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  • 1995-1999
  • 1985-1989  (1,661)
  • 1910-1914
  • 1987  (1,661)
  • Life and Medical Sciences  (1,644)
  • gene expression
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Years
  • 1995-1999
  • 1985-1989  (1,661)
  • 1910-1914
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 43 (1987), S. 741-750 
    ISSN: 1420-9071
    Keywords: Hybridization histochemistry ; hybridocytochemistry ; in situ hybridization ; gene expression ; histochemical hybridization ; nucleic acid hybridization ; histocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The location of gene expression by hybridization histochemistry is being applied in many areas of research and diagnosis. The aim of this technique is to detect specific mRNA in cells and tissues by hybridization with a complementary DNA or RNA probe. Requirements for optimal specificity, sensitivity, resolution and speed of detection may not all be encompassed in one simple technique suitable for all applications, thus appropriate procedures should be selected for specific objectives. With reference to published procedures and our own extensive experience, we have evaluated fixatives, probes, labels and other aspects of the technique critical to the preservation and hybridization in situ of mRNA and detection and quantition of hybrids.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 78 (1987), S. 3-8 
    ISSN: 1573-4919
    Keywords: polyamines ; RNA polymerase ; transcription ; gene expression ; mycobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract All three polyamines — putrescine, spermidine and spermine stimulated the activity of mycobacterial RNA polymerase in vitro although the concentration required for maximal stimulation was different for each of the amines. Spermidine and spermine showed a biphasic effect on the enzyme activity. Stimulation of RNA synthesis by spermidine occurs only at higher DNA template/enzyme ratio. Spermidine stimulates RNA synthesis by acting on the elongation phase of RNA synthesis but it had no effect on initiation phase. Addition of mycobacterial RNA to the assay mixture resulted in the inhibition of RNA polymerase activity and this inhibition could be reversed by spermidine suggesting that spermidine stimulates transcription by binding to nascent RNA and thus destabilizing the short DNA-RNA hybrid region.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 75 (1987), S. 61-70 
    ISSN: 1573-4919
    Keywords: gene expression ; development ; tissue-specific expression ; cell cycle-dependent genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract 4F1, 2A9 and 2F1 represent three of a number of cDNA sequences which have been identified because their cognate RNAs markedly increase when quiescent cells in culture are stimulated with serum. Studies using a variety of cell culture systems have shown that the expression of these genes is modulated by various growth factors and mitogens and thus such genes are considered to be ‘growth-associated.’ Thus far, little information has been obtained with these in vitro systems about the function of these genes. In an attempt to begin to elucidate the role of these genes (if any) in the physiology of the normal cell, we have analyzed the levels of 4F1, 2A9 and 2F1 transcripts in a variety of differentiated organs and tissues of adult and fetal rats. Our results show that each of these growth-associated genes exhibits its own unique pattern of expression, unrelated to the proliferative activity of the tissue. These data suggest that these genes most likely do have specific functions in normal tissue in addition to their role in the induction of DNA synthesis in quiescent cells in culture.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 7 (1987), S. 955-963 
    ISSN: 1573-4935
    Keywords: gene expression ; GC box ; negative regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A DNA control sequence T G GGGCGG AAT GGC , or the “GC” box, has been described in the promoter regions upstream of a number of eukaryotic genes transcribed by polymerase II (for review, see Dynan, W. S. and Tjian, R.,Nature 316:774, 1985). The “GC” box can occur in single or multiple copies and is the binding site for a protein factor, Spl, which activates initiation of transcription. We have observed in the rainbow trout protamine gene 3′ to the TATA box, three “GC” boxes spaced at 80 bp intervals. The first is 5′ to the cap site and possesses the ability to “silence” transcription from the protamine promoter in constructs linking this promoter to the bacterial chloramphenicol acetyl transferase (CAT) coding sequence following transfection to COS-1 cells. A model is proposed to account for the silencing of the protamine gene in all tissues except developing sperm cells.
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  • 5
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA/RNA hybridization ; gene expression ; marker rescue ; nopaline-synthase ; plant tumor cells ; Ti-plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell wall regenerating protoplasts from soybean cells kept in suspension culture were cocultivated with bacteria which were derived from the nopaline strain C58 of Agrobacterium tumefaciens. When the bacteria carried an oncogenic Ti-plasmid, about 5% of the surviving protoplasts were able to form calli on hormone-free agar in contrast to controls, where bacteria without Ti-plasmid were applied, and where no calli were formed. After isolation of DNA from hormone-independently growing cells further evidence for transformation was obtained by hybridization to Ti-plasmid specific RNA and by rescue of a segment with a bacterial resistance gene which had been inserted before into the T-DNA. Transfer of T-DNA harboring a neomycin-resistance gene activated by the nos-promoter resulted in calli growing on kanamycin. Verification of segments located at the left and the right part of the T-DNA indicated the presence of its entire length in transformed soybean cells. Expression of T-DNA genes was measured by the assay of nopaline-synthase. Cells cultured on agar had a much higher level of nopaline-synthase than fast growing cells in suspension culture. Transferring them to agar or treatment with azacytidine strongly increased synthesis of nopaline-synthase indicating a reversible repression presumably via a methylation mechanism.
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  • 6
    ISSN: 1573-5028
    Keywords: cucumber ; gene expression ; hydroxypyruvate reductase ; light regulation ; peroxisomal enzymes ; serine:glyoxylate aminotransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of peroxisomal enzymes in cotyledons of cucumber seedlings is strongly dependent on light. In light-grown seedlings, activities of two peroxisomal enzymes, hydroxypyruvate reductase (HPR) and serine: glyoxylate aminotransferase (SGAT), were barely detectable until three days postimbibition, after which time both activities increased rapidly and linearly for at least three days. In the dark, the activities of these enzymes increased slightly over the same time period, but only to about 5% to 10% of 7-day light-induced levels. When 51/2-day dark-grown seedlings were transferred into white light, activities of HPR and SGAT began to increase after approximately 8 h. HPR protein was shown by an immunoprecipitation assay to increase concurrently with enzymatic activity in both light- and dark-grown cotyledons. Immunoblotting results suggested that the amounts of SGAT-A and SGAT-B, the two subunits of SGAT, also developed along with SGAT activity. The relative levels of translatable mRNAs encoding HPR, SGAT-A, and SGAT-B were also light-dependent, and increased with a developmental pattern similar to enzyme activity and protein levels in light- and dark-grown cotyledons. In 51/2-day dark-grown cotyledons that were transferred to the light, translatable mRNAs for SGAT-A and SGAT-B began to increase within 1 h of illumination and continued of increase rapidly and linearly for the next 24 h in the light to a new steady-state level that was 45 times that of dark controls. Translatable HPR mRNA exhibited a biphasic pattern of accumulation, with a three-fold increase during the first 6 h of illumination, followed by an additional six-fold increase between 8 and 24 h. The accumulation of translationally active mRNA for both enzymes preceded the accumulation of the corresponding protein and enzyme activity by about 8 h. Our data suggest that the rise in enzyme activity depends on an increase in translatable mRNA for these enzymes and is regulated at a pretranslational level, most likely involving transcription of new mRNA.
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  • 7
    ISSN: 1573-5028
    Keywords: gene expression ; nitrogen fixation ; nodulins ; Phaseolus vulgaris ; Rhizobium ; root-nodule development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The identification of some nodule-specific host proteins (nodulins) from common bean (Phaseolus vulgaris L.), a tropical ureide-transporting legume, is described. Particularly, the existence and developmental expression of several abundant nodule-specific transcripts of P. vulgaris are shown, including leghemoglobin, nodulespecific uricase and a group that in vitro translates into a cluster of about 30 kDa products. The expression pattern of nodulins in effective (Fix+) nodules compared to ineffective (Fix-) ones is also presented. The modified expression of main nodulins observed between these nodules indicates that different levels and/or factors associated with their regulation are involved. The intracellular infection by Rhizobium as a decisive step in the induction of some P. vulgaris nodulins is discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 9 (1987), S. 547-563 
    ISSN: 1573-5028
    Keywords: acetate ; blue light ; Chlamydomonas reinhardtii ; chlorophyll a/b-binding protein gene ; gene expression ; LHCP gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Chlamydomonas reinhardtii, the chlorophyll a/b-binding proteins of photosystem II are encoded in the nucleus by a small family of genes. We have studied the expression of one gene, which we call cabII-1, in a green-in-the-dark strain, which can synthesize chlorophyll in the dark or light, and in a yellow-in-the-dark mutant strain, which is able to make chlorophyll only in the light. In light/dark synchronized cultures of both strains, cabII-1 mRNA abundance increases during the first 6 h of a 12-h light phase, remains high for several hours, then declines. A variety of illumination conditions have been used to analyze the cabII-1 mRNA increase: continuous or intermittent red, blue, or white light, with or without 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of photosystem II. Our results suggest that light induces increased cabII-1 transcript abundance in two ways: 1) by virtue of its role in the light reactions of photosynthesis and 2) by a blue lightstimulated mechanism which is independent of photosynthesis. We have also examined the role of acetate in regulating cabII-1 mRNA levels in the dark. In both green- and yellow-in-the-dark strains, 15 mM Na-acetate, added to synchronized cells in the dark, induces an increase in cabII-1 mRNA abundance with a temporal accumulation pattern very similar to that induced by continuous white light. We suggest that by providing an energy source, acetate stimulates cellular growth, cell cycle progression, and increased cabII-1 mRNA abundance. Interestingly, in cells exposed to light, acetate inhibits the light-induced increase in cabII-1 mRNA abundance by a mechanism which is not yet understood.
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  • 9
    ISSN: 1573-5028
    Keywords: abscisic acid ; aleurone layer ; α-amylase ; gene expression ; gibberellic acid ; isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The treatment of barley aleurone layers with gibberellic acid (GA3) results in the synthesis of two groups of α-amylase isozymes. Addition of abscisic acid (ABA) at the same time as GA3 inhibited the synthesis of both groups of isozymes. However, midcourse ABA addition (12 h or later after GA3) had a more inhibitory effect on the high pI α-amylase group than on the low pI α-amylase group. This midcourse inhibition was detectable within 2 h of ABA addition. Northern analysis results using cDNA probes for the high pI and low pI α-amylase groups paralleled the protein synthesis results for both isozyme groups. High pI α-amylase mRNA levels began to decrease within 2 h of midcourse ABA treatment and were less than 10% of the original level by 4 h. The levels of low pI α-amylase mRNA were decreased less by midcourse ABA addition than were high pI mRNA levels. Cordycepin and cycloheximide blocked the effects of midcourse ABA addition on α-amylase mRNA. These observations indicate that ABA inhibits α-amylase expression at the pretranslational level and that protein and RNA synthesis are required for midcourse ABA action to occur. Our results also show that α-amylase mRNA, which has been thought to be very stable, is degraded after midcourse ABA treatment.
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  • 10
    ISSN: 1573-5028
    Keywords: plant transformation ; CaMV promoters ; gene expression ; protein stability ; beta-conglycinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene encoding the α′-subunit of β-conglycinin was ligated to the 19S and 35S promoters of Cauliflower Mosaic Virus and introduced into petunia plants on a disarmed Ti-plasmid using Agrobacterium tumefaciens. Transformed cells were regenerated into whole plants and ummunoreactive polypeptides and hybridizable, polyadenylated mRNA were detected in transformed tissues. Expression from the 35S promoter was 10 to 50 times greater than expression from the 19S promoter. The level of immunodetectable polypeptides was greater in seeds than in leaves or callus tissue. In addition, the pattern of α′-polypeptide breakdown products was distinctive in seeds and leaves. We conclude that in seeds the higher levels of the α′-polypeptide reflect enhanced stability of this protein.
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  • 11
    ISSN: 1573-5028
    Keywords: hypersensitive response ; Brassica campestris ; Xanthomonas campestris pv. vitians ; mRNA induction ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Xanthomonas campestris pv. vitians, a pathogen of lettuce, elicits a hypersensitive response within 12 hours of inoculation into Brassica leaves, characterized by tissue collapse, loss of membrane integrity, vein blockage and melanin production. In contrast, the compatible pathogen, X. c. pv. campestris, has no visible effects on leaves for 48 hours, after which inoculated areas show chlorosis which eventually spreads, followed by rotting. mRNA was prepared from leaves inoculated with suspensions of both pathovars or with sterile medium up to 24 hours following inoculation. In vitro translation of total and poly A+ RNA in rabbit reticulocyte lysate in the presence of 35S methionine followed by separation of the polypeptide products by 2D-PAGE, allowed comparison of the effects of these treatments on plant gene expression. Major changes in gene expression were observed as a consequence of the inoculation technique. In addition, after inoculation with X. c. vitians, up to fifteen additional major polypeptides appeared or greatly increased by four hours. Some of these had disappeared by nine hours and several more had appeared. No major polypeptides disappeared or decreased greatly in intensity following inoculation with X. c. vitians.
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  • 12
    ISSN: 1573-5028
    Keywords: coordinate regulation ; Cucurbita phytochrome cDNA ; gene expression ; light regulation ; multiple transcripts ; regulatory photoreceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated several cDNA clones for phytochrome from a dicot, Cucurbita pepo L. cv. Black Beauty (zucchini), and have used them to study the regulation of Cucurbita phytochrome mRNA levels. A cDNA library was constructed from poly(A)+ RNA isolated from etiolated Cucurbita hypocotyl hooks and enriched for phytochrome mRNA by size fractionation. This library was screened with a 32P-labeled fragment isolated from an Avena phytochrome cDNA clone. Several putative phytochrome clones were isolated and mapped by restriction endonuclease analysis. On the basis of this analysis there is no evidence for the expression of multiple phytochrome genes in Cucurbita. Recent sequence analysis has confirmed that the largest of these clones, pFMD1 (∼3.6 kb), does indeed encode phytochrome and that it contains the entire amino acid coding sequence for Cucurbita phytochrome (33). RNA blot analysis has revealed that two polyadenylated phytochrome transcripts (∼5.6 kb and ∼4.2 kb) are present in both cotyledons and hypocotyl hooks of Cucurbita. In etiolated Cucurbita seedlings given a saturating pulse of red light, the abundance of both transcripts coordinately declines to 50–60% of the dark levels within 3 h and reaccumulates to dark levels within 24 h. Reversal of induction of this response by a far-red light pulse immediately following red light treatment is not observed, which is in contrast to the far-red reversibility of the red light promoted decrease in phytochrome mRNA abundance observed in Avena (6). Etiolated seedlings transferred to continuous white light also show a coordinate decrease in the levels of the two RNAs to ∼40% of the dark levels within 3 h. The magnitude of the light-induced decline in phytochrome mRNA abundance in Cucurbita is substantially less than the decrease previously reported for Avena (6).
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Cancer and metastasis reviews 6 (1987), S. 503-520 
    ISSN: 1573-7233
    Keywords: animal models ; chemotherapy ; gene expression ; metastasis ; tumour progression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cancer chemotherapy is currently undergoing an intensive reappraisal because of its unimpressive performance against the major common cancers. There are a number of possible reasons for this lack of success; one considered here is that under some circumstances anti-neoplastic drug treatment actually increases the malignant behaviour of tumours. Support for this idea comes mainly from experimental studies in which drug treatments increased metastatic spread. Investigation of this phenomenon shows that drug induced modifications of the host, including immunosuppression and vascular damage, can indeed facilitate metastasis. In addition, new data are presented demonstrating that the direct action of drugs on the tumour cells themselves can have similar enhancing effects. The possible mechanisms underlying such direct effects are discussed and the ability of anti-cancer drugs to cause genetic mutations, amplify genes, and alter gene expression are considered. While the nature and extent of this facilitation of tumour malignancy is not fully understood, it is suggested that this possibility should be considered in the design of treatment protocols.
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  • 14
    ISSN: 1572-994X
    Keywords: EBV ; gene expression ; immortalization ; cDNA cloning ; Northern blot hybridization ; tonsil lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two infection systems have been introduced in order to study viral gene expression at the initial period of Epstein-Barr virus (EBV) infection which leads to immortalization. The data indicate that major viral gene expression in tonsil lymphocytes at 2 days post-infection (p.i.) with EBV is very similar to that observed in latently infected cells. Both tonsil lymphocyte and BJAB cell (lymphoblastoid cells free of EBV genome) infection with EBV induced similar viral gene transcription. Twelve cDNA clones were prepared from poly(A) RNA of tonsil lymphocytes infected with EBV 2 days p.i. by hybridization with BamHI fragments of EBV DNA. Some cDNAs were derived from primary transcripts of the BamHI-WYHK region, suggestive of splicing of a large transcript. It is possible that a number of cDNA clones may be derived from cellular genes. The derivation of these cDNA clones is being studied.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 8 (1987), S. 251-264 
    ISSN: 1573-5028
    Keywords: chromatin structure ; DNase I hypersensitivity ; gene expression ; sucrose synthetase ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The local chromatin structure of the Shrunken-1 (Sh) gene of maize was probed by analyzing DNase I hypersensitivity. Sh encodes the gene for sucrose synthetase, a major starch biosynthetic enzyme, which is maximally expressed in the endosperm during seed maturation. In addition to general DNase I sensitivity, specific DNase I hypersensitive sites were identified in endosperm chromatin that mapped near the 5′ end of the Sh gene. The pattern of hypersensitive sites and their relative sensitivity were altered in other non-dormant tissues that produce little or no enzyme. However, some changes in chromatin structure appear to be independent of Sh gene expression and may reflect general alterations associated with plant development. The chromatin structure of several sh mutations, induced by Ds controlling element insertions, was also analyzed. Although the insertions perturbed expression of the gene, there were no notable effects on local chromatin structure.
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  • 16
    ISSN: 1573-5028
    Keywords: Bradyrhizobium ; gene expression ; nodulin ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro translation products of total RNA isolated from soybean nodules at successive stages of nodule development were analyzed by two-dimensional gel electrophoresis. In that way the occurrence of over 20 mRNAs specifically transcribed from nodulin genes was detected. The nodulin genes could be divided into two classes according to the time of expression during nodule development. Class A comprises at least 4 nodulin mRNAs which are found when a globular meristem is present in the root cortex. These class A nodulin genes have a transient expression. Class B nodulin genes are expressed when the formation of a nodule structure has been completed. Bradyrhizobium japonicum nod + fix-mutants, with large deletions spanning the nif H,DK region, still induced nodules showing normal expression of all nodulin genes, indicating that the nif H,DK region is not involved in the induction of nodulin genes. In nodules induced by Bradyrhizobium japonicum nod + fix-mutant HS124 the bacteria are rarely released from the infection thread and the few infected cells appear to be collapsed. All class A and class B nodulin genes are expressed in HS124 nodules with the exception of 5 class B genes.
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  • 17
    ISSN: 1573-5028
    Keywords: potato tuber ; elicitor ; arachidonic acid ; cDNA cloning ; gene expression ; PR proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of messenger RNAs in potato tuber discs was analysed during the hypersensitive response induced by treatment with the biotic elicitor arachidonic acid. In vitro translation of polysomal poly(A)+ RNAs indicated that the accumulation of some sixteen mRNAs varied following treatment with arachidonic acid, and that the level of thirteen of these was increased. Two cDNA closes (pSTH-1 and-2) were isolated from a library of elicitor-treated tissue cDNAs. Northern blot analysis using these clones as molecular probes indicated that the levels of at least two mRNAs were markedly increased after elicitor treatment. In hybrid-released translation experiments, each of the cDNA clones selected more than one mRNA. Translation of these mRNAs yielded two polypeptides of Mr 45 000 (for the pSTH-1 clone), and three polypeptides of Me 17 000 (for the pSTH-2 clone). The low molecular weight polypeptides may correspond to potato pathogenesis-related (PR) proteins.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 191 (1987), S. 17-23 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies have examined the isometric contraction properties of the two heads of the cat flexor carpi ulnaris acting as a single unit. In this study, the contraction properties and fiber architecture of each head of the flexor carpi ulnaris were determined separately and related to previous reports on the histochemical characteristics of this muscle. The morphology of retrograde-labeled motor nuclei for the two heads of the muscle was also examined. The humeral head had a significantly longer contraction time (48 msec) than the ulnar head (36 msec) as well as a significantly lower tetanic fusion frequency (28 Hz vs. 35 Hz). The maximum tetanic tension per gram of muscle tissue was 71% greater in the ulnar head. Motoneurons of the flexor carpi ulnaris formed a column 12 mm long and 0.5 mm wide in the center of the ventral grey in spinal segments C8 and T1. The ulnar head had α-motoneurons with greater soma diameters than those in the humeral head. The smaller soma diameter, slower contraction time, and weaker contraction in the humeral head correlate with the preponderance of oxidative-metabolic muscle fiber types found in the humeral head by other workers. These correlations suggest that the humeral head plays a major role in maintaining a sustained antigravity tension that prevents the wrist from buckling during standing.
    Additional Material: 1 Ill.
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  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Comparison of metamorphosis of skull and hyobranchial system in two species of neotenic salamanders reveals two different types of neoteny. Ambystoma talpoideum is completely neotenic owing to delayed metamorphosis. Notophthalmus viridescens exhibits limited neoteny as a result of incomplete metamorphosis. Morphological details of neoteny are compared to life history in both species in order to discuss the ecological morphology of the two neotenic strategies. Comparisons to Taricha granulosa, Triturus vulgaris, and Ambystoma gracile indicate that these two strategies are widely employed and may represent familial patterns.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 191 (1987), S. 247-263 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using scanning electron microscopy I determined neuromast number and orientation, neuromast sensory epithelial surface area and relative position, hair cell number per neuromast, hair cell size, and stitch formation in aquatic urodeles. All aquatic salamanders examined (34 specimens, 20 species, 16 genera, nine families) had neuromasts. The basic pattern of neuromast organization was similar in all species, consisting of a single row of circumorbital (supraorbital + infraorbital) neuromasts and anteriorly along the snout two rows of nasal and three rows of maxillary neuromasts. Nasal and maxillary groups consisted of orthogonally oriented neuromasts. Variation in most parameters occured at every taxonomic level, between individuals of the same species, and even on opposite sides of the same individual. Among species, primary neuromast number ranged from 94 to 150, with plethodontids having higher numbers. Despite high intraspecific variation, neuromast number fell into a sufficiently narrow range to be useful systematically. Hair cell number per neuromast was greater in species with larger animals. Hair cell number per neuromast and number of primary neuromasts did not increase with growth. In some species primary neuromasts divided to form secondary neuromasts (together termed a stitch). Two types of stitches-transverse and longitudinal-were formed. Transverse stitches were characteristic of ambystomatids and cryptobranchids, longitudinal stitches were characteristic of proteids and salamandrids. Because transverse stitches are also characteristic of anurans, this trait may be the generalized condition in at least these two amphibian orders. With stitch formation total number of hair cells on the dorsal surface of the head of these animals can be increased over tenfold to almost 20,000. Ecologically, lentic forms tended to form transverse stitches, while lotic forms had single neuromasts in epidermal pits or longitudinal stitches in epidermal grooves. Lotic forms also tended to have more primary neuromasts and more nasal and maxillary neuromasts.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 23-33 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The labral glands of Daphnia consist of three distinct functional units on each side: (1) several cells at the base of the head, (2) two large cells at the base of the labrum and one large cell (cell A) in the median part of the labrum and (3) one large cell (cell B) in the median part of the labrum. These gland cells do not form a syncytium, contrary to reports by previous investigators. With the exception of cell B, they have a well-developed rough endoplasmic reticulum and many active Golgi complexes. The Golgi activity changes during the molt cycle. The Golgi activity of the cells of the head base is different from that of the large cells of the labrum. Since clear exocytotic phenomena were not observed, the secretion can be assumed to flow into the hemolymph after accumulation in the enlarged intercellular spaces. Cell B has a distinctive cytoplasmic ultrastructure the function of which is not yet understood.The four large cells of the labrum are in contact with a duct cell (or several duct cells) characterized by a deep infolding of the plasma membrane. This delimits a narrow lumen, which contains no secretion. No passage of substance is visible from the gland cells to the duct cell(s).
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 63-73 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The adrenergic innervation of structures in the gills of six teleost species was studied with catecholamine fluorescence histochemistry. The species studied were the following: sand flathead, Platycephalus bassensis and blue-spot flathead Platycephalus caeuruleopunctatus (Platycephalidae); smooth toadfish, Tetractenos glaber (Tetraodontidae); Australian short-finned eel, Anguilla australis (Anguillidae); river blackfish, Gadopsis marmoratus (Gadopsidae); and common carp Cyprinus carpio (Cyprinidae).In all species except C. carpio fluorescent components were observed in the branchial nerves in the gill arch.In the arterio-arterial vascular pathway, the afferent and efferent branchial arteries were innervated only in Cyprinus. Fluorescent nerve fibres were found on afferent filamental arteries of all species except A. australis and on many afferent lamellar arterioles of all species except T. glaber. The secondary lamellae were devoid of fluorescent nerve fibres in all species. In Cyprinus and Anguilla, fluorescent nerve fibres were observed on occasional efferent lamellar arterioles. In Cyprinus, there was an additional innervation on the basal one-third of the efferent filamental artery. The innervation of the arteriovenous vascular pathway was similar in all species. Fluorescent nerve fibres were found on nutritive arterioles, and in the core of each filament between the surface epithelium and the wall of the filament venous sinus.Since most of the adrenergic innervation was found on afferent vessels of the arterio-arterial pathway, it is suggested that adrenergic nerves and circulating catecholamines may have distinct functions in the regulation of blood flow through the gills.
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  • 23
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    Journal of Morphology 193 (1987), S. 117-133 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gross dissection, light microscopy, and transmission electron microscopy were used to generate a detailed understanding of the ovarian anatomy of the pipefish, Syngnathus scovelli. The ovary is a cylindrical tube bounded by an outer layer consisting of a smooth muscle wall and an inner layer of luminal epithelium, with follicles sandwiched between the two layers. A remarkable feature of this ovary is a sequential pattern of follicle development. This pattern begins at the germinal ridge with a gradient of follicles of increasing developmental age extending to the mature edge. The germinal ridge is an outpocketed region of the luminal epithelium containing early germinal cells and somatic prefollicular cells. Therefore, the germinal ridge and luminal epithelium share the same ovarian compartment and follicle formation occurs within this compartment. The mature edge is defined as the site of oocyte maturation and ovulation. The outer ovarian wall contains unmyelinated nerve fibers throughout. Longitudinally oriented unmyelinated nerves are also observed near the smooth muscle bundles associated with the mature edge. Oocytes near the mature edge are polarized such that the germinal vesicle (nucleus) is generally oriented toward the luminal epithelium. The sandwichlike organization of the ovary results in follicles that have a shared theca. An extensive lymphatic network is also interspersed among the follicles. Thus, the exceptional features of the pipefish ovary make it particularly well suited for the examination of early events in oogenesis. Specifically, we characterize pipefish folliculogenesis in detail.
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  • 24
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    Journal of Morphology 193 (1987), S. 185-196 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hemocytes of Leiobunum limbatum, Mitopus morio, and Opilio ravennae number from about 8,000 (juveniles) to 41,000 (pregnant females) per microliter of hemolymph. Five different types of hemocytes occur in all three species and both sexes. According to their ultrastructural appearance and their similarities to other arthropod hemocytes these five types are designated as prohemocyte, plasmatocyte, granulocyte, coagulocyte, and spherulocyte. From the ultrastructural point of view the prohemocytes are interpreted as stem cells for plasmatocytes which on their part differentiate into granulocytes. Transitional stages which would indicate the origin of coagulocytes and spherulocytes could not be found.Granulocytes and spherulocytes are interpreted as being storage cells; coagulocytes burst when hemolymph is transferred to a microscopic slide. Plasmatocytes are involved in the removal of dead cells or cell fragments. Plasmatocytes are demonstrated as being able to phagocytize and digest bacteria.
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  • 25
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    Journal of Morphology 193 (1987), S. 225-239 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pituitary glands of adult male lizards (Anolis carolinensis) were studied in an effort to monitor seasonal cytologic changes quantitatively. Cells were identified immunocytochemically and on the basis of ultrastructural characteristics.Electron micrographs of the anterior pars distalis (containing lactotropes, corticotropes, and gonadotropes) of lizards collected in spring and fall were analyzed morphometrically. Lactotropes are the most numerous cell type in this area and occupy the largest volume. They are closely followed by corticotropes. Neither kind of cell undergoes a marked seasonal change in number or size or in the percent of the analyzed volume they occupy. Morphometric and ultrastructural criteria indicate an increased level of activity in all three kinds of secretory cells in the spring, although changes are relatively modest in corticotropes and lactotropes.Gonadotropes occupy less than half the volume of either of the other secretory cells in the analyzed area, but undergo considerable seasonal modification. They are larger (〉 40%) and more numerous (20%) in the spring, and show an increase in biosynthetic organelles at this time. Although the density of secretion granules may be reduced in the enlarged spring gonadotropes, the number of granules per cell may not be altered seasonally.Seasonal changes in the three cell types analyzed are moderate in contrast to the cytologic modifications described in pituitary cells following castration or other experimental procedures. Necrotic cells appear to be a normal component of the pituitary gland of Anolis carolinensis throughout the year.
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  • 26
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    Journal of Morphology 192 (1987), S. 205-215 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Septate junctions develop initially just basad from apical junctional complexes at the apical ends of regenerating gastrodermal cells. The first morphological indication of differentiation of the junction is the appearance of gentle undulations of the plasma membranes of apposing cells. Subsequently dense dots develop at fairly regular intervals at the cytoplasmic surface of one cell, while SER cisternae become localized opposite them near the surface of the apposing cell. The dense dots are associated with bulges which narrow the intercellular space. Later the dense dots are replaced by filaments aligned along the inner leaflet of the parent cell. Strands of amorphous deposits form connections between SER cisternae and the sister membrane on the opposite side of the junction. Ruthenium red staining provides information on precursors which occupy the intercellular space between the apposed plasma membranes. As development of the junction progresses, ruthenium red stains only the newly formed septa but not the interseptal matrix. Regular arrangement of individual septa seems to be completed under the control of V-projections from both of their surfaces. Precursors for the structural material of the septa may be a secretory product derived from the SER. Dense dots and their derived filaments probably serve as reinforcing material for strengthening the cell membrane of the junction.
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  • 27
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    Journal of Morphology 192 (1987), S. 237-246 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Freshly extruded and hardened spermatophores of the spiny lobster, Panulirus interruptus, were compared using light and electron microscopy (EM). The spermatophore is composed of a sperm tube embedded in an acellular matrix. The sperm tube consists of tightly packed spherical cavities in an acellular material within which the sperm lie. The extruded spermatophore is white, soft, and sticky on all surfaces. The highly coiled sperm tube can be seen near the surface of the foot of the spermatophore, which is the side that will attach to the exoskeleton of the female. The opposite surface, the cap, will harden and darken after exposure to seawater. In the soft spermatophore, the matrix surrounding the sperm tube and extending from foot to cap is composed of small (2-μm) granules embedded in a loose weave of filaments. In the hardened spermatophore, the matrix is composed of small (4-μm) empty spheres. At the cap region the matrix darkens, and at the foot the granules dissolve to form a thick layer characterized by vertical striations. The structure of this spermatophore is compared to those spermatophores of other decapods that have been described at the EM level. The chemical composition and possible function(s) of the various components are discussed.
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  • 28
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    Journal of Morphology 193 (1987), S. 35-51 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopy reveal that simple receptor cells in the jaw epithelium of sea urchin pedicellariae are connected by nerve tracts to the neuropile that coordinates jaw movements. The muscles responsible for jaw opening and closure and for flexion of the stem are all innervated in this neuropile. At least two types of vesicles occur at the simple synapses between neurone profiles and at neuromuscular junctions. The muscles include both striated and smooth fibres; however, their distribution varies according to pedicellaria type, and an unexpected arrangement exists in trifoliate pedicellariae.
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  • 29
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    Journal of Morphology 193 (1987), S. 75-89 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the whip spider Heterophrynus elaphus the first pair of legs is specialized to serve sensory functions. The morphology of these “whips” and the sensory organs of their tarsi and tibiae are described using scanning and transmission electron microscopy. The tarsus is normally subdivided into 74 segments and bears 7 types of sensory hairs: bristles, club sensilla, two types of porous sensilla, two types of rod sensilla, and leaflike hairs. In addition there are modified claws, 3 kinds of slit sense organs, a “pit organ,” a “plate organ,” and probably a joint receptor. The tibia is usually subdivided into 33 segments. In addition to bristles the tibia bears 7 trichobothria at constant locations and a lyriform slit sense organ. The functional and systematic implications of these findings are discussed.
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  • 30
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    Journal of Morphology 193 (1987), S. 99-116 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vernalized gemmules of the marine sponge Haliclona loosanoffi were cultured at 20°C, fixed at 24-hour intervals (0-11 days), and processed for light microscopy by using a variety of absorption and fluorescent staining methods. The cytochemistry and morphology of development were compared to the well-studied developmental patterns of freshwater sponges and to the patterns described in the marine sponge Suberites domuncula. The precocious development of H. loosanoffi gemmules involves early morphogenesis occurring within the unhatched gemmule, as opposed to the patterns in freshwater sponges, where most development occurs after the gemmule hatches. Definitive sponge tissue surrounding a single osculum is present 9 days after release from dormancy.
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  • 31
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    Journal of Morphology 191 (1987), S. 1-15 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cat hindlimb contains several long, biarticular strap muscles composed of parallel muscle fascicles that attach to short tendons. Three of these muscles -sartorius, tenuissimus, and semitendinosus -were studied by dissecting individual gold-stained fibers and determining the surface distribution of acetylcholinesterase-stained end-plate zones. In each muscle, fascicles were composed of muscle fibers that ran only part of the fascicle length and tapered to end as fine strands that interdigitated with other tapering fibers within the muscle mass. Most muscle fibers measured 2-3 cm in length. Fascicles of muscle fibers were crossed by short transverse bands of endplates (1 mm wide by 1-5 mm long) that were spaced at fairly regular intervals from the origin to the insertion of the muscle. The endplate pattern suggested that the fiber fascicles were organized into multiple longitudinal strips. In the sartorius, the temporospatial distribution of electromyographic (EMG) activity evoked by stimulating fine, longitudinal branches of the parent nerve confirmed that each strip was selectively innervated by a small subset of the motor axons. These axons appeared to distribute their endings throughout the entire length of the fascicles, providing for synchronous activation of their in-series fibers.
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  • 32
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    Journal of Morphology 191 (1987), S. 49-62 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper offers a model for the normalized length-tension relation of a muscle fiber based upon sarcomere design. Comparison with measurements published by Gordon et al. (′66) shows an accurate fit as long as the inhomogeneity of sarcomere length in a single muscle fiber is taken into account. Sequential change of filament length and the length of the cross-bridge-free zone leads the model to suggest that most vertebrate sarcomeres tested match the condition of optimal construction for the output of mechanical energy over a full sarcomere contraction movement. Joint optimization of all three morphometric parameters suggests that a slightly better (0.3%) design is theoretically possible. However, this theoretical sarcomere, optimally designed for the conversion of energy, has a low normalized contraction velocity; it provides a poorer match to the combined functional demands of high energy output and high contraction velocity than the real sarcomeres of vertebrates.The sarcomeres in fish myotomes appear to be built suboptimally for isometric contraction, but built optimally for that shortening velocity generating maximum power. During swimming, these muscles do indeed contract concentrically only. The sarcomeres of insect asynchronous flight muscles contract only slightly. They are not built optimally for maximum output of energy across the full range of contraction encountered in vertebrate sarcomeres, but are built almost optimally for the contraction range that they do in fact employ.
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  • 33
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    Journal of Morphology 191 (1987), S. 77-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Development and innervation of the lymph heart musculature of chicken, emu, rhea, and duck was studied by electron microscopy at posthatch ages from 3 days to adulthood. Development of innervation was monitored by acetylcholinesterase staining. Horseradish peroxidase was used to determine the extent of the transverse tubule network. Chickens were unusual among these birds in that lymph heart myocytes had already undergone a definitive differentiation and degeneration by 3 days. In ducks and ratite birds, lymph heart myocytes more slowly but progressively differentiate a cytomorphology that does not conform in all characteristics to cardiac or skeletal muscle and even resembles in some aspects, smooth muscle. Myofibrils become the dominant cytoplasmic structure, transverse tubules form ‘internal couplings’ with agranular reticulum cisternae, and ‘external couplings’ are formed between myocytes at myomyal junctions. The myomyal junctions also contain AChE-positive reaction product and some subplasmalemmal vesicles that lack a dense core. The lymph heart myocardium of ducks of 2 weeks demonstrated mitotic figures. In adult ducks the myosatellite cell numbers diminish and a characteristic pattern of myocyte degeneration appears. In juvenile ducks and ratites some myocytes differentiate to conductile cells, much as the conductile myocytes and myofibers of the blood heart. The lymph heart innervation is described, and the role of nerve in differentiation and maintenance of myocyte morphology in the lymph heart is discussed.
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  • 34
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    Journal of Morphology 191 (1987), S. 145-149 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning electron micrographs of microcorrosion casts of the renal vascular system of Pseudemys scripta and Testudo hermanni show fairly well-developed, round glomeruli in the former (mean diameter of casts: 83.1 μm) and fewer but bigger, ovoid glomeruli (mean diameter of casts: 111.1 μm/131.6 μm) in the more arid-adapted. T. hermanni. Furthermore, the intrarenal development of the pertiubular capillary system differs in these two species. These relatively minor morphological differences correlate well with the major differences in the ecology of these species, as well as with physiological data on urine composition from the literature.
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  • 35
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    Journal of Morphology 194 (1987), S. 41-53 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The prominent accessory lobes of Lachi in birds are considered to be marginal nuclei; similar nuclei have been implicated in mechanoreceptive functions in snakes and lampreys. Reptile studies emphasized the involvement of the denticulate ligament with this mechanoreceptive function. This investigation examines the fine structure of the accessory lobes of Lachi in pigeons and their interaction with ligaments for features which might support such a mechanoreceptive function. In the lumbosacral area of the spinal cord, the lateral longitudinal ligaments and the ventral longitudinal ligament are hypertrophied. The ventral transverse ligaments are present only within the lumbosacral segments of the spinal cord and they interconnect with the lateral and ventral longitudinal ligaments. The lateral longitudinal ligament makes intimate contact with the spinal cord, and many glial processes from the spinal cord mingle with and are firmly attached to collagenous fibers of the ligament. The lobes lie dorsal to the lateral longitudinal ligament in the exact area where it interconnects with the transverse ligament. The lobe's multipolar neurons have a number of synaptic contacts but no unusual specializations were noted. Most of each lobe is composed of interdigitating saccular structures filled to varying degrees with flocculent material. The sacs are extensions of the cytoplasm of neuroglial cells, which also give rise to membranes surrounding neuronal processes and the sacs themselves. A possible functional relationship of the lobes and the ligaments of the lumbosacral spinal segments within the vertebral column is described.
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  • 36
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    Journal of Morphology 194 (1987), S. 75-84 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several morphological and functional characteristics of the rat gastrocnemius medialis and tibialis anterior muscle were studied in young, adult, and old rats to assess the influence of growth. Antagonist muscles were studied to determine how changes of muscle architecture and functional characteristics are influenced by the demands of increased body weight and by the specific roles of these muscles in locomotion.Both muscles change drastically, for instance, in muscle length, volume, physiological cross-sectional area aponeurosis length, and their muscular geometry changes allometrically for both muscles. The relationships between muscle length, distance between origin and insertion, tendon length, and tibial length also change with growth. Both muscles are rather pennate, so that the increase of physiological cross-sectional area is a major factor in the determination of muscle length.No significant difference could be shown for fundamental physiological characteristics (i.e., functional characteristics normalized for muscular dimensions such as maximal work per unit volume). The changes of morphological and functional variables of both muscles parallel each other as is apparent from the index of antagonist characteristics, which is constant for all variables studied with the exception of muscle volume and tendon length.Consequently, the considerable and similar changes of TA and GM morphology and functional characteristics that take place during growth from approximately four weeks postnatally is not caused by changes of muscular material but by changes of the amount and architectural arrangement of the material involved.
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  • 37
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    Journal of Morphology 194 (1987), S. 143-161 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Between weaning and adulthood, the length and height of the facial skull of the New Zealand rabbit (Oryctolagus cuniculus) double, whereas much less growth occurs in the width of the face and in the neurocranium. There is a five-fold increase in mass of the masticatory muscles, caused mainly by growth in cross-sectional area. The share of the superficial masseter in the total mass increases at the cost of the jaw openers. There are changes in the direction of the working lines of a few muscles. A 3-dimensional mechanical model was used to predict bite forces at different mandibular positions. It shows that young rabbits are able to generate large bite forces at a wider range of mandibular positions than adults and that the forces are directed more vertically. In young and adult animals, the masticatory muscles differ from each other with respect to the degree of gape at which optimum sarcomere length is reached. Consequently, bite force can be maintained over a range of gapes, larger than predicted on basis of individual length - tension curves. Despite the considerable changes in skull shape and concurrent changes in the jaw muscles, the direction of the resultant force of the closing muscles and its mechanical advantage remain stable during growth. Observed phenomena suggest that during development the possibilities for generation of large bite forces are increased at the cost of a restriction of the range of jaw excursion.
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  • 38
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    Journal of Morphology 194 (1987), S. 195-207 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The exocrine glandular system of the nymphs and the adults of Dysdercus cingulatus were studied. The D. cingulatus nymphs present 3 dorso-abdominal glands (lying under the 3rd, 4th, and 5th abdominal terga) and a pair of dorso-lateral pygidial glands on the pygidium (tergum 8). Histological and ultrastructural studies show that the upper and lower walls of the dorso-abdominal glands differ in structure; 3 types of cells were described: epidermal cells, unicellular secretory cells, and multicellular secretory units. Each of these exocrine glands plays an important part in the behavior of the nymphs (gregariousness, alarm, defense). The morphology of the various glands is discussed, and the chemistry of their secretions and their biological functions are considered.
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  • 39
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    Journal of Morphology 191 (1987), S. 25-36 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The major anatomical divisions of the cerebellum of the European eel, i.e., corpus cerebelli, lobus vestibulolateralis, and valvula, were studied morphologically and morphometrically. There were differences in cerebellar cytoarchitecture and gross morphology in two stages of the eel life cycle, the trophic stage (yellow eel), and the reproductive stage (silver eel), which are characterized by different degrees of swimming activity. The principal differences between silver and yellow eels in the cytoarchitecture of the corpus cerebelli and the lobus vestibulolateralis were in distribution of Purkinje or Purkinje-like cells in the molecular layer, which is wider in silver eels, in part because of a decreased thickness of the granular cell layer. In the silver eel, the scattering of Purkinje cells was more evident in the lobus vestibulolateralis where the molecular layer is also thicker. The data indicate the transition from the yellow eel to the silver eel is characterized by a migration of granule cells from the ganglionic cell layer to the internal granular layer and by a further development of molecular layer components, e.g., parallel fibers, Purkinje-cell dendrites, etc. In contrast, the thickness of the granular layer and of the Purkinje cell layer, limited to the lower part of the valvula, decreased. There is also a slight increase of cerebellar volume in the silver eel. The volume of the lobus vestibulolateralis was constant. Hypertrophy of the valvula and eminentiae granulares is observed and is due to the migration of cells from the granular layer of the corpus cerebelli whose volume slightly decreases. Perhaps the lobus vestibulolateralis also contributes to the increased volume of eminentiae granulares. Our findings suggest that the cerebellum continues to develop during the passage from the trophic to the reproductive stage of the eel. The appearance of new afferents from the lateral line which becomes more visible in the silver eel probably completes cerebellar ontogeny.
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  • 40
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    Journal of Morphology 191 (1987), S. 107-107 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 41
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    Journal of Morphology 191 (1987), S. 131-144 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Xenopus laevis froglet forelimbs normally respond to amputational injury by forming a heteromorphic cartilaginous rod-shaped outgrowth. However, partial denervation of a forelimb by ablation of the N. radialis or the N. ulnaris, followed in 2 days by amputation through the mid radius-ulna, results in a size deficiency of the regenerative outgrowth 14 and 21 days postamputation. The decreasing quantity of forelimb innervation, as a result of partial denervation by 55 or 45%, apparently has a graded effect on the cell population and on the extent of cartilage development in the outgrowth. As a consequence of amputational injury, a nerve independent response of the periosteum was also found. This response produced considerable thickening in the periosteum and was due to cell proliferation in both the control and denervated cases.
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  • 42
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    Journal of Morphology 191 (1987), S. 193-204 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nerve pathways in the praesoma are described for a member of the class Eoacanthocephala for the first time. Eleven nerves, five paired and one single, are traced from the cerebral ganglion to their associations with the musculature of the body wall, neck sense organs, and the musculature of the proboscis wall and the invertor muscles of the proboscis. The structure and location of the stutzzelle and series of nerve endings in the hypodermis of the body wall and at the apex of the proboscis are described.
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  • 43
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    Journal of Morphology 191 (1987), S. 215-216 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 44
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    Journal of Morphology 191 (1987), S. 225-232 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Serial transverse paraffin sections of intrafusal muscle fibers of spindles from the extensor pollicis and the extensor digitorum communis of ducks show that only one type of intrafusal muscle fiber exists, based on the mid-equatorial nucleation pattern, diameter, and length. Although the overall range in fiber diameter at the mid-equatorial region is between 4.2-20.0 μm, the average caliber is 10.4 ± 3.18 μm (S.D.) for spindles of the extensor pollicis and 9.3 ± 2.11 μm (S.D.) for spindles of the extensor digitorum communis muscles. The range in spindle length for the extensor pollicis is 290-2,090 μm, average 1,120 ± 569 μm (S.D.), and for the extensor digitorum communis 1,160-2,500 μm, average 1,745 ± 367 μm (S.D.). Therange in number of fibers per spindle for the extensor pollicis muscle is 5-12, average 8.2, and for the extensor digitorum muscle it is 1-11. In the extensor digitorum communis, there appear to be two groups, based on fiber number. Spindles of one group have a range of 5-11 fibers per spindle with an average of 7.2, whereas the second group has a range of 1-4 with an average of 2.7 fibers per spindle. The second group of spindles constitutes 52.5% of the 40 spindles studied, and of these 7.5% were monofibril spindles, 15.0% difibril, 17.5% trifibril, 12.5% quadrifibril spindles.
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  • 45
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    Journal of Morphology 192 (1987) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 46
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    Journal of Morphology 191 (1987), S. 265-288 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each of the paired salivary glands of third instar larvae of the humpbacked fly Megaselia scalaris is a bag-like structure with a short neck region from which a single duct emerges. The two ducts form a common duct that empties into the ventral region of the pharynx near the mouthparts. The wall of the glands and ducts consists of a simple squamous epithelium that rests upon a connective tissue layer. Cells in the neck are less flattened than those found elsewhere. The basal surfaces of the cells are infolded most deeply in the neck and the least in the duct. The apical surfaces of the cells possess microvilli except in the duct where the apices of the cells are covered by a complex extracellular layer. This layer displays circularly arranged folds that accommodate a thread-like supportive structure resembling taenidial threads of tracheae. Elaborate junctional complexes are associated with the lateral surfaces of the cells. Elements of these complexes include a zonula adherens, a series of pleated septate desmosomes, and conventional desmosomes. The cytoplasm of the glandular cells is filled with RER and other organelles normally seen in cells that export proteins and mucosubstances. Secretory material found in the lumens of the glands reacts only moderately with the PAS procedure but more strongly with alcian blue and methods that demonstrate proteins. The nuclei of the glandular cells contain single large nucleoli and polytene chromosomes whose banding is rather indistinct. Treatment with EDTA produces detrimental effects on all of the foregoing ultrastructural features of the glands and ducts.
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  • 47
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    Journal of Morphology 192 (1987), S. 27-42 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fate and possible roles of the cytoskeleton in the process of conjugation in the hyptrich ciliate Euplotes aediculatus were investigated. Following the coalescence of the plasma membranes of the conjugant cells, a fusion zone or bridge of cytoplasm contributed by both partners is constructed. The sub-alveolar microtubule layers of the vegetative cell cortex remain in place to define the fusion zone boundaries after cell union. The initial fusion zone consists primarily of featureless ground cytoplasm; soon the ground plasm becomes crowded with microtubules and anastomosing smooth endoplasmic reticulum, which become displaced only late in conjugation as the migratory pronuclei are exchanged between partners. Fusion zone microtubules, functioning in some undetermined way, may be involved in the nuclear migration. Resorption of the posterior portion of each partner's buccal apparatus results in the degradation of the component cilia within acid phosphatase-positive autophagic bodies. Silver staining for light microscopy shows that the late fusion zone contracts forward from the posterior border, then constricts to separate the conjugants. In some separating pairs remnants of a microfilamentous assembly are seen at the posterior edge of the fusion zone; the full extent of this system may be masked by partial degradation due to osmium tetroxide fixation. Treatment of conjugants for 6 hours with cytochalasin B prevents separation, possibly through inhibition of the actin-like microfilament assembly in the fusion zone. The observations and experiments favor a model of cell separation following conjugation in which the fusion zone is resorbed by motile or contractile processes occurring within or around the fusion bridge itself.
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  • 48
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    Journal of Morphology 192 (1987), S. 101-111 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the tentacle, a chemosensory and perhaps tactile structure unique among vertebrates to gymnophione amphibians is described in Dermophis mexicanus and Gymnopis multiplicata. The tentacle is associated with the vomeronasal organ and its glands, and utilizes several structures usually associated with the eye, such as the Harderian gland, the retractor and levator muscles, and their nerves. Innervation of the tentacle itself is from the trigeminal nerve. We present an hypothesis that the tentacle originated from modified eye components.
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  • 49
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    Journal of Morphology 192 (1987), S. 145-159 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two types of calcareous spicules occur abundantly in Herdmania momus, a solitary pyurid ascidian with a worldwide warm water distribution. The large spindle-shaped body spicules are 1.5-2.5-mm long and are located primarily in the mantle, siphons, and branchial basket. Each body spicule possesses 100 or more rows of overlapping, unidirectional fringing spines. Numerous body spicules occur regularly spaced within a long common sheath of complex structure, and there are many sheaths per animal. Between neighboring body spicules and overlying the fringing spines are the tightly connected pseudopodial sclerocytes. Spine formation is hypothesized to occur within these cells. The body spicules apparently continue to increase in size throughout the animal's life.The tunic spicules are about one tenth the length of the body spicules. They have 20-40 rows of unidirectional nonoverlapping fringing spines and a mace-shaped spiny base that anchors them at the tunic surface. They form quickly in individual spicular envelopes inside the tunic blood vessels over a 4-5-day period. Each tunic spicule then leaves its surrounding envelope and blood vessel, passes into the tunic, and ultimately protrudes through the outer surface of the tunic. An organic covering inside the envelope closely adheres to the tunic spicules and stains with toluidine blue. Dissolution of the CaCO3 mineral phase by EDTA or EDTA-cetylpyridinium chloride-formaldehyde reveals an intricately patterned organic matrix within or upon which the spicules develop.
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  • 50
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    Journal of Morphology 192 (1987), S. 161-179 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In all species of phylactolaemates, an individual successively produces daughter buds. Individual daughters are designated, according to the order of appearance, as first bud, second bud, and so on. The first bud appears precociously, while the mother is a pear-shaped vesicle. The idea of regarding a main bud, a duplicate bud, and an adventitious bud as a set is not tenable. In the budding region, the cystidal wall shows a constant wavy movement. In Plumatella colonies, branching occurs only when and where a bud of the second or higher order grows up to a zooid. A branch is composed of longitudinally arranged first zooids with the only exception being the most proximal one. The proportion of first zooids in a colony increases in the order of P. casmiana, P. emarginata, and P. repens. The frequency of branching, therefore, decreases in this order. The ancestrula germinated from the statoblast shows the highest activity of budding. The tendency that successively produced daughters of the ancestrula grow in alternate directions is most conspicuous in P. emarginata and least conspicuous in P. casmiana. Replacement budding occurs in these three species of Plumatella, but only under unfavorable culture conditions. The colony of Gelatinella toanensis is characterized by composite branches, each consisting of an axial branch composed of a series of first zooids and of stunted lateral branchlets. In Hyalinella punctata, multiple budding does not necessarily result in branching; zooids of different budding orders coexist in a branch. The genus Pectinatella comprises two species, P. gelatinosa and P. magnifica. Both produce massive colonies. In P. gelatinosa, the colony proper is sac-like with the convex basal wall, and the polypides can retract with the digestive tracts straight. Each individual (except the ancestrula) of this species produces a pair of daughter buds which are located bilaterally relative to the median sagittal plane of the mother. A left bud produces its first bud to the right, and vice versa. In P. magnifica, the colony proper is very thin and flat. When polypides are retracted, the digestive tracts are folded characteristically. Based on these and other results, phylogenetic relationships among the phylactolaemates are discussed.
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  • 51
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The gonads from three hermaphrodite species of different invertebrate phyla were studied at the ultastructure level. In the flatworm Dugesia biblica, male germ cells in different stages of development lay in the lumen of testicular follicles surrounded by overlapping parietal cells. The intercellular space formed by cytoplasmic extensions running parallel to the testis wall is occluded by septate junctions and by an electron-dense material. In the leech Placobdella costata, the testis is lined by a unicellular layer of parietal cells surrounded by densely packed connective tissue fibers. No specialized occluding junctions were found between the parietal cells; however, plasmalemma thickenings and electron-dense material in the intercellular space near to the testis lumen were observed. In the lumen, germ cells develop connected to cytoplasmic masses, the cytophore. In the land snail Levantina hierosolyma, male and female germ cells are found together in the same acini; each acinus is surrounded by a thick basement membrane. At the periphery of the acinus is the ovarian layer; centrally to it is the testicular layer. Intercalated between them is a double cellular layer of follicular cells and of Sertoli cells. The inter-Sertoli space is characterized by elaborate septate junctions. In the three species studied male germ cells develop within the lumina of compartments isolated from the somatic tissue. This separation is brought about by specialized septate junctions, and/or by electron-dense material between the cells that form the testis walls, and also by densely packed connective tissue fibers. Our observations strengthen the view that a male germ cell-somatic tissue barrier as described in the literature of the testes of vertebrates and of invertebrates from various phyla is of general occurrence in the animal kingdom.
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  • 52
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    Journal of Morphology 192 (1987), S. 269-277 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Oocytes from the land hermit crab, Coenobita clypeatus, in various stages of vitellogenesis were examined by light and electron microscopy. Early vitellogenic oocytes are characterized by accumulations of discrete vesicles of endoplasmic reticulum in the perinuclear cytoplasm. As oocytes develop, the endoplasmic reticulum becomes abundant, and numerous Golgi complexes are seen. There is a well developed Golgi-endoplasmic reticulum interaction. Within the confines of the reticulum are discrete intracisternal granules, which can be seen coalescing into electron-dense yolk bodies. Lipid accumulation is seen throughout the cytoplasm. Coincident with the burst of intra-oocytic metabolism are oolemma modifications and micropinocytosis, which provide ultrastructural evidence for extra-oocytic yolk production. The mature oocyte contains numerous yolk and lipid vesicles of varying electron density that comprise both intra- and extra-oocytic substrates.
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  • 53
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    Journal of Morphology 193 (1987) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 54
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    Journal of Morphology 191 (1987), S. 295-308 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histochemistry and ultrastructure (SEM and TEM) of the spermatheca of Biomphalaria glabrata was investigated to elucidate the function of this organ and to compare its structure and function to similar organs found in other species. The spermatheca has a debris-filled lumen surrounded by a thin wall of tissue. The cells adjacent to the lumen are of three columnar epithelial cell types. Two cell types have abundant microvilli and mammalian cell-like organelle distribution and morphology. The above cell types differ in the electron density of their cytoplasms, nuclear morphologies, and organelle content. The third cell type differs from the other two in its cytoplasmic makeup. However, the most distinctive difference is the presence of large numbers of cilia at the apical surface with no evidence of microvilli. These columnar cells rest on a basal lamina adjacent to a two to three cell thick muscle layer. The entire organ is surrounded by an adventitia of unusual morphology. Histochemical investigation demonstrated that DNAase, RNAase, and protease are present in the lumen, alkaline phosphatase is associated primarily with the microvilli, small amounts of acid phosphatase are concentrated in the midcell area of the columnar epithelium, and ATPase activity is localized in the muscle cells and just below the absorptive surface of the microvillous cells. The luminal contents and adventitial areas are Sudan Black B positive, all areas of the lumen and organ wall are PAS positive, the cell nuclei and amorphous masses in the lumen showed Feulgen staining, and large vesicles in the columnar cells were Oil Red O positive. Apparently, the spermatheca of B. glabrata is both a digestive and absorptive structure. Although this organ shares functional similarities with those found in opisthobranchs and terrestrial pulmonates, the epithelia of the spermatheca differ dramatically in these groups.
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  • 55
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    Journal of Morphology 192 (1987) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 56
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    Journal of Morphology 192 (1987), S. 113-123 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In an attempt to investigate the relationships between allometry and locomotory adaptations, we studied the long limb bones of 45 species of insectivores and rodents. Animals ranged from a few grams to about 50 kilograms. Diameter and length of the bones and body mass (when known) were recorded. Regressions of diameter to length, diameter to body mass, and length to body mass were calculated by the least-squares and Model II, or major axis, methods.The results obtained do not agree with the predictions of either the theory of geometric similarity or the theory of elastic similarity. The discrepancies could be due to the fact that animals studied exhibit various modes of locomotion. Moreover, the allometric relationships of the different locomotor patterns are better reflected in insectivores and rodents than in other groups of mammals. The use of a single regression analysis seems to be inadequate when the sample includes a large range of body sizes.
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  • 57
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    Journal of Morphology 192 (1987), S. 181-187 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sensilla that line the upper edge of the lip in the leech Hirudo medicinalis and that contain chemoreceptors required for feeding were examined in the scanning and transmission electron microscopes. The sensilla include two size-classes of ciliated button-like mounds - one about 35 μm in diameter and another about 10 μm in diameter. The larger sensilla are at the center of unpigmented patches of skin which are visible in the light microscope, while the smaller sensilla have not been previously described as distinct structures. Electron microscopy, though not light microscopy, shows that the lip sensilla differ markedly from the segmental sensilla of the leech, which have been shown to mediate mechanoreception and photoreception. In particular, the chemosensory lip sensilla contain multiciliated cells with cilia of a uniform length, whereas the segmental sensilla contain uniciliated cells with long, whip-like cilia, as well as multiciliated cells with short, stiff cilia. Thus, the two types of sensilla differ morphologically as well as functionally. In addition to the ciliated sensilla along the upper lip, structures consisting of a short, club-like process surrounded by granular material were observed inside the mouth. These structures may also be chemosensory organs.
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  • 58
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    Journal of Morphology 192 (1987), S. 193-204 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The architecture and fine structure of the epigastric hematopoietic nodules of the ridgeback prawn, Sicyonia ingentis, are described. The nodules consist of a highly branched series of tubules that contain the maturing hemocytes within a connective tissue stroma. Hemocytes can exit the hematopoietic nodules by penetrating through fenestrations in the endothelial cell layer into the central hemal space or by migrating through the outer later of capsular cells and associated collagen fibrils. Four hemocyte categories were observed: agranular, small granule with cytoplasmic deposits, small granule without cytoplasmic deposits, and large granule hemocytes. This classification was based upon the presence, size, and type of cytoplasmic granules and the presence of cytoplasmic deposits. Only agranular cells and small granule hemocytes without cytoplasmic deposits appeared capable of division. Intermediate stages were observed between agranular hemocytes and small granule hemocytes with deposits and between small granule hemocytes without deposits and large granule hemocytes, suggesting existence of two distinct hemocyte lines.
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  • 59
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    Journal of Morphology 192 (1987), S. 247-256 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This investigation is a light and electron microscopic description of the submandibular duct salivary bladder of the rat, a dilation of the distal end of the main excretory duct. The wall of the bladder consists of (1) a mucosa with pseudostratified epithelium, (2) a submucosal layer of connective tissue, and (3) an underlying layer of striated muscle. The pseudostratified columnar epithelium lining the bladder is composed of three cell types: (1) light cells, (2) dark cells, and (3) basal cells. The lamina propria contains bundles of collagen, attenuated fibrocytes, capillaries with fenestrated endothelia, and nerve fibers which enter the epithelial layer. The capillaries of the submucosa are not fenestrated. The morphology of the wall of this structure provides evidence that the primary fluid of the submandibular gland is modified in the bladder by transepithelial fluid and ion transport.
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  • 60
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    Journal of Morphology 192 (1987), S. 257-268 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The innervation and structure of the lung of the Australian snake-necked tortoise, Chelodina longicollis, was examined by using light microscopy including fluorescence histochemical techniques. The anterior lung was divided into a number of compartments with numerous alveolar spaces. The posterior lung was simpler and saclike in structure and alveolar spaces were absent. Smooth muscle fibers occurred in discrete muscle bands and in the walls of the septal bands. Ganglion cells occurred along nerve trunks throughout the lung but were more numerous in the posterior lung. Smooth muscle bands, the extrinsic pulmonary artery, and the arteries within the lung were sparsely innervated by adrenergic fibers. Substance P-containing sensory fibers were not demonstrated. The innervation and structure of the lung are compared to published work on other reptiles.
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  • 61
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    Journal of Morphology 193 (1987), S. 13-22 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastuctural changes in the intestinal connective tissue of Xenopus laevis during metamorphosis have been studied. Throughout the larval period to stage 60, the connective tissue consists of a few immature fibroblasts surrounded by a sparse extracellular matrix: few collagen fibrils are visible except close to the thin basal lamina. At the beginning of the transition from larval to adult epithelial form around stage 60, extensive changes are observed in connective tissue. The cells become more numerous and different types appear as the collagen fibrils increase in number and density. Through gaps in the thickened and extensively folded basal lamina, frequent contacts between epithelial and connective tissue cells are established. Thereafter, with the progression of fold formation, the connective tissue cells become oriented according to their position relative to the fold structure. The basal lamina beneath the adult epithelium becomes thin after stage 62, while that beneath the larval epithelium remains thick. Upon the completion of metamorphosis, the connective tissue consists mainly of typical fibroblasts with definite orientation and numerous collagen fibrils. These observations indicate that developmental changes in the connective tissue, especially in the region close to the epithelium, are closely related spatiotemporarily to the transition from the larval to the adult epithelial form. This suggests that tissue interactions between the connective tissue and the epithelium play important roles in controlling the epithelial degeneration, proliferation, and differentiation during metamorphic climax.
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  • 62
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    Journal of Morphology 193 (1987), S. 91-98 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gene's organ of the camel tick Hyalomma (Hyalomma) dromedarii is located in the anterodorsal region of the body cavity ventrad to the scutum. It consists of a short stalk, dividing posteriorly into 2 pairs of horns and then into tubular glands. In unfed ticks, the eipithelial layer of both the stalk and horns is lined internally by 2 cuticular layers; an inner, thin, greatly folded, dense layer surrounds the organ main lumen, and an outer, thick, slightly folded, less dense layer abuts the cell apices. Only the inner cuticular layer extends into the horn posterior region and appears perforated with numerous pore canals and covered with fine, cuticular projections. The horn and tubular glands epithelium is structurally consistent with a secretory function that apparently increases as feeding progresses. During oviposition, the inner cuticular layer unfolds and inflates into a pair of balloonlike structures that evert through the organ external aperture to receive and manipulate each egg as it is laid, coating it with a waxy layer that prevents desiccation. The fine cuticular projections may have a function in gripping the eggs as they leave the vagina. This organ appears to be everted by hydrostatic pressure from the hemolymph and is retracted by muscles.
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  • 63
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    Journal of Morphology 193 (1987), S. 135-158 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The identification, spatial relationships, and sequences of development of the cartilaginous and bony elements of the chondrocranium, osteocranium, and splanchnocranium in the medaka, Oryzias latipes, are described here for the first time. The development of the cartilaginous head skeleton commences at stage 29 and is essentially complete by stage 35 (hatching). The parasphenoid bone and two pairs of branchiostegals are present at this stage and several other replacement and dermal bones begin to appear shortly thereafter. Development of the osteocranium and ossification of the splanchnocranium continue throughout the larval and juvenile phases and are essentially complete at sexual maturity at approximately 3 months (at 25°C), at which time the fish range in length between 25 and 30 mm.The description of the adult head skeleton of O. latipes is compared to those of O. melastigma, O. luzonesis, and other Oryzias spp. previously described and a redesignation of the relationships between certain elements in the adult head skeleton is proposed, based on the developmental data presented. Furthermore, the value of the medaka as a model teleost to study the embryological origins of, and in particular, the neural crest contributions to, the cranial and visceral skeleton is outlined based on certain characteristics of the medaka's life history traits. These include the ease of obtaining embryos for which the exact time of fertilization is known (without sacrificing any brood stock) and the relatively rapid development of the chondrocranium, which is nearly complete at hatching, a process which can occur in as short a time as 6 days (at 34°C). The usefulness of the ontogenetic data obtainable from further studies into the embryonic origins of head and visceral skeletal elements revealed in the present study, is briefly discussed.
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  • 64
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    Journal of Morphology 193 (1987), S. 217-224 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Puerto Rican tree frog, Eleutherodactylus coqui, has internal fertilization and direct development on land. In light of these reproductive adaptations, the events of fertilization and early development were studied. Cytological examination of just-fertilized eggs showed that sperm entry is restricted to about 10% of the surface of these large, yolky eggs, and all nuclear events of the first cell cycle occur near the animal pole. Although the oocytes have cortical granules, a number of polyspermic fertilizations were found. One clutch consisted of eggs with a high frequency of polyspermy and of normal development. This raises the possibility that normal development can occur despite multiple sperm entry, a situation not found in other anuran amphibians. With respect to saline requirements, the sperm and the embryo are similar to those in amphibians with external fertilization and aqueous development. Sperm motility was high in low-tonicity conditions, and the normally terrestrial embryo could develop completely from a fertilized egg to a froglet in a low-tonicity aqueous solution.
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  • 65
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    Journal of Morphology 193 (1987), S. 197-216 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The present study examined the time sequence of degeneration and regeneration after transection of the eighth nerve in the red-eared turtle as well as the chromatolytic reaction of the turtle auditory ganglion cells. Horseradish peroxidase (HRP) transport between auditory ganglion cells and the medulla identified eighth nerve connections. The course of eighth nerve degeneration was followed with Fink and Heimer degeneration stain and HRP reaction. Cresyl-violet-stained sections through auditory ganglion cells were observed for chromatolysis.Degeneration by-product was intense in the eighth nerve and primary auditory nuclei in turtles surviving 25 and 32 days after eighth nerve transection. Turtles surviving 45 days or less after eighth nerve transection showed HRP reaction product in the eighth nerve to the point of its dorsolateral penetration into the medulla following cochlear duct injections. Acoustic tubercle injections in 50-day survivors showed HRP filling in eighth nerve and auditory ganglion cells. Cochlear duct injections in 67-day survivors demonstrated HRP filling in the eighth nerve and acoustic tubercle. Sections stained for degeneration in 67-day survivors showed little or no degeneration by-product and 80- and 90-day survivors showed none.The proportion of chromatolytic auditory ganglion cells was greatest in the 50-day postoperative turtles when compared to control turtles and other survival stages. Animals which survived longer than 50 days had reduced numbers of chromatolytic cells.Results suggest that the eighth nerve fibers are regenerated to primary brainstem auditory nuclei in experimental turtles surviving 50 days or more. Regeneration occurs between the 45th and 50th day following transection.
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  • 66
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    Journal of Morphology 194 (1987), S. 311-322 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The architecture of follicular blood vessels in the ovary of lizards (Anolis equestris and Anolis carolinensis) was studied by standard histology and also after vascular perfusion with an orange silicone-rubber compound or with India ink. The theca of the follicular wall contains a netlike arrangement of anastomosing sinusoids, which increase in size as a follicle grows. An avascular stigma forms in very small, growing follicles when a portion of the follicular wall contacts the ovarian surface epithelium. Blood vessels then invade the theca except in the zone of contact. The diameter of the stigma is about 50% of follicular diameter, regardless of follicular size. Although the stigma of smaller follicles is avascular, that of vitellogenic follicles is hypovascular, i.e., a few vessels radiate into the stigma region. The antiangiogenic process involved in stigma formation may continue as the stigma enlarges. The development pattern of stigma formation found in Anolis is displayed by many other vertebrates.
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  • 67
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    Journal of Morphology 191 (1987), S. 115-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Generalized anuran tadpoles across families exhibit a similar neuromast morphology on their heads, as follows: (1) all neuromast lines known for anurans are present; (2) within these lines total neuromast number ranges from about 250 to 320; (3) neuromasts form linear stitches composed of two to three, but sometimes up to five, neuromasts; (4) neuromast linear dimensions are ≤ 10 μm; and (5) neuromasts contain ≤ 15 hair cells. Compared with generalized forms, stream, arboreal, carnivorous, and desert-pond forms have fewer neuromasts but they contain more hair cells. They do not, however, form stitches. Obligate midwater suspension-feeding forms, including Xenopus (Pipidae), Rhinophrynus (Rhinophyrnidae), and Phrynomerus (Microhylidae), form stitches that contain 〉 six, but potentially up to 18 or more, loosely aggregated neuromasts. Xenopus and Rhinophrynus have large neuromasts (up to 40 μm across). Chiasmocleis (Microhylidae) tadpoles form stiches that are linearly arranged with up to ten neuromasts. Whereas urodeles can have more than one neuromast row per line and may form both linear and transverse stitches, anurans have only one row of neuromasts per line and form only transverse stitches. Neuromasts in anurans tend to be smaller and more circular than in urodeles and positioned flush with the epidermal surface. A greater percentage of anurans form stitches, and anurans have greater intrafamilial variation in stitch formation than do urodeles.
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  • 68
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    Journal of Morphology 191 (1987), S. 161-175 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy, architecture, and innervation patterns of the hamstring muscles, biceps femoris, and semitendinosus were examined in adult cats using microdissection and glycogen-depletion techniques. The biceps femoris muscle consists of two heads. The anterior head, which attaches mainly to the femur, is divided into two parts by the extramuscular branches of its nerve. The posterior head is innervated by a single nerve. Semitendinosus is composed of two heads, one proximal and one distal to a tendonous inscription, each of which is separately innervated. The extramuscular branches of the nerves to these hamstring muscles thus partition them into innervation subvolumes termed parts. The available evidence suggests that each of the parts of these muscles so innervated is not equivalent to the collections of single motor units that have been described for ankle extensors as neuromuscular compartments. It is quite likely that each of the parts of the hamstring muscles may contain more than one neuromuscular compartment. Using chronically implanted EMG electrodes, the activation patterns of different parts of the hamstring muscles were analyzed during locomotion. The anterior and middle parts of biceps femoris are active during the early stance phase, probably producing hip extensor torque. The posterior part of biceps femoris and semitendinosus act most consistently as flexors, during the early swing phase, but also may function in synergy with hip, knee, and ankle joint extensors near the time of foot placement. Greater variability is found in the activity patterns of posterior biceps femoris and semitendinosus with respect to the kinematics of the step cycle than is observed for anterior and middle biceps femoris. It is suggested that this variation may reflect a larger role of sensory feedback in shaping the timing of activity in posterior biceps femoris and semitendinosus than in ‘monarticular’ muscles.
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  • 69
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    Journal of Morphology 191 (1987), S. 217-224 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The interradicular periodontal ligament of mandibular molars contains an apparently unique dilated vessel straddling the interradicular alveolar bone. This structure is designated a venous ampulla. The vessel possesses a luminal length and width of approximately 200 × 100 μm, respectively. Ultrastructurally, the endothelium has an average thickness of 0.35μm, a continuous basement membrane, and an incomplete layer of pericytes. Open endothelial junctions are not present. The anatomy of the vessel wall differs markedly on the dental- and bone-related aspects. Calculated ratios for the luminal diameter to wall thickness vary from 1:80 to 1:150. Postcapillary-sized limbs from this vessel drain into the interradicular septum of bone and the ligament microvascular bed. Arterial supply to the ampulla is provided via arteriovenous anastomoses characterized by their association with myelinated and unmyelinated nerve groups.Oxytalan fibers are present throughout the wall of the venous ampulla, penetrating to the abluminal side of the endothelium where they are associated with unmyelinated axons and free nerve endings. Elsewhere, oxytalan fibers are related to the arteriovenous anastomoses and their accompanying myelinated and unmyelinated nerves located adjacent to the endothelium. Pericytes form membranous contacts with the endothelium of the arteriovenous anastomoses and have processes penetrating the endothelium basement membrane.
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  • 70
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    Journal of Morphology 191 (1987), S. 289-294 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five morphological categories of hemocyte (prohemocyte, ameboid plasmatocyte, spindle-shaped plasmatocyte, oenocytoid, and granular cell) were observed by light and electron microscopy of hemolymph from Tipula paludosa larvae. In addition, vast numbers of membrane-bounded granule-containing fragments were present, and were also found in the larval hemolymph of four other Tipula spp. The fragments appear to be derived from the granular cells, which readily fragment. Granules in the granular cells and the fragments appear to have similar substructure. Melanization and coagulation of the hemolymph occur rapidly on exposure to air; the granular cell fragments may be concerned with one or both of these processes.
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  • 71
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    Journal of Morphology 192 (1987), S. 1-11 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The middle ears of some species of anurans display a set of features that are derived. Some of these features have obvious adaptive significance, whereas the adaptive significance of other derived features is rather obscure. The sequence of histological differentiation of the elements of the derived anuran middle ear, as well as the pattern of morphological changes in their shape, were analyzed and compared with the morphogenesis of the generalized middle ear. Most of the derived features are paedomorphic characters associated with truncated development. The accelerated rate of the opercular development, together with the delayed initiation of function in the tympanic system, permit heterochronic development phenomena to affect the formation of anuran sound-conducting systems.
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  • 72
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    Journal of Morphology 192 (1987), S. 43-61 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation and subsequent dissolution of a common bridge of cytoplasm between conjugating ciliated protozoan cells provides an excellent opportunity to follow the dynamics of the cellular membrane systems involved in this process. In particular, separation of conjugant partners offers the chance to observe, at a fixed site on the cell surface, how the ciliate surface complex of plasma and alveolar membranes (collectively termed the “pellicle”) is constructed. Consequently, cortical and cellular membranes of Euplotes aediculatus were studied by light and electron microscopy through the conjugation sequence. A conjugant fusion zone of shared cytoplasm elaborates between the partner cells within their respective oral fields (peristomes) to include microtubules, cytosol, and a concentrated endoplasmic reticulum (heavily stained by osmium impregnation techniques) that may also be continuous with cortical ER of each cell. Cortical membranes displacd by fusion are autolyzed in acid phosphatase-positive lysosomes in the fusion zone. As conjugants separate, expansion of the plasma membrane may occur through the fusion of vesicles with the plasma membrane, presumably at bare membrane, presumably at bare membrane patches near the fusion zone. The underlying cortical alveolar membranes and their plate-like contents are reconstructed beneath the plasma membrane, apparently by multiple fusions of dense-cored alveolar precursor vesicles (APVs). These precursor vesicles themselves appear to condense directly from the smooth ER present in the fusion zone. No Golgi apparatus was visible in the fusion zone cytoplasm, and no step of APV maturation that might involve the Golgi complex was noted.
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  • 73
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    Journal of Morphology 192 (1987), S. 63-85 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The differences in angulation and length observed for the fibers of anatomical muscles may reflect two distinct mechanical requirements: (1) arrangement for pinnation, reflecting an increase in physiological crosssection and (2) arrangement for equivalent placement of sarcomeres, possibly associated with coordination. The observed differences in fiber angulation and length have different effects upon the responses of sarcomeres, specifically on their extent and rate of shortening and on the force they may generate. The basic mechanisms governing these effects and the various arrangements of muscles are reviewed. Fiber length and angulation in the complex M. adductor mandibulae externus 2 of a lizard were measured stereotactically; these values correlace well with the hypothesis that the muscle shows equivalence and demonstrate that angulation for pinnation is less constant. An outline for the study of muscle architecture and function, detailing the kinds of information required to estimate forces and evaluate muscle and fiber placements, is presented.
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  • 74
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    Journal of Morphology 192 (1987), S. 125-144 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The progression of ovarian follicular development in the Northern Alligator Lizard has been documented ultrastructurally and by enumeration of cells, with a focus on changes in the granulosa component of the follicle. The pattern of cellular differentiation of the granulosa entails, as in other lizards, the transformation of a simple, cuboidal epithelium in small follicles into a complex layer consisting of three types of cells. Marked differences in size and ultrastructure of the cell types indicate different functional states: the smallest cells are little differentiated and serve primarily as stem cells to other granulosa cells throughout follicular growth, whereas the larger “intermediate” and “pyriform” cells do not divide and show ultrastructural features indicative of synthetic activity. Contrary to some views that this latter cell type is the final step in cellular differentiation and provides organelles and cytoplasm to the oocyte through an intercellular bridge, the results of this study suggest that only relatively small molecules such as ribosomal RNA might pass between cells. Further, these observations support the interpretation that a heterogeneous granulosa results from the fusion in early follicular stages of some cells that are in surface contact with the oocyte. Several of the cytological features of the larger granulosa cell types are seen in the oocyte and in germ-line cells generally, such as highly dispersed chromatin, large nucleoli, abundant nuclear pores, mitochondrial “rosettes,” annulate lamellae, “ribosome bodies,” and surface microvilli. This strongly suggests that the cytology of large granulosa cells is induced by the oocyte. The heterogeneous granulosa persists only through previtellogenesis and at the onset of exogenous yolk uptake by the oocyte it becomes a secondarily homogeneous layer. The appearance of the granulosa at this stage is similar to that of reptiles whose granulosa remains a single-cell layer throughout folliculogenesis (e.g., turtles and crocodilians). Thus, although follicular development has been scrutinized in only a few representative genera of reptiles to date, the course of follicular development among lizards is similar in detail and involves the transitory development of a heterogeneous population of cells. This feature appears to be exclusive to the squamate reptiles.
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  • 75
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    Journal of Morphology 192 (1987) 
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  • 76
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    Journal of Morphology 192 (1987), S. 229-236 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retrograde fluorescent labeling technique reveals that trigeminal projections to the ventroposteromedial nucleus of the thalamus (VPM) of the rat originate from the main sensory nucleus (MSN) of the trigeminal and subnuclei interpolaris (V1) and caudalis (Vc) of the spinal trigeminal nucleus. These projections are predominately contralateral; however, the presence of a few ipsilateral labeled cells in MSN suggests an uncrossed trigeminothalamic pathway. Trigeminocerebellar fibers projecting to the paramedian lobule (PML) of the cerebellar cortex are located in Vi and caudal subnucleus oralis (V0). This is principally an ipsilateral pathway, but several bisbenzimide-labeled cells are present in contralateral Vi. The most notable finding occurred after paired injections of Evans Blue into VPM and bisbenzimide into PML, demonstrating neurons in Vi with divergent projections to both structures. The presence of this type of projection was not found in mice (Steindler: J. Comp. Neurol. 237:155-175, 1985) and has not been reported in other species.
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  • 77
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    Journal of Morphology 193 (1987), S. 1-11 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The bursa copulatrix of the silkmoth is filled with various secretions and seminal fluid transferred from the male reproductive system during mating. The contents of the bursa include a pearly body, spermatophragma, and spermatophore. The latter consists of a four-layered wall, an inner and outer matrix, and a soft plug. The components of the spermatophore are all heterogeneous, since they are formed by the partially mixed, viscous streams of the male secretions. Apyrene spermatozoa and eupyrene bundles are present only in the inner matrix, but both the matrices are important sites of sperm maturation. After spermatophore formation, the basophilic regions and periodic acid-Schiff (PAS)-granules in both matrices gradually decrease with time. The PAS-granules were identified as glycogen by α-amylase treatment. The inner matrix containing sperm and the outer matrix decrease in volume and become concentrated near the neck of the spermatophore. Apyrene and eupyrene spermatozoa can move toward the ductus seminalis after their maturation. A large, beltlike space which does not stain remains at the periphery of the spermatophore. These structural changes of spermatophore contents seem to reflect metabolic reactions in the spermatophore as the reactor for sperm maturation.
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  • 78
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    Journal of Morphology 193 (1987), S. 53-62 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The insect wing is formed from an epithelial sheet that folds during development to establish a saclike tissue with an upper and a lower epithelial monolayer. The adult cuticle formed by the upper and lower monolayers has a distinctive pattern of thickened regions called veins. The venation pattern on the lower surface matches that on the upper surface. As demonstrated by transposition of grafts from the upper monolayer, determination of venation pattern occurs prior to pupation in both wing monolayers. However, the pattern is not expressed until later in adult development. Expression of this determined pattern occurs autonomously in most circumstances. One circumstance in which the pattern fails to be expressed is in pieces of the upper monolayer that are isolated from the lower monolayer before adult cuticle deposition and expression of venation pattern. The only evident interaction between the two monolayers of the wing occurs during a 3-day period, 6-8 days after pupation. During this time, the basal laminae segregating upper monolayer from lower monolayer disappear, and the basal ends of cells form desmosomal junctions at the interface between upper and lower monolayer. Transposition as well as isolation of tissue fragments from the upper monolayer suggest that this interaction between the basal surfaces of the two monolayers is a prerequisite for evocation of venation pattern.
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  • 79
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    Journal of Morphology 193 (1987) 
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  • 80
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    Journal of Morphology 193 (1987), S. 159-171 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: On the antennal tip of Eurypauropus ornatus are 3 threadlike sensilla - the flagella, and a single spheroid sensillum - the globulus. Each of the 3 flagella is innervated by 2 groups of sensory cells. One group contains 4 cells, the other, 5. All cells of the “four group” and 3 of the “five group” are comprised of single cilia and unbranched dendrites which extend along the lumen of the flagellum. Two cells of the “five group” have double cilia and pairs of unbranched dendrites. One pair also enters the flagellum and the other pair terminates beneath the flagellar base to form a concentric array of lamellae. No pores are present in the cuticular wall.Eight sensory cells innervate the globulus. They are arranged in 3 groups, one triplet and 2 pairs, in addition to a single cell. The single cell contains a pair of cilia whose unbranched dendrites differentiate into tubular bodies that are inserted into the base of the globulus. Each of the other 7 sensory cells has a single cilium. Their unbranched dendrites penetrate into the globulus in 3 groups as described for the sensory cells. The dendrites in each group terminate in an individual pore channel at the globulus tip and completely fuse with the electron-dense material that plugs the pore channel.Based on structural similarities to sensilla having known functions, it is probable that the flagella and the globulus are chemoreceptors, the former responding to odors, the latter sensitive to substances in aqueous solution.
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  • 81
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    Journal of Morphology 193 (1987) 
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  • 82
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    Journal of Morphology 194 (1987), S. 219-220 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 83
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    Journal of Morphology 193 (1987), S. 173-184 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive organs possibly involved in food absorption in Loligo vulgaris and L. forbesi are the caecum, the intestine, the digestive gland, and the digestive duct appendages. The histology and the fine structure showed that the ciliated organ, the caecal sac, and the intestine are lined with a ciliated epithelium. The ciliary rootlets are particularly well developed in the ciliated organ, apparently in relation to its function of particle collection. Mucous cells are present in the ciliated organ and the intestine. Histologically, the digestive gland appears rather different from that of other cephalopods. However, the fine structure of individual types of squid digestive cell is actually similar to that of comparable organs in other species, and the squid cells undergo the same stages of activity. Digestive cells have a brush border of microvilli, and numerous vacuoles, which sometimes contain “brown bodies.” However, no “boules” (conspicuous protein inclusions of digestive cells in other species) could be identified in their cytoplasm; instead only secretory granules are present. In the digestive duct appendages, numerous membrane infoldings associated with mitochondria are characteristic features of the epithelial cells in all cephalopods. Two unusual features were observed in Loligo: first, the large size of the lipid inclusions in the digestive gland, in the caecal sac, and in the digestive duct appendages; and second, the large number of conspicuous mitochondria with well-developed tubular cristae. When injected into the caecal sac, ferritin molecules can reach the digestive gland and the digestive duct appendages via the digestive ducts, and they are taken up by endocytosis in the digestive cells. Thus, it appears that the digestive gland of Loligo can act as an absorptive organ as it does in other cephalopods.
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  • 84
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    Journal of Morphology 193 (1987), S. 263-276 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mode of sexual reproduction and embryogenesis was compared in 3 species of Botrylloides: B. simodensis, B. lenis, and B. violaceus. In all species, a testis and an egg (occasionally 2 eggs), the former being anterior to the latter, mature in the mantle on either side of a zooid. The egg is surrounded by 2 follicular layers and is attached by a vesicular follicle stalk (oviduct) to the atrial brood pouch. The egg is ovulated into the brood pouch, where it is fertilized and undergoes embryogenesis. The egg of B. simodensis is heavily yolked and measures about 180 μm in diameter. The course of embryogenesis in this species is that typical of ascidians. A mature tadpole larva is produced and shed in about 5 days; then, the mother zooid degenerates. The larva is smallest of the three species and has 8 ampullae. The metamorphosed oozooid bears a single bud on the right side only. Extraembryonic nutrition seems to be very limited.Both Botrylloides lenis and B. violaceus are species which display extreme examples of viviparity. Their eggs are devoid of yolk granules, measuring about 90 μm in diameter in the former species and 60 μm in the latter. The course of embryogenesis is similar in these 2 species. The neurula stage is characterized by a spherical vesicular shape owing to precocious differentiation of the embryonic pharynx, whose ectoderm becomes vacuolated. At the posterior end of the neurula, the mesodermal cells are located in a mass, from which the tail is extended later. In B. lenis, embryogenesis takes about 20 days. At the neurula stage of the embryo, the mother zooid becomes a mantle sac as a result of visceral disintegration. During further embryogenesis, the growth of buds of successive generations in the colony is characteristically arrested. A swimming larva of this species is somewhat larger than that of B. simodensis. It has 14-24 ampullae, and the oozooid carries a single bud on its right side. In B. violaceus, the gestation period lasts for more than a month. At the early gastrula stage of the embryo, the body of the mother zooid fully disintegrates. Only the brood pouch bearing the embryo survives and remains connected with the colonial vascular system. In this species, sexual reproduction does not affect the growth of buds in the colony. The swimming larva is gigantic, being furnished with 24-34 ampullae, and the oozooid always bears 3 buds, 2 on the right side and one on the left side.
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    Journal of Morphology 194 (1987), S. 55-64 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In lacertids the telencephalic vesicle starts its development at stage E = 30, at which time it is lined by a homogeneous nucleated zone in which particular ventricular zone territories or sulci cannot be distinguished. At stage E = 32 coinciding with the initial development of the anterior dorsal ventricular ridge (ADVR), one may distinguish the ventricular zone b in the dorsolateral wall of the ventricle adjacent to the sulcus lateralis. The ADVR continues growing by incorporation of cells produced in two proliferative zones (zone b and wall of the sulcus lateralis) and appears fully developed in postnatal lizards. Ultrastructural characteristics of young ADVR neurons between stages E-32 and E-33 are typical of those in immature cells. Beginning at stage E-34, some of these neurons appear to be degenerating (pycnotic). Thereafter, neurons of the ADVR develop abundant cytoplasmic organelles and the neuropile grows quickly. Myelination starts in the ADVR between stages E-38 and E-40, but is not observed in other striatal masses in the same period. Vascularization begins and is well developed at E-40. The first synaptic contacts were observed in embryos of stage E=38; they are chiefly axo-dendritic, although some are axo-somatic. Degenerating neurons were found in the ADVR up to hatching. From stage E-40 onward, the ADVR shows a greater and more rapid differentiation than all other striatal nuclei, including the ventral and amygdaloid complex.
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  • 86
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    Journal of Morphology 194 (1987), S. 85-109 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Suction feeding in Astatotilapia elegans occurs by a series of rapid, coupled movements of various head parts. The lower jaw rotates with respect to the neurocranium through an angle of 62° in less than 15 ms. The power requirements for jaw depression are calculated from a mathematical model and may reach a peak of ±4 watt in a 12-cm-long specimen. Data from the literature on mechanical output of fish muscle suggest that a muscular volume equal to 44% of the volume of the fish (= 45 cm3) should be required, if it is premised that movement and muscle shortening are directly coupled. Therefore, we assumed that storage and release of strain energy must be considered. The work demands for depression equal 0.014 J. The amount of energy storable in only three pairs of head ligaments can be estimated between 0.008 J and 0.05 J. The use of strain energy implies initial blocking and subsequent triggering of the movement. The position of the hyalomandibular connection, dorsal to the mandibular-suspensorial articulation, appears to be of crucial importance in balancing the forces of sternohyoideus and the body muscles. Triggering at the onset of jaw depression occurs by the contraction of the levator operculi. The line of action of the hyalomandibular connection is lowered beneath the jaw suspension, which raises the equilibrium of forces. Elastic recoil can occur thereafter.
    Additional Material: 10 Ill.
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  • 87
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rostral end of the forebrain was classically defined on the basis of descriptive data. Different assumptions on the mode of closure of the rostral neuropore caused three different theories of the rostral end of the forebrain to be formulated (His 1893a; von Kupffer, '06; Johnston, '09). Some recent descriptive and experimental data have put these theories into question.A piece of black nylon thread was inserted through the rostral neuropore of chick embryos and was fixed to its ventral lip. These operations were done at all intermediate stages during the process of closure of the rostral neuropore. The embryos were sacrificed at a later stage, by which time the neuropore had disappeared.In the cleared specimens the threads always lay at the same site, namely the upper border of lamina terminalis, irrespective of the stage at which the marker was inserted. These results stand against His's conception ((1893a, b) of a sutura terminalis and support the single mechanism of sutura dorsalis during closure of the rostral neuropore. The marking data therefore imply that the topologic rostral end of the forebrain lies at the upper limit of lamina terminalis, as proposed by von Kupffer, '06).
    Additional Material: 7 Ill.
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  • 88
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    Journal of Morphology 194 (1987), S. 209-217 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The glycogen body is a functionally enigmatic structure located in lumbosacral region of the spinal cord in birds. This tissue is unique to birds, and, although it is believed to be present in all species, studies on the glycogen body to date have been confined largely to the domestic chicken. The present study is the first to describe the glycogen body of the Japanese quail (Coturnix japonica) during incubation and at hatching. Light microscopy and histochemistry were used to identify the glycogen body in the spinal cord of the developing quail beginning at 7 days of incubation and to ascertain the presence of nerve fibers in that tissue at hatching.
    Additional Material: 6 Ill.
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  • 89
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    Journal of Morphology 194 (1987), S. 235-245 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nerve pathways in the praesoma, based on light microscopy of serial transverse, sagittal, and longitudinal sections stained with Ehrlich's acid hematoxylin are described for the first time for a memeber of Neoechinorhynchus. The route from the cerebral ganglion to the musculature and sense organs of the proboscis and body wall for 11 nerves, five pair and one single, the presence and structure of the Stutzzelle (support cell) and its association with the neck sense organs are described. A comparison with the nervous system in the praesoma of Paulisentis fractus is discussed.
    Additional Material: 19 Ill.
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  • 90
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 194 (1987), S. 247-263 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Study of the oviduct of the pied myna (Sturnus contra contra) throughout the year reveals that oviducal weight, length, surface epithelial height and glycogen content are low during August to January (nonbreeding phase), partially increase during February to April (prebreeding phase), maximally increase in May (breeding phase) and decrease in June and July (post-breeding phase). In the nesting cycle, there is greatest growth in all the regions of the oviduct from early nest-building to the egg-laying period and this is followed by rapid involution during incubation and nestling periods.Some notable features in the oviduct of the pied myna are described: (1) All five regions of the oviduct (infundibulum, magnum, isthmus, uterus, and vagina) are clearly distinguishable when studied from serial sections of the oviduct even during the nonbreeding phase of the annual ovarian cycle. (2) There is a strong correlation between initiation of tubular gland formation and the onset of nestbuilding activity. (3) The distal part of the magnum is differentiated into a ‘mucous region’ having well developed basal nonciliated cells. (4) A sixth zone can be identified between the magnum and isthmus. Sperm hostlike glands exist at the cranial end of the zone. (5) Several circular epithelial invaginations are evident in the intermucosal folds and their size decreases in centripetal order in the vagina. (6) The pattern and degree of regression are different in various regions of the oviduct.A close synchrony between ovarian and oviducal cycles is indicated in the pied myna (Sturnus contra contra).
    Additional Material: 22 Ill.
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  • 91
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 194 (1987), S. 265-274 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dorsal cortex of Psammodromus algirus is three-layered. From the pia to the ependyma, it consists of a superficial plexiform layer, a cellular layer, and a deep plexiform layer. Five neuronal types have been classified in the dorsal cortex. Pyramidal neurons represent 18.75% of neurons and differ morphologically depending on their position in the pars medialis or lateralis of dorsal cortex. Pyramidal neurons in the pars medialis are smaller and their apical dendritic fields are less extensive than those of pyramidal neurons in the pars lateralis. Bitufted neurons represent 22.5% of dorsal cortical neurons and are only found in the cellular layer of the pars lateralis. Multipolar neurons are distributed in the pars medialis and lateralis, in the cellular layer and the deep plexiform layer; they represent 46.25% of the total impregnated cells. Bipolar neurons are found mainly in the deep plexiform layer and form 11.25% of neurons. Two subtypes may be distinguished: horizontal and vertical bipolar cells. Juxtaependymal neurons represnt 1.25% and are located just above the ependyma. All the neurons in the cellular layer are projection cells.
    Additional Material: 12 Ill.
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  • 92
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 194 (1987), S. 323-348 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the saccule of the inner ear in the toadfish was studied using light and scanning electron microscopy. Development was studied from the early embryo (2-3 days postfertilization), when the otocyst first forms, to the early-aged juvenile when the development of the inner ear approximates that of the adult (4 weeks postfertilization). The ultrastructural features examined included the morphological sequence of ciliary bundle growth, the development of orientation patterns of the ciliary bundles, and the relation of the ultrastructural development to overall gross development.Gross development may be divided into four distinct morphological stages. Stage I encompasses the time from initial formation of the otocyst until the start of stage II, which is the stage when the pars inferior begins migrating ventrally. In stage III the pars inferior continues to elongate ventrally. Stage IV starts when the pars inferior elongates in a rostral and caudal direction. The ear attains its adult shape in stage IV.The differentiation of the sensory cells begins during stage I. During the early part of stage I, a small cilium is found on the apical surface of each cell throughout the otocyst. In the middle and late periods of stage I, a few micro - villous buds add to the surface of the cells that already have a kinocilium. These early ciliary bundles are clustered on the rostral - ventral and caudal walls of the otocyst. There is no clear patterning to the orientation of these ciliary bundles. In stage II the ventral stretching of the labyrinth wall causes a spreading of the clustered bundles along the ventral and medial walls of the pars inferior. The orientation of the ciliary bundles has no distinct pattern. In stage III the orientations of the ciliary bundles appear adultlike, although there are so few ciliary bundles that it is difficult to make a definite determination. During stage IV, hair cells with an adultlike horizontal and vertical orientation pattern are found on the rostral and caudal sections of the saccular macula, respectively. The transition region lying between these areas has ciliary bundles with various orientations.
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  • 93
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    Journal of Morphology 193 (1987), S. 253-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Among vertebrates, some teleosts are unique in having bone which lacks osteocytes embedded in the matrix. The fate of cells that secrete the matrix of these acellular bones has not been investigated thoroughly. Histological and fluorescent microscopic analysis of the vertebral bone of Oryzias latipes demonstrated that acellularity is not a secondary appearance of an early cellular bone during ontogeny. Vertebral bone is devoid of cells embedded in the matrix throughout development. Cells that secrete bone matrix do not become trapped in their own secretion. Instead, they always remain as a surface layer over the outer surface of the bone. Fluorescent microscopic visualization of tetracycline injected into growing fish demonstrated that bone was only deposited by osteoblasts lining the outer surface of the bone; no deposition of bone took place on the inner surface.
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  • 94
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    Journal of Morphology 193 (1987), S. 305-315 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the Ceratitis capitata embryo, furrow formation follows the last mitosis divisions and leads to cellular blastoderm formation. This process displays several interesting features and requires the participation of bundles of microfilaments which are located at the furrow base at the onset of cytokinesis and contract synchronously, determining furrow growth. The new membranes for furrow growth seem to be largely provided by the fusion of many vesicles. Surface projections do not appear to contribute significantly to this phenomenon. At the end of cytokinesis the microfilaments are sandwiched between the plasma membrane and cisternae of endoplasmic reticulum. Subsequently the microfilaments disappear from the cytoplasmic side of the membrane but remain beneath the membranes of the connections and at the periphery of the yolk sack until gastrulation. On the basis of these observations some ultrastructural aspects of furrow formation and the role that the microfilaments may play during this process are discussed.
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  • 95
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    Journal of Morphology 193 (1987), S. 277-284 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the paired foveae dorsales and foveal glands in the unfed female Amblyomma americanum is described and compared with that in other tick species. Each fovea opens to the exterior via pores which lead internally into a single cuticular tube, the pore-tube. This is surrounded by 2-3 epithelial cells. The pore-tube enlarges basally forming a large cavity possessing a cup-shaped cytoplasmic protrusion. The pore-tube cuticular lining extends downward to form an electron-dense, flaplike protrusion bracketing narrow cytoplasmic extensions filled with microtubules. These extensions form a previously undescribed valvelike structure that seems to control the flow of pheromone secretion from the foveal gland to the pore-tube.The single foveal gland lying beneath each pore-tube is composed of 2-3 inner, large, storage cells surrounded by outer, spindle-shaped cells; both types of cells have a characteristic feature of epithelia involved in secretory activity and ion transport. The outer cells extend upward to join the base of the poretube cells by septate desmosomes. A nerve, the foveal nerve, containing axons with neurosecretory vesicles occurs in the vicinity of the foveal gland. The secretory activity of the pheromone glands seems to be partially, if not entirely, under a neural regulation.
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  • 96
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    Journal of Morphology 193 (1987), S. 329-329 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 97
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    Journal of Morphology 194 (1987), S. 275-286 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of cells and the organization of axons were studied in Golgi-Colonnier and toluidine blue stained preparations from the medial cerebral cortex of the lizard Lacerta pityusensis. In the medial cortex, six strata were distinguished between the superficial glial membrane and the ependyma. Strata I and II formed the outer plexiform layer, stratum III formed the cellular layer, and strata IV go VI the inner plexiform layer. The outer plexiform layer contained smooth bipolar neurons; their dendrites were oriented anteroposteriorly and their axons were directed towards the posterior zone of the brain. Five neuronal types were observed in the cellular layer. The spinous pyramidal neurons had well-developed apical dendrites and poorly developed basal ones. Their axons entered the inner plexiform layer and gave off collaterals oriented anteroposteriorly. The small, sparsely spinous pyramidal neurons had poorly developed dendrites and their axons entered the inner plexiform layer. The spinous bitufted neurons had well-developed apical and basal dendritic tufts. Their axons gave off collaterals that reached the outer and inner plexiform layers of both the dorsomedial and dorsal cortices. The sparsely spinous horizontal neurons had dendrites restricted to the outer plexiform layer. Their axons entered the inner plexiform layer. The sparsely spinous, multipolar neurons had their soma close to stratum IV and their axons entered the outer plexiform layer. In stratum V of the inner plexiform layer were large, spiny polymorphic neurons; they had dendrites with long spines, and their axons reached the cellular layer. On the basis of these results, we have subdivided the medial cortex into two subregions: the superficial region, which contains the neurons of the cellular layer and their dendritic domains, and the deep region, strata V and VI, which contains the large, spiny polymorphic neurons. The neurons in the medial cortex of these lizards resembles those in the area dentata of mammals. On this basis, the superficial region may be compared to the dentate gyrus and the deep region to the hilar region of the hippocampus of mammals.
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  • 98
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    Cell Motility and the Cytoskeleton 7 (1987), S. 87-93 
    ISSN: 0886-1544
    Keywords: movement ; flagellar ; beat, flagellar ; stigma ; high-speed microcinematography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chlamydomonas cells sucked onto micropipettes were filmed at 500 frames/sec and analyzed as to their forward beating mode. A comparison with freely swimming cells revealed that the flagella of the sucked cells beat in a normal threedimensional manner, with beat frequencies that correspond to those of freely swimming cells. Most beats were synchronous. but not symmetrical; cis- and trans-flagellum appear to beat in a slightly different manner. Some cells beat synchronously throughout, but mostly synchrony was interrupted by a single asynchrony or up to incessant asynchronies, caused by transient accelerations of the trans- (fo-) flagellum. Only rarely did cis- and trans-flagella have different but constant beat frequencies. Helical swimming of Chlamydomonas more likely is due to the beat asymmetries of the two flagella than to differences of beat frequencies. In our records, the stigma is on the inside of the helical swimming path.
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  • 99
    ISSN: 0886-1544
    Keywords: calcium ; protein phosphorylation ; TFP ; Triton-extracted model ; ciliary orientation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To explore possible roles of calmodulin in Ca2+-induced ciliary reversal, we tested the effects of calmodulin antagonists on Triton-extracted models of Paramecium. In the extracted models prepared by the method of Naitoh and Kaneko [Science 176:523-524, 1972], the Ca2+ -induced ciliary reversal was not inhibited by calmodulin antagonists, trifluoperazine (TFP), or 5-chloro-l-naphthalenesulphone amide (W-7). However, in the presence of adenosine 3′,5′-cyclic mono-phosphate (cAMP), whose concentration is below the one that alters the ciliary direction, TFP inhibited ciliary reversal and the models swam forward at 10-5 M Ca2+. When the washing medium in the preparation of the extracted models was replaced with one containing MgCl2, the extracted model showed sensitivity to calmodulin antagonists without addition of cAMP; at 10-5 M Ca2+, 40 μM TFP or 100 μM W-7 inhibited the ciliary reversal and the models swam forward. Such effect of antagonists was abolished by an inhibitor of cAMP-dependent protein kinase. On the other hand, addition of cAMP enhanced the inhibitory effect of antagonists. These results suggest that calmodulin antagonists act to increase the extent of cAMP-dependent protein phosphorylation that inhibits the Ca2+ -induced ciliary reversal.
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  • 100
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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