has already formed in 3-4 mm embryos. The semicircular canals begin to separate from the utriculo-saccular cavity in 6 mm embryos, the anterior canal first, then the posterior and the horizontal canal later. The formation of the saccular cavity begins in 7 mm embryos, whereas that of the lagena occurs in 18 mm fry. The first macular primordia appear before the separation of cavities. The anterior and horizontal crests arise from the primordium of the utricular macula, and the posterior crest, macula lagena, and macula neglecta arise from that of the saccular macula. The macula lagena and macula neglecta appear later. The sensory areas of the labyrinth and the number of receptor cells grow continuously between the embryonic and juvenile stages. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 44 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160208
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  • 85
    Digitale Medien
    Digitale Medien
    Early events in myofibrillogenesis and innervation of skeletal, sound-generating muscle in a teleost fish (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 225-239 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The plainfin midshipman, Porichthys notatus, generates acoustic communication signals through the rapid contraction of a pair of vocal (sonic) muscles attached to the walls of the swimbladder. Light and electron microscopic methods were used to study two aspects of sonic muscle ontogeny: (1) the development and transformation of myotubes into muscle fibers and (2) innervation, including the formation of sonic neuromuscular junctions and the myelination of sonic motor axons. Sonic motor axons are associated with sonic mesenchyme during its initial migration away from occipital somites. However, myofibrillogenesis, the formation of neuromuscular junctions, and axon myelination do not occur until sonic mesenchyme reaches its final destination (i.e., the swimbladder). A continuum of developing myotubes is present rather than two temporally distinct populations of primary and secondary myotubes as observed for skeletal muscles in mammalian and avian species. Potential reasons for the lack of primary and secondary myotubes are considered, including the functional homogeneity of the sonic motor system and the sonic muscle's unique architecture, namely its direct attachment to the wall of the swim-bladder. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160209
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  • 86
    Digitale Medien
    Digitale Medien
    Development of the inner ear of the brown trout (Salmo trutta fario): II. Cytodifferentiation and innervation of sensory cells (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 241-257 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The study of the sensory organs of the trout labyrinth by means of electron microscopy show that hair cells differentiate gradually in these organs; all of them produce new cells over a long period. The course of cytodifferentiation follows a similar pattern in all organs. Afferent nerve fibers and terminals are found at approximately the same time that sensory cells are being differentiated; the efferent synapses appear latter in development. The maturation of the both types of synapses is described. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 40 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160302
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  • 87
    Digitale Medien
    Digitale Medien
    Ultrastructure and cytochemistry of secretory cells in the skin of the leech, Dina lineata (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 295-304 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ultrastructure and histochemical features of the two types of secretory cells in leech skin are described. Pear-shaped cells secrete mucus containing carboxylated mucosubstances, while tubular cells produce a mucus containing a mixture of neutral, carboxylated, and sulfated mucosubstances. Pear-shaped secretory cells have two types of neuroglandular junctions, one containing dense-core serotonergic vesicles and the other small clear vesicles. Tubular secretory cells have large terminals, with many clear vesicles thought to be cholinergic. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160305
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  • 88
    Digitale Medien
    Digitale Medien
    Entry of nephrons into the collecting duct network of the avian kidney: A comparison of chickens and desert quail (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 259-269 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The avian kidney contains a population of nephrons with and without loops of Henle. How the collecting ducts of this heterogeneous population of nephrons merge to exit as single ducts from the medullary cones has been uncertain. The results of this study show that the collecting duct tree begins with the coalescence of the distal tubules of pairs of loopless nephrons. These primary collecting ducts receive output from only loopless nephrons. Primary collecting ducts fuse in pairs and become secondary collecting ducts. They receive the distal tubules of transition nephrons. Pairs of secondary collecting ducts fuse and become tertiary collecting ducts. Tertiary collecting ducts receive the distal tubules of looped nephrons. Thus, the fluid from all nephron types comingles as it passes through the medullary cone. The results of this study also show that the anatomical arrangement of medullary cones does not permit the output from one medullary cone to enter a second medullary cone. Thus, all the medullary cones function as parallel units. This anatomical organization of the avian kidney affects its ability to produce a urine hyperosmotic to the plasma. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160303
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  • 89
    Digitale Medien
    Digitale Medien
    Continuous and discontinuous growth in the otolith of Macruronus novaezelandiae (Merlucciidae: Teleostei) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 271-294 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Viewed by transmitted light, the lapillus and astericus otoliths Macruronus novaezelandiae (Merlucciidae) contain radial bands of similar width to the distances between steps on the surface of the otolith. The sagitta otolith has a multi-prismatic structure and shows differences in ultrastructure between its dorsal and ventral growth axes, as well as its sulcal (inward-facing) and anti-sulcal (outward-facing) parts. The ultrastructure of the sagitta shows that not all of the optical and etched checks in the central growth axis represent true discontinuities in the crystal growth of the otolith; they are the result of refraction around narrow optically active refractive bands. Microincrement growth along the dorsal prisms of the otolith from the primordium to the growing edge shows discontinuities in crystal growth at the boundary of the primordium and at the intersection of prisms. Parts of the ventral edge of the otolith show discontinuous crystal growth apparently caused by the physical growth restriction at the point at which the otolith is supported by the skull. Both the anti-sulcal and sulcal parts of the otolith often show discontinuities in the crystal structure alongside zones of continuous microincrement deposition, or evidence of continuous crystal growth, documenting simultaneous continuous and discontinuous growth in closely juxtaposed parts of the same otolith. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160304
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  • 90
    Digitale Medien
    Digitale Medien
    Androgen effects on vocal muscle structure in a teleost fish with inter- and intra-sexual dimorphism (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 305-318 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The plainfin midshipman fish Porichthys notatus has both interand intra-sexual dimorphism in the sound-producing (vocal or sonic) muscles attached to the swimbladder wall. The “Type I” and “Type II” male morphs differ in that dramatic structural changes related to sexual maturity occur in the mass, the area of mitochondria-filled sarcoplasm, and the myofiber number of the sonic muscles of Type I males, but not in those of Type II males (nor of females). Androgen implantation for 9 weeks markedly increased the relative sonic muscle size in juvenile males, juvenile females, and Type II males, whereas estradiol or cholesterol treatment did not. The principal androgen effect on myofiber structure was an increase in the area of mitochondria-filled sarcoplasm. The ratio of sarcoplasm area to myofibril area (Sr/Mf) increased by 1.4- to 2-fold in myofibers of all androgen-treated groups, with the greatest structural change occurring in juvenile males. When androgen implants were removed from juvenile males, the muscle mass and Sr/Mf ratio reverted toward the unimplanted juvenile phenotype. Total fiber number in sonic muscle increased significantly in juvenile males following androgen implantation but did not detectably change in juvenile females or Type II males. These results suggest: (1) sonic muscle in Porichthys notatus is an androgen target tissue, (2) fiber structure and fiber number are androgen-sensitive features, and (3) there exist sex- and morph-specific patterns of sonic muscle responsiveness to androgen implants. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160306
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  • 91
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of RNA in the chromatoid bodies of undifferentiated cells (neoblasts) in planarians by the RNase-gold complex technique (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 319-326 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Undifferentiated cells of planarians (Platyhelminthes, Turbellaria), also called neoblasts, are totipotent stem cells, which give rise to all differentiated cell types, while maintaining their own density by cell proliferation. Neoblasts are the only somatic cells of planarians bearing chromatoid bodies in their cytoplasm; these organelles disappear as differentiation takes place. Studies on germinal cells of several groups of organisms have shown that chromatoid bodies contain substantial amounts of RNA. To test its presence in neoblasts, we have used an RNase-gold technique. We found chromatoid bodies labeled with RNase-gold particles. Heterogeneity in the density of the label, may be correlated with the functionality and complexity of these organelles. The gold marker was also present over the nucleus and rough endoplasmic reticulum, but mitochondria, secretory granules, and the extracellular space were devoid of label. This specific localization of RNA in planarian chromatoid bodies supports earlier findings on germ cells and embryonic cells in a variety of organisms, indicating that chromatoid bodies are information-storage structures, essential during the process of cell differentiation. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160307
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  • 92
    Digitale Medien
    Digitale Medien
    Osmoregulatory-like mitochondria-rich cells in the developing pancreatic ducts of young anuran tadpoles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 339-350 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Pancreatic ducts of young posthatching Rana temporaria tadpoles are the main component of the developing pancreas. At this stage (free-swimming tadpoles with internal gills), duct cells display a high degree of development of basal and lateral outfoldings of the cell membrane with extensive interdigitation, and numerous mitochondria are present throughout the cytoplasm. Wide intercellular spaces also exist, sometimes forming canaliculi-like structures. Since these traits are characteristic of cells engaged in osmotic regulation, we suggest the possibility that this temporary duct system participates in such control. Duct cells in tadpoles with well-developed hindlegs have diminished interdigitation, and mitochondria are localized apically. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160309
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  • 93
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170101
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  • 94
    Digitale Medien
    Digitale Medien
    Distribution and morphology of motoneurons innervating different muscle fiber types in an amphibian muscle complex (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 327-338 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The distribution and morphology of motoneurons innervating specific types of muscle fibers in the levator scapulae superior (LSS) muscle complex of the bullfrog (Rana catesbeiana) and tiger salamander (Ambystoma tigrinum) were studied by retrograde labelling with cholera toxin-conjugated horseradish peroxidase (CT-HRP). The LSS muscle complex in both of these amphibians has a segregated pattern of muscle-fiber types (tonic; fast oxidative-glycolytic twitch [FOG]; fast glycolytic twitch [FG]) along an anteroposterior axis. The entire motor pool was labelled by injection of CT-HRP into the whole LSS muscle complex. The motoneurons innervating specific fiber types were labelled by injection of CT-HRP into certain muscle regions. The organization of the motoneuron pool of the LSS complex of both species was arranged in two columns - one ventrolateral and one medial. In bullfrogs, the ventrolateral column contains motoneurons innervating FG and tonic fiber types and the medial column contains motoneurons innervating FOG fiber types. In tiger salamanders, the ventrolateral column contains motoneurons innervating FG fiber types and the medial column contains motoneurons innervating FOG and tonic fiber types. The different motoneuron types also have different soma sizes and patterns of dendritic arborization. In both species, FG motoneurons are the largest, whereas FOG motoneurons are intermediate in size and tonic motoneurons are the smallest. In bullfrogs, the main dendrites of FG motoneurons extend into the dorsolateral and the ventrolateral gray matter of the spinal cord, whereas the dendrites of FOG motoneurons extend into the ventral and medial cord. In the tiger salamander, dendrites of FG motoneurons extend into the ventrolateral spinal cord and dendrites of the FOG motoneurons extend more generally into the ventral cord. Dendrites of tonic motoneurons in both amphibians were small and short, and difficult to observe. These results establish that motoneurons innervating different types of muscle fibers in the LSS muscle complex are segregated spatially and display consistent morphological differences. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160308
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  • 95
    Digitale Medien
    Digitale Medien
    Ultrastructure of the cardiac and pyloric glands of the gastric mucosa of the South African hedgehog, Atelerix frontalis (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 351-359 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The cardiac and pyloric glands in the gastric mucosa of the South African hedgehog, Atelerix frontalis, are described. The cardiac area of the stomach contains proper cardiac glands and lacks undifferentiated fundic glands. The cardiac glands are simple tubular, coiled, and lined with columnar cells ultrastructurally similar to those of the gastric surface epithelium. Secretory granules with varying electron densities fill the apical cytoplasm of these cells. In contrast to other mammals, these glands lack mucous neck cells. The neck of the pyloric glands contains only a single cell type, whereas the basal regions of these glands contain “light” and “dark” cells. The secretory granules in the “dark” cells and the pyloric neck cells have a moderate electron density and often contain an electron dense core. An electron-lucent cytoplasm with numerous polysomes is characteristic of the “light” cells. Some “light” cells contain electron-dense granules in the apical cytoplasm. The presence of only neutral mucins in the cardiac gland cells denotes the absence of mucous neck cells. The acidic mucins within the pyloric neck cells seem to indicate that these cells are mucous neck cells, whereas the neutral mucins within the basally located pyloric gland cells show at least a partial functional difference from the pyloric neck cells. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052160310
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  • 96
    Digitale Medien
    Digitale Medien
    Jaws and teeth of american cichlids (Pisces: Labroidei) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 1-36 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The morphology of the upper, lower, and pharyngeal jaws is very similar among American cichlids. Common conditions are: (1) the presence of a premaxillary dentigerous arm shorter than the ascending arm (exceptions are Astronotus, Cichla, and Crenicichla semifasciata), (2) a narrow coulter area; in contrast, a broad coulter area is found in the Crenicichline Group, in certain chaetobranchines, and in Apistogramma, (3) the mandibular sensory canal exists to the skin through five or six simple pores; in contrast, it exits through numerous small pores that increase in number during ontogeny in the Chaetobranchine Group, certain crenicichlines, such as Cichla, Crenicichla lepidota, Crenicichla proteus, and Crenicichla vittata, and certain genera of the Cichlasomine Group A, such as Caquetaia, Petenia, Neetroplus, and “Cichlasoma,” and (4) the premaxilla and dentary of American cichlids commonly bear unicuspid, conical teeth with a few exceptions such as Neetroplus (with scraping blade teeth) and “Cichlasoma” facetum, “C.” cyanoguttatum, “C.” guttulatum, and “C.” spilurum (with bicuspid [hooked] teeth). In contrast to the near uniformity of the upper and lower jaws, the upper and lower pharyngeal jaws present a great diversity of tooth shapes. At least seven types are found in American cichlids; usually, several types exist on a single tooth plate, but the combination of tooth types differs among some genera.The pharyngobranchial 4 tooth plate has significant evolutionary transformations in labroids. The caudal margin of the pharyngobranchial 4 tooth plate bears the frayed zone in cichlids and embiotocids. The presence of a broad frayed zone bearing one to seven concavities represents a synapomorphy for the family Cichlidae, whereas a deep, narrow frayed zone is a synapomorphy of Embiotocidae. The absence of the frayed zone is a synapomorphy of Pomacentridae, whereas the loss of the pharyngobranchial 4 is a synapomorphy of Labridae. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170102
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  • 97
    Digitale Medien
    Digitale Medien
    Fine structure of the nephridial muscle layer cells of Phascolosoma granulatum (Sipuncula) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 45-54 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The nephridial muscle layer of Phascolosoma granulatum consists of a network of longitudinal and circular cells separated by connective tissue matrix. The muscle fibers are densely packed with thick and thin myofilaments, among which are scattered cytoplasmic dense bodies. The nucleus and noncontractile cytoplasmic organelles occupy a lateral projection from the contractile portion of the fiber. Cytoplasmic dense bodies are the result of a clustering of an indeterminate number of the thin actin filaments that fill the cytoplasm between thick filaments. Attached to the cytoplasmic face of the cell membrane are membrane-associated electron-dense plaques. These sites are linked to the contractile myofilaments by narrow filamentous bridges. Extracellular narrow filaments extend from these plaques to collagen fibers of the connective tissue matrix. Differences in length of the dense plaques may be related to differences in thick myofilament diameter in three types of muscle fiber, types A, B and C, statistically distinguished by mean fiber size differences. The plaques may serve as connecting links for the transmission of tension from contractile units to the connective tissue of the muscle layer. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170104
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  • 98
    Digitale Medien
    Digitale Medien
    Muco-follicle cells of the jelly coat in the oocyte envelope of the sheatfish (Silurus glanis L.) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 37-43 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: During early vitellogenesis of the oocytes of Silurus glanis, the follicular cells proliferate, their epithelial organization becomes disrupted, and they transform into an irregularly structured large mass of cells engaged in intensive secretory activity. They contain nuclei, rough endoplasmic reticulum, Golgi bodies, and secretory inclusions termed “acorn bodies,” which are synthesized in the cytoplasm. The acorn bodies have two components: an electron-dense cap and a moderately electron-dense body. As development proceeds, the acorn bodies become modified into spherules of mucous material, the mucosomes. The electron-dense part persists as a small calotte or crescent often irregularly structured at the periphery of the mucosome, and fragments of it are dispersed into the interior of the mucosomal body. The mucosomes are membrane-bound and contain small granules, 55 nm in diameter.At the end of vitellogenesis, the follicle cells are filled with mucosomes, and cytoplasmic residua can only sparingly be observed among them. Oocytic microvilli extend through the zona radiata and intermingle with follicular cell processes in the cleft between the zona radiata and the belt of mucosomes during growth of the oocyte. Capillaries develop in connective tissue of the theca layer as vitellogenesis proceeds. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170103
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  • 99
    Digitale Medien
    Digitale Medien
    Scaling of cursoriality in mammals (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 55-63 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Data on limb bone lengths from 64 mammalian species were combined with data on 114 bovid species (Scott, '79) to assess the scaling of limb lengths and proportions in mammals ranging from 0.002 to 364 kg. We analyzed log-transformed data using both reduced major axis and least-squares regression to focus on the distribution across mammals of two key traits - limb length and metatarsal/femur ratio - associated with cursorial adaptation. The total lengths of both fore and hindlimbs scale in a manner very close to the M0.33 predicted by geometric similarity. Thus the relative limb lengths of large mammals, including bovids, generally regarded among the most cursorial of mammals, are very similar to those of the rodents and insectivores in this sample. Metatarsal/femur ratio also shows little change with changing mass, although bovids tend to have relatively longer metapodials than do other families in the sample. We argue that many of the remaining morphological traits associated with cursoriality (e.g., reduction in joint mobility and number of distal limb bone elements) promote cursoriality only at large body sizes. These results lead us to question the general perception that cursoriality is most widespread among large mammals. We also suggest that discussions of cursoriality should focus explicitly on the two partially independent aspects of performance that are otherwise confounded under this general term - speed and the ability to cover substantial distance. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170105
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  • 100
    Digitale Medien
    Digitale Medien
    Histomorphometry of immature rat testis after heating (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 65-74 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The scrotal testes of albino rats aged 35 and 45 days were immersed in water at constant temperatures of 43°C, 44°C, or 45°C for periods of 15-45 min in a special heating device. At an age of 60 days, the rats were mated in individual cages with two primiparous rats each. At an age of 90 days, they were killed and their testes were histologically processed. Rats with testes that had been subjected to heating when the animals were 45 days old showed both alterations of the seminiferous tubules and a decrease in fertilizing capacity. The effect of heat was greater in animals at 45 than at 35 days of age. In heat-treated testes, tubules contained PAS-positive concretion, sometimes engulfed by macrophage-derived giant cells and multinucleate cells derived from spermatids that failed to separate during spermiogenesis. The decrease in testicular volume observed after heat treatment was due mainly to reduced parenchymal volume. Thermic lability of seminiferous stem cells increases with age until adulthood, and recovery from heat injury declines. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170106
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