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  • 1985-1989  (1,582)
  • 1945-1949
  • 1986  (1,582)
  • Life and Medical Sciences  (1,582)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 187 (1986), S. 159-172 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Teleost enameloid matrix has been proposed to be an ectodermal, mesodermal, or joint ectodermal-mesodermal product. To determine its origin we examined the ultrastructure of the inner dental epithelium (IDE), odontoblasts, enameloid, and dentin matrices of cichlid tooth buds at the stage of enameloid formation. © Alan R. Liss, Inc.Columnar IDE cells had apical and basal terminal webs and contained organelles associated with protein synthesis, including elongated secretory granules containing fibrillar material having cross-striations with 60-nm periodicity. The morphology of IDE secretory granules was typical of procollagen granules observed in a large variety of ectodermal and mesodermal cells synthesizing collagen. In contrast, the paucity of secretory granules within three odontoblast types indicates that these cells probably do not synthesize enameloid matrix. These observations are consistent with the idea that the bulk of the enameloid matrix is itself an ectodermal collagen synthesized and secreted by IDE cells.
    Additional Material: 22 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 187 (1986), S. 181-199 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology and fine structure of the basilar recess and basilar papilla were investigated in four species of salamanders from the family Ambystomatidae. The otic relationships of the recess and papilla to the proximal part of the lagena and saccule are described, and new terminology is suggested for the periotic relationships of the basilar recess to a diverticulum of an intracapsular periotic sac. The basilar papilla consists of supporting cells united laterally by gap junctions, capped by microvilli uniformly arranged around a short, central cilium, and hair cells that typically show several synapses with a single afferent nerve fiber, each marked by a rounded synaptic body surrounded by vesicles. In contrast to anuran basilar papillae, efferent nerve terminals were observed in synapse with hair cells and, rarely, upon afferent fibers. The distal half of the ambystomatid papilla contained hair cells capped by tall ciliary bundles, with kinocilia that show swellings near their tips with delicate attachments to adjacent tall stereocilia. A tectorial body covers only this region of the papilla. Hair cells with shorter stereocilia, situated in the proximal half and at the papillar margins, are related only to filamentous extensions of the tectorial body. The ambystomatid basilar recess and papilla are compared to auditory end-organs in other vertebrates, and it is suggested that a basic distinction can be made between aural neuroepithelia in amniotes versus that in nonamniotic vertebrate ears.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 187 (1986), S. 247-258 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Length-force relations, both active and passive, and twitch contraction characteristics were quantified for left medial gastrocnemius muscles of four young, four adult, and four old male Wistar rats. Muscle and bundle optimum length and muscle weight were also determined and subsequently used for calculation of a number of morphological characteristics of the muscles. Fiber optimum length was derived from muscle bundle optimum length. Generally, physiological characteristics remained constant during growth. There was no change either in active tension at muscle optimum length or in active working range relative to fiber optimum length, relative passive fiber stiffness, active force relative to passive force at optimum length, twitch contraction time and twitch half relaxation time at optimum length. A number of morphological changes, however, did take place in the medial gastrocnemius muscle during growth. Fiber optimum length increased but only by about 2 mm from youth to old age, whereas muscle optimum length increased by approximately 14 mm, presumably owing to extensive hypertrophy of the muscle fibers during growth. The priority for force of the medial gastrocnemius muscle (defined as the quotient of physiological cross-sectional area of a muscle and the cubed root of its volume, a measure independent of architecture and dimensions of muscles) increased during growth. This increase indicates that during growth the muscle shifts relatively more towards force generation than towards excursion generation. These findings are discussed in view of existing scaling theories.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986) 
    ISSN: 0362-2525
    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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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 187 (1986), S. 363-386 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An atlas of the brain of the horseshoe crab Limulus polyphemus is developed. All of the neuronal groups are identified and named, and regions of neuropil are segregated and named where possible. The nomenclature incorporates functionally neutral earlier names and assigns geographical names to newly distinguished structures. The atlas provides a basis for correlating the results of neuroanatomical, neurophysiological, and neurochemical studies, which yield information about individual neurons or groups of neurons in this species
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 1-13 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In addition to the supralabial glands (strips of glandular tissue lying along the maxilla), most snakes of the family Colubridae possess an enlarged oral gland lying behind the eye and emptying near the rear maxillary teeth, the Duvernoy's gland. Duvernoy's gland is most probably homologous to the venom gland of viperid and elapid snakes, and occasionally has been implicated in cases of human envenomation. Although of possible medical concern, there is reason to believe that secretion from this gland serves a biological role different from that of the venom gland, namely a role primarily in digestion rather then largely in rapid prey immobilization. The parenchyma of the Duvernoy's gland comprise two cell types, a serous cell containing numerous, electron-dense secretory granules, and myoepithelial cells. There are no mucous cells in the parenchyma; instead cells of this type are located exclusively in the lining epithelium of the main duct. Numerous unmyelinated nerves pass between secretory acini. Observations of the supralabial gland reveal that this gland, in addition to serous cells, also contains mucous cells and a putative third cell type we designate as an intermediate cell.In cellular morphology, Duvernoy's gland is closest to the venom gland of elapids, and least like the venom gland of viperids. Compared to the venom glands in both families of venomous snakes, Duvernoy's gland lacks a large luminal secretory reservoir. Emptying of Duvernoy's gland is thought to involve release of secretion granules into the lumen, and movement of the secretory product from there may be supplemented by mechanical pressure exerted externally by nearby contracting striated mucles. These differences in structure and mechanism of secretion release are taken as evidence that although they are homologous, the two types of glands, Duvernoy's and venom glands, are functionally distinct.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 69-78 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Regional differences of the surface of planarian gastrodermal cells are emphasized by staining with ruthenium red (RR). It is proposed that such differences reflect functional diversity of the luminal, lateral, and basal surfaces of the cells. The luminal surface is coated with a uniform layer of the RR-positive substance, which penetrates into the intercellular space at the intermediate junction. The septate junction situated just beneath the intermediate junction shows a permeability barrier to the RR tracer. At the basolateral surface, however, RR stains the septate junction in which the electron density of individual septa is enhanced remarkably. The gastrodermal cells are delineated entirely with RR-positive substance passing freely through the gap junction fuses into the outer leaflets of adjacent plasma membranes. The irregularly dilated intercellular space at nonjunctional appositions includes a slight deposit of RR-positive substance which attaches to the plasma membrane. The basal surface is underlined by the continuous basal lamina, which consists of the lamina lucida and the lamina densa. The lamina densa has a conspicuous affinity for RR. The lamina lucida is characterized by irregular deposits of RR-positive substance, some of which concentrates on the hemidesmosomal portions. Treatment with the enzyme hyaluronidase prior to staining with RR abolishes the staining of the basal lamina. As a result, the material of the lamina densa appears flocculent.
    Additional Material: 18 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986) 
    ISSN: 0362-2525
    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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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 129-156 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology and histology of the tongue in Sphenodon punctatus are described and used to infer function and to determine character state polarities in lepidosaurs. The tongue lacks an anterior notch and is covered with filamentous papillae, including specialized gustatory papillae containing taste buds. Lingual glands are restricted to mucocytes covering the papillae. Three intrinsic tongue muscles are identified and shown to be discrete fiber systems and not merely elaborations of the M. hyoglossus. These muscles interact with a connective tissue skeleton, particularly three septal planes, to cause changes in tongue shape. Tongue protrusion is probably caused by hyoid protraction and contraction of posterior genioglossus fibers; retraction by hyoid retraction, hyoglossus contraction, and contraction of anterior genioglossus fibers.It is argued that taste is important in prey discrimination and possibly in courtship. Vomeronasal function is probably mediated by inhalation and not tongue movement.Insertion of genioglossus fibers into the buccal floor is a derived feature of lepidosaur tongues. Derived features of squamate tongues include an anterior bifurcation, a divided genioglossus comprising medial and lateral portions, ventral transverse and circular muscle fiber systems around the hyoglossus, and the presence of a median septum. The tongue of the squamate family Iguanidae shares many plesiomorphic features with Sphenodon.
    Additional Material: 27 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 191-201 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The epithelium of the ileum of Locusta migratoria is composed of a single layer of columnar cells surrounded on the luminal side by cuticle and on the haemocoel side by a circular muscle layer. Where the circular muscles contact the epithelium, longitudinal muscles are present and the epithelium is slightly reduced. Elsewhere, a subepithelial sinus separates the epithelium from the circular muscle layer. The epithelial cells are characterised by extensive infoldings of the apical and basal cell membranes, which in the latter case, produce a maze of interconnecting channels and spaces. Mitochondria are closely associated with both apical and basal infoldings, although the bulk of these organelles is located in the cytoplasm underlying the infoldings of the apical plasma membrane. Vesicles of assorted sizes occur throughout the cytoplasm. They are particularly abundant in the apical region, where they appear to be produced by pinocytosis. Larger vesicles, containing either material of varying electron density or smaller vesicles, occur in the medial and basal regions of the cells. The contents of some of these vesicles have, in section, a lamellar appearance, composed of concentric layers of material. Similar vesicles are present in the basement membrane as well as the cells and connective tissue of the subepithelial sinus. Microtubules and groups of ribosomes commonly occur throughout the cytoplasm, and lipid-like droplets are also present in some of the cells. Ultrastructural features of the epithelial cells are discussed in relation to current knowledge of the function of the ileum.
    Additional Material: 16 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 29-37 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This work is concerned with the ultrastructural organization and some histochemical features of the vacuolar cells of the demosponge Oscarella lobularis. Vacuolar cells are characterized by large clear vacuoles containing an aqueous fluid. They are commonly found in the mesohyl of this sponge and tend to constitute a sort of parenchyma in the choanosome. Mobile cells of the mesohyl appear to differetiate into vacuolar cells through the progressive formation of wide cytoplasmic lacunae. We have identified four types of cells showing progressive transformation toward the vacuolar cell type. Precursors (types 1-4) of the vacuolar cells probably derive from endopinacocytes, since they share several histochemical and ultrastructural characteristics with them. Our data support the notion that vacuolar cells are involved in the synthesis of collagen, act as a mechanical support of the sponge body, and are eventually extruded from the sponge through the canals of the aquiferous system.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 51-67 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The innervation of the mandibular nerve of the worker honey bee was investigated primarily with methylene blue vital staining. Results on the motor innervation were compared with those of earlier work, yielding some corrections and new findings. The nerve to the mandibular abductor muscle not only carries motor fibers but also supplies sensory branches to the head integument and to the presumptive proprioceptors which probably monitor movements of the proboscis. A small neural mass which is equipped with two systems for proprioception is situated at the point where the mandibular nerve divides into its major branches. One system is composed of receptor muscles stretched between the anterior tentorial arm (AT) and the mandible and multipolar cells. The other is composed of elastic strands between AT and the apodeme of a smaller branch of the mandibular adductor and tripolar cells. The former is stretched by mandibular abduction and the latter by adduction. The two systems collectively are called the mandibular muscle receptor organ. There are two groups of receptor muscles: the outer receptor muscle, which is located outside the neural mass, and the inner receptor muscle located within. Only the latter is innervated by multipolar cells. Another, single, multipolar cell is attached to the surface of the tendon of the inner receptor muscle. A further pair of bipolar-multiterminal cells attaches to the epidermis at the extremity of the apodeme of the mandibular adductor. One originates from the mandibular nerve and the other from the labral nerve. Both presumably respond to the epidermal expansion caused by mandibular abduction.
    Additional Material: 15 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 157-165 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A tympanohyal bone is reported in dolphins for the first time. The exceptional occurrence of this element in the bottlenose dolphin (Tursiops truncatus) and its location in a furrow of the tympanic can be taken as a vestige of an ancestral conformation indicating that, in cetacean ancestry, uncoupling of the periotic from the mastoid must have taken place laterally and dorsally to attachment of the hyoid arch and the stylomastoid foramen. There is a good correspondence between morphology and topographical relations of structures surrounding the facial canal in toothed whales and terres-trial mammals (especially perissodactyls and artiodactyls).During early cetacean evolution, the tympanic had to undergo strong modification because of its functional correlation with the periotic. In precetaceans, the tympanic was probably loosely attached to neighboring skull bones, while at the same time it was suspended from the periotic via the tympanohyal. The earliest known cetaceans obviously lost this indirect osseous suspension but retained the peripheral attachments of the tympanic. In advanced archeocetes, two of these attachments are maintained but have shifted onto the periotic. In modern dolphins, the tympanic is in firm osseous contact exclusively with the periotic (tympano-periotic complex). Both elements are isolated from the skull acoustically and form a separate mechanical unit specialized for high-frequency underwater sound perception.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 179-189 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the morula cells of Eupentacta quinquesemita and the distribution of these cells in the dermal connective tissue are described. Morula cells are abundant in the dermis and appear to function in the maintenance of the extracellular matrix (ECM) as a source of ground substance material. The synthetic activity of these cells is described in detail. Morula cells are filled with large secretory vesicles containing three electrondense materials which are derived from rough endoplasmic reticulum and Golgi activity. The synthetic product of these cells contains glycosaminoglycans and is secreted into the ECM by degranulation. The ultrastructural and histochemical similarity of the degranulation product to the ECM ground substance suggests that they are comprised of the same material. Morula cells appear to function primarily in connective tissues where ground substance predominates. The cells often contain secretory vesicles at various stages of formation, all of which eventually mature and degranulate. The synthetic pathway of the morula cells appears to result ultimately in the complete disruption and death of the cells. The function of morula cells in the holothuroid ECM is discussed, and the synthetic activity of the cells is compared with that of other secretory cells.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986) 
    ISSN: 0362-2525
    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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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 239-250 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Early events during mouth formation in embryos of the starfish Pisaster ochraceus have been studied with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Embryos examined by TEM were fixed in glutaraldehyde with Alcian blue, a dye which preserves extracellular materials. Initially, mesenchyme cells migrate off the tip of the archenteron, leaving a defect in the cell layer that is covered by the basal lamina. This region of “naked” basal lamina bulges into the blastocoele and forms a hemispherical blister. At the same time that this is occurring, filamentous and conical processes extend from the inner surface of the presumptive stomodeal ectoderm cells which are located directly opposite the bulge of basal lamina. These processes penetrate the ectodermal basal lamina and project “naked” plasmalemma into the blastocoele. Shortly after this, the blister of endodermal basal lamina becomes irregular in shape, and scattered cells are found both within the blister and between it and the presumptive stomodeal ectoderm cells. Processes of endodermal cells appear to make contact with the filamentous processes of the stomodeal ectoderm cells. In other embryos which appear to be at a slightly later stage, the free basal lamina is conical in shape and is associated with at least one conical ectodermal process. In yet other embryos, the free endodermal basal lamina is either in contact with several other large processes forming a circular region of contact, or the free endodermal and ectodermal basal laminae are fused at the edge of the circle. Degeneration of both the ectodermal and endodermal basal laminae located within the circle, and subsequent invagination of the stomodeal ectoderm, appear to complete this process. The pulsations of stomodeal ectodermal cells seen throughout early stages in mouth formation may be involved in these events.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 327-333 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vascularization of the distal accessory flexor muscle (DAFM) in the walking legs of the lobster, Homarus americanus, was examined with dye injection and electron microscopy. Vascularization of this flat, thin DAFM is via two vessels, one supplying the tendinal region of the muscle and the other the exoskeletal region. The vessels that originate from the single major limb vessel, subdivide extensively over the DAFM and form a profuse network that has hitherto gone unnoticed. The degree of vascularization of individual fibers was determined by periodic sampling along its length with thin-section electron microscopy. At each and every sampling station, individual fibers had several (seven to eight), small-diameter (4 μm) blood vessels in their cross-sectional profile. In contrast, nerve terminals of the excitor and inhibitor axon were rarely encountered. This high degree of vascularization was found amongst fibers that are from different regions of the DAFM and differ in the performance of their excitatory synapse but are similar in their structural and contractile properties.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 199-213 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secondary palate of mammals is a bony shelf that closes the ventral aspect of the rostrum. The rostrum, therefore, approximates to a tapered semicylindrical tube that is theoretically a mechanically efficient structure for resisting the forces of biting, including the more prolonged bouts of mastication typical of mammals. Certain mammal-like reptiles illustrate stages in the development of the palate in which the shelves projecting medially from each premaxilla and maxilla do not meet in the midline. We evaluate several geometric properties of sections through the rostrum of the American opossum (Didelphis virginiana). For loading at the incisors and canines, these properties indicate the structural strength and stiffness in both bending and torsion of the rostrum and of single maxillae. We then repeat the analysis but progressively omit segments of the palatal shelf, a procedure which simulates, in reverse, the evolutionary development of the structure. The results demonstrate that the secondary palate contributes significantly to the torsional strength and stiffness of the rostrum of Didelphis and to the strength of each maxilla in lateromedial bending. The major evolutionary implications of the results are that the rapid increase in rostral strength with small increments of the palatal shelves may have been a significant factor in the development of the complete structure. The results indicate that there was a marked jump in torsional strength and stiffness when the shelves met in the midline, which is likely to have been important in the subsequent development of the diverse masticatory mechanisms of cynodonts and mammals. On the basis of this analysis the mammalian secondary palate may be interpreted as one of a number of methods, seen in the mammal-like reptiles, for strengthening the rostrum.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 327-346 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Data from adult birds, crocodilians, Sphenodon, squamates, turtles, and from the chick embryo are compared to test conflicting hypotheses of homology of the deep dorsal thigh muscles of birds and other reptiles. This comparison suggests that: (1) avian Mm. iliofemoralis externus and iliotrochantericus caudalis (herein renamed “iliofemoralis cranialis”) are homologous with M. iliofemoralis of other reptiles; (2) avian Mm. iliotrochanterici cranialis and medius are homologous with one of two divisions of M. pubo-ischio-femoralis internus found in other reptiles (pars dorsalis of Crocodylia); (3) avian M. iliofemoralis internus (herein renamed “cuppedicus”) is homologous with the other division of M. pubo-ischio-femoralis internus (pars medialis of Crocodylia). This hypothesis implies a minimum of seven transformations in the number of muscles and their positions of origin and insertion in the evolution of Aves, five of which are recapitulated during ontogeny of the chick. The traditional recognition of three muscles in the “iliotrochantericus group” is topographically accurate, but it is a misnomer and has been a source of misdirection when these muscles are studied in a phylogenetic context. Variations within Aves in the presence of the iliotrochantericus muscles (cranialis or medius) and the iliofemoralis muscles (externus or cranialis) are results of heterochronic perturbations of a conserved developmental program. Unlike most previous interpretations, this view of homology suggests that the evolution of avian bipedality was accompanied by few myological transformations, despite profound modification of the skeleton.
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  • 20
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 1-8 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the parathyroid glands was studied in chick embryos developing normally in ovo or in shell-less culture (after removal of the eggshell). Shell-less chick embryos are significantly hypocalcemic relative to their in ovo counterparts. At 12 days of incubation, the parathyroid glands of shell-less embryos contain more lipid and show evidence of increased protein synthetic activity relative to those grown in ovo (more rough endoplasmic reticulum, presence of some dense secretory granules). The glands from in ovo embryos do not contain secretory granules at this age. At 15 days of incubation, the in ovo glands have developed signs of protein synthetic activity similar to those of the 12-day shell-less embryos. However, the parathyroids of the 15-day shell-less embryos appear strikingly more active than at 12 days, containing stacks of concentric RER membranes and increased numbers of secretory granules. By 18 days of incubation, the ultrastructure of the glands of the two groups is indistinguishable, both appearing to be more active than the 15-day shell-less group. Thus, protein synthetic activity of the parathyroid glands, as detected by ultrastructural alterations of the chief cells, normally appears to be initiated during the latter part of embryogenesis (by approximately 15 days incubation) and its onset can be stimulated at least 3 days prematurely by hypocalcemia.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), 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 morphology of the opercularis system of anuran and caudate amphibians suggests that it acts to produce motion of the operculum that in turn produces fluid motion within the inner ear. The operculum and opercularis muscle form a lever system, with a narrow connection between the operculum and otic capsule acting as a fulcrum about which the operculum moves in response to forces applied via the muscle. The opercula of many species possess a muscular process on which the muscle inserts, thereby increasing the moment arm through which the muscle acts. The tonicity of the opercularis muscle allows tensile forces produced by substrate vibration or other mechanical energy applied to the forelimb to be effectively transmitted to the operculum; the elasticity of the connective tissue holding the operculum in place should act to return the operculum to its original position. The opercularis systems of frogs and non-plethodontid salamanders are similar structurally and functionally; that of plethodontid salamanders is structurally distinct but also functions as a lever system. Fluid motion produced by opercular motion could stimulate various end organs of the inner ear; the saccule, lagena, and amphibian papilla are in close approximation and wave energy could directly affect their otoconial or tectorial structures. In those anurans with a tympanic ear, the stapedial footplate and operculum articulate, but this articulation allows both to move independently. The stapes-tympanum complex and opercularis system therefore appear to be independent functional systems, and it is unlikely that the opercularis system modulates middle ear responsiveness. The general design of the opercularis system is consistent with a function in reception of substrate vibrations.
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  • 22
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    Journal of Morphology 190 (1986), S. 191-200 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Species of the salamander genus Plethodon have a characteristically uniform morphology. Morphological conservatism at the level of interspecific comparisons, however, is not always reflected within species. Perhaps the most extreme example of intraspecific variation is the recent description of extensive variability in limb-skeletal patterning both within and between populations of the widespread species P. cinereus. We utilized limb regeneration following experimental amputation as a tool (1) to examine whether naturally occurring variant skeletal patterns result from limb loss and regeneration in nature, and (2) to assay the intrinsic (i.e., genetic) component of between-individual variation in mesopodial patterning. We observed the following. First, regenerate patterns are strikingly different from native patterns: interelement fusions in regenerates are typically between proximodistally adjacent cartilages, whereas interelement fusions in native variant limbs occur exclusively between laterally adjacent cartilages. Fusions also are over ten times more frequent in regenerates than in native limbs. Second, there is no strong correlation between native limb pattern (typical vs. variant) and the regenerate pattern. We conclude that variability in field-collected P. cinereus reflects extensive intrapopulation variation in limb-skeletal patterning during original limb development, rather than regeneration in nature, and that limb regeneration analysis provides no evidence of a strong genetic component to between-individual variation. Finally, unusual mesopodial patterns produced during limb regeneration may be related to the mechanical factors impinging on the regenerating limb in this terrestrial species.
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  • 23
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    Journal of Morphology 190 (1986), S. 215-241 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The centra of Lepisosteus are perichondral ossifications of arcualia (i.e., arcocentra), whereas those of Amia are direct perichordal ossifications (i.e., autocentra) that enclose the arcualia. The preural centra of Lepisosteus are monospondylous, whereas the ural centra are formations of inter- and basidorsal arcualia. In contrast, the preural centra of Amia are diplospondylous, whereas preural centrum 1 (and sometimes preural centrum 2) and ural centra are monospondylous. The ural centra of Lepisosteus are expansions of dorsal arcualia, but those of Amia are expansions of the basiventral autocentrum. This explains the fusion of the neural arches with the ural centra and the presence of autogenous hypurals in Lepisosteus, in contrast to the situation in Amia in which the compound ural neural arch (the fused ural neural arches) is free, and the hypurals are fused to the ural centra. Lepisosteus possesses true epurals, which are modified neural spines, whereas in Amia the “epurals” are positioned between the neural spines like radials. Lepisosteus and Amia possess a polyural caudal skeleton with a one-to-one relationship between ural centra and hypurals; the number of hypurals may be reduced in adult Lepisosteus.
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  • 24
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Samples of perirenal adipose tissue were obtained from four fetuses from each of seven crossbred gilts at each of three stages of gestation: 70, 90, and 110 days. Samples were routinely prepared for histochemistry and histology. At each age, the largest fat cell clusters were consistently located near points where large blood vessels entered the loose connective tissue. Cell-cluster size decreased with distance from the entry points of large blood vessels. Fat cells proximal to entry points of large arterioles and fat cells distal to entry points of large arterioles were the same size. Enzyme cytochemistry disclosed that reactions for glucose-6-phosphate dehydrogenose (G6PDH), lipoprotein lipase (LPL) and NADH-TR enzymes were reduced in distal (relative to entry points of large arterioles) adipocytes compared with proximal adipocytes. Reactions for succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) in adipocytes were not influenced by location within the tissue. Small fat cell clusters with sparse capillary beds surround arterioles in distal areas of sections from fetuses at 70, 90, and 110 days of gestation. In the proximal areas of sections from 110-day-old fetuses, arterioles were surrounded by large fat cell clusters with dense capillary beds. These characteristics serve to distinguish perirenal depots from subcutaneous depots in the fetus.
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  • 25
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    Journal of Morphology 190 (1986), S. 297-305 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In an effort to understand the variation and probable origin of a female copulatory organ found in isopods of the asellote superfamily Janiroidea, the morphology of female reproductive structures among the Asellota was surveyed. Examples of four asellote superfamilies were studied using whole mount staining after potassium-hydroxide maceration or clearing with lactic acid. In contradiction to previous conclusions, the cuticular organ is shown to occur in the more primitive Asellota, although the position of its opening varies considerably. In the genera Asellus, and Stenetrium, Munna, and Santia, the cuticular organ originates adjacent to the oopore, and in the remaining janiroidean isopods, it is placed dorsally and usually anteriorly. This information permits a simple hypothesis explaining the origin of the cuticular organ: it was present in the proximate ancestor of the Asellota and evolved to the janiroidean condition by anterodorsal migration.
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  • 26
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    Journal of Morphology 190 (1986), S. 325-333 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spinal cord of two tetraodontiform fishes, the Japanese file fish (Navodon modestus) and the panther puffer (Takifugu pardalis), are unusual among vertebrates in having a markedly abbreviated spinal cord with a long and flattened filum terminale. Only the rostral short part of the cord of both species is cylindrical; the greater part of the cord is markedly flat. The majority of the spinal nerve roots leave the short cylindrical part. The flattened part of the cord contains the central canal, myelinated nerve fibers, and a few motoneurons surrounding the cauda equina, and it is histologically similar to the filum terminale of amphibians and mammals. The spinal cords of other teleosts, the sun-fish and angler, also are abbreviated and possess a filum terminale and cauda equina. These orders possess an enormous head and short trunk. However, the correlation between this body form and an abbreviated cord is not causal, since the tetraodontiform species described here show ordinary body proportions. The spinal cord may be abbreviated in tetraodontiform fishes in general.
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  • 27
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    Journal of Morphology 190 (1986), S. 237-248 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Estivation in Protopterus is an episodic event characterized by elaboration of a cocoon as ambient water is withdrawn, a state of torpor, and distinctive cardiorespiratory and metabolic changes. Among the more striking of these features is a decrease in oxygen consumption, a complete reliance on air breathing to satisfy metabolic need, a slowing of the heart rate, and a drop in blood pressure. The initiating mechanism for these dramatic changes is not known. As yet, specific “estivating factors” have not been identified. However, the pattern of decrease in oxygen uptake during estivation and starvation are quite similar, suggesting that a common factor may be involved in both. Attempts to implicate suppression of thyroid function in the onset of estivation have been unconvincing. Although initiating mechanisms for estivation in Protopterus remain uncertain, once estivation sets in a variety of adaptive changes occur that enable the estivating lungfish to survive for months to years without ingesting food or water. Among these are oliguria and a shift in metabolic pathways. Although estivation in Protopterus has been characterized with respect to cardiorespiratory and metabolic parameters, no attempt is made to extrapolate from the biologic processes in Protopterus to other lepidosirenid lungfish or to other genera.
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  • 28
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    Journal of Morphology 190 (1986), S. 305-373 
    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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  • 29
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    Journal of Morphology 187 (1986) 
    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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  • 30
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    Journal of Morphology 187 (1986), S. 1-21 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cephalic muscles in three species of Entechinus, two species of Opheodrys, and Symphimus mayae display patterns of interspecific variation that are largely congruent with patterns of variation previously described for the skulls of these species. This congruence does not stem from direct correlation between the shapes of associated bones and muscles. In these colubrid snakes, most interspecific variations in muscle form involve changes in the shape or relative position of attachment points that appear unrelated to changes in the gross form of the bony surfaces forming the attachment points and produce no major changes in the architectural array of fibers in the muscle. Data presented here, combined with information from previous comparative studies of colubroid cephalic muscles, support the hypothesis that these muscles are limited in their potential variability by factors favoring parallel arrangements of fibers.
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  • 31
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    Journal of Morphology 187 (1986), S. 51-60 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Formation of lateral vessels in the esophageal region of Prosorhochmus americanus embryos and coelomogenesis in the pygidial region of larval Magelona sp. are examined and compared. Earliest vessel rudiments of P. americanus are composed of a compact band of mesodermal cells (mesodermal band), lying on a layer of extracellular matrix (ECM) and lacking intercellular junctions. Rudiments are surrounded by presumptive muscle cells. Rudiments at later stages of differentiation possess lumina of differing sizes formed by a separation of apposing cell apices (schizocoely). Aohagrens junctions are apparent between lining cels of vessels following cavitation, and overlying muscle cells exhibit many myofilaments. Mesodermal bands of the recognized coelomate, Magelona sp. consist of glycogen-rich, mesodermal cells resting on ECM and joined by adhaerens junctions. Some of the cells possess a rudimentary cilium. Coelom formation occurs as a splitting of the cell band as is the case for P. americanus. Recognition of an accepted mode of coelomogenesis in P. americanus, correlated with morphological details of adult nemertine vessels, affirms the view that nemertine vessels are coelomic homologues.
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  • 32
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    Journal of Morphology 187 (1986), S. 23-37 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Eggs of the asteroid Pisaster ochraceus demonstrate cortical granules, a thick vitelline membrane, and a poorly stained jelly coat similar to that seen on the eggs of other echinoderms. When fixed in the presence of alcian blue the jelly coat is seen to be made up of three regions, an inner layer consisting of a meshwork of fibres, a middle layer of thicker fibres, and a dense outer layer. At fertilization the cortical granules release their contents into the potential space between the vitelline layers and a low fertilization membrane consisting of the vitelline layer and a dense component of the corticle granule is formed. Initially the remaining contents of the corticle granules form an amorphous hyaline layer that fills the space between the plasma membrane and the fertilization membrane. At hatching a distinct hyaline layer is present. It persists at least to the bipinnaria stage and consists of four distinct layers. A similar layer is also located over much of the early embryonic endoderm but is lost from the regions involved in the formation of the mesenchyme cells, coelom, and mouth just before these events take place. Numerous large clear vesicles are located in the apex of all cells associated with a hyaline layer. Where the hyaline layer is lacking, only scattered vesicles are present suggesting that the vesicles may be involved in maintenance of the layer. Attempts to identify elements of the hyaline layer by immunofluorescence demonstrated that it appears to bind both antisera and control sera in a nonspecific manner.
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  • 33
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    Journal of Morphology 187 (1986), S. 39-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Six fiber types have been described in the ambiens muscle of red-eared turtles. These include one slow oxidative type, two fast oxidative types, two fast oxidative and glycolytic types, and one fast glycolytic type. Fiber types are non-randomly distributed throughout cross sections of the muscle. There is a decreasing gradient of oxidative staining and an increasing gradient of glycolytic staining along an axis from the superficial to deep regions of the muscle. The slow oxidative fibers are predominantly located within one or two fascicles of the superficial surface of the muscle. The fast glycolytic fibers are predominant in deep fascicles.In contrast to previous reports of histochemically monotypic intrafusal fibers in turtle muscle, ambiens muscle spindles have been observed containing one to eleven intrafusal fibers, including two fiber types. Fiber diameter and area are consistently smaller than observed in most extrafusal fibers. Spindles are predominantly located in superficial and cranial fascicles of the ambiens muscle and are located in regions characterized by extrafusal fibers with high oxidative activity.
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  • 34
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    Journal of Morphology 187 (1986), S. 109-121 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural examination of the head kidney of Periophthalmus koelreuteri (Pallas) (Teleostei, Gobiidae) revealed that the nephronic tubule cells are bound by tight junctions and desmosomes with little intercellular space. The first proximal segment (PI) consists of low columnar cells with well developed brush borders, indented nuclei, and numerous apical endocytic vesicles and lysosomes. A second cell type possessing clusters of apical cilia and lacking brush border and lysosomes is occasionally found between PI cells. The second proximal segment (PII) is formed of high columnar cells with brush border, regular spherical nuclei and numerous mitochondria located between well developed infoldings of the basal membrane. Single ciliary structures protrude into the lumen from PI and PII cells. The distal segment is lined by low columnar epithelium with few microvilli, regular spherical nuclei, numerous scattered mitochondria, and microbodies. The collecting tubule cells are cuboidal with few euchromatic nuclei, some mitochondria, and secondary lysosomes.
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  • 35
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    Journal of Morphology 187 (1986) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 36
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    Journal of Morphology 187 (1986), S. 81-108 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The feeding mechanism of the South American lungfish, Lepidosiren paradoxa retains many primitive teleostome characteristics. In particular, the process of initial prey capture shares four salient functional features with other primitive vertebrates: (1) prey capture by suction feeding, (2) cranial elevation at the cranio-vertebral joint during the mouth opening phase of the strike, (3) the hyoid apparatus plays a major role in mediating expansion of the oral cavity and is one biomechanical pathway involved in depressing the mandible, and (4) peak hyoid excursion occurs after maximum gape is achieved.Lepidosiren also possesses four key morphological and functional specializations of the feeding mechanism: (1) tooth plates, (2) an enlarged cranial rib serving as a site for the origin of muscles depressing the hyoid apparatus, (3) a depressor mandibulae muscle, apparently not homologous to that of amphibians, and (4) a complex sequence of manipulation and chewing of prey in the oral cavity prior to swallowing. The depressor madibulae is always active during mouth opening, in contrast to some previous suggestions.Chewing cycles include alternating adduction and transport phases. Between each adduction, food may be transported in or out of the buccal cavity to position it between the tooth plates. The depressor mandibulae muscle is active in a double-burst pattern during chewing, with the larger second burst serving to open the mouth during prey transport. Swallowing is characterized by prolonged activity in the hyoid constrictor musculature and the geniothoracicus.Lepidosiren uses hydraulic transport achieved by movements of the hyoid apparatus to position prey within the oral cavity. This function is analagous to that of the tongue in many tetrapods.
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  • 37
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    Journal of Morphology 187 (1986) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 38
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    Journal of Morphology 187 (1986), S. 239-246 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In addition to the cholinergic innervation described in the sphincter of the efferent filament arteries (Bailly and Dunel-Erb, ′86), an aminergic component has been demonstrated by specific techniques. The Falck fluorescence technique reveals a network of nerve fibers displaying a green fluorescence characteristic of catecholamines. At the ultrastructural level two types of fibers are present, one with clear vesicles and another with densecored vesicles. Axo-axonal synaptic relationships exist between the two types. Results of 5- and 6-OHDA (hydroxydopamine) treatments confirm the presence of an aminergic component.These observations support the notion of a dual innervation: cholinergic and adrenergic of, respectively, parasympathetic and sympathetic origin. The presence of presynaptic modulation is suggested. The aminergic component could inhibit or reduce the release of acetylcholine from cholinergic nerve endings. These results suggest that the sympathetic innervation modulates the vasoconstriction effect of the parasympathetic component.
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  • 39
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    Journal of Morphology 187 (1986), S. 143-158 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Among the acanthopterygian fishes, the Labridae possess the most highly integrated and specialized pharyngeal jaw apparatus. The integrated feature involves many osteological components and aspects of muscle form, architecture, composition, and function. The upper jaw articulates by means of a true diarthrosis with the pharyngeal process of the parasphenoid, whereas the lower jaw has established physical contact with the cleithrum. Complex muscle fusions have contributed significantly in the development of a double muscle sling operating the lower jaw. The original levator externus 4 fuses with the central head of the obliquus posterior, whereas the original levator posterior combines with the lateral head of the obliquus posterior as well as with the adductor branchialis 5.During the masticatory cycle, both upper and lower jaws undergo complex movement orbits resulting in shearing and crushing functions. Shearing occurs as the forward moving upper jaw collides with the dorsally held lower jaw. Crushing is effected by an extreme posterodorsal movement of the lower jaw against the retracted upper jaw, thereby establishing full occlusion of the teeth.The specialized morphological and functional design of the labrid pharyngeal jaw apparatus is similar to that found in cichlids. In sharp contrast to primitive acanthopterygian fishes, the Labridae and Cichlidae exhibit a spectacular morphological diversity that parallels their ecological diversification. Our combined functional and historical analysis has established a correlation between the complex integration of the pharyngeal jaw apparatus and morphological and ecological diversity in the Labridae and Cichlidae.
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  • 40
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    Journal of Morphology 187 (1986), S. 219-237 
    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 shown the existence of a sphincter in the efferent filament artery of the teleost gill and its constrictory response to acetylcholine (ACH) and vagal stimulation. This study deals with the muscular organization of this sphincter and the distribution of its innervation as elucidated by degeneration methods and cytochemistry. The sphincter innervation is supplied by the protrematic vagus nerves. Nerve endings filled with cholinergic-type vesicles are located in close association with the adventitial smooth muscle cells and display a strong acetylcholinesterase (ACHE) activity. Section of the protrematic vagus nerve induces a nearly complete degeneration of the sphincter innervation. ACHE-positive nerve cell bodies are present both in the sphincter area and in the protrematic vagus nerve. These results suggest that innervation of the sphincter in the efferent filament artery is cholinergic through the activity of postganglionic axons of the parasympathetic system.
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  • 41
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    Journal of Morphology 187 (1986), S. 289-299 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dramatic depression in granule volume density and size was measured in acinar cells of postnatal rat pancreas following the initiation of feeding. Volume density decreased about threefold from 45% at birth to 16% 2 days thereafter. Mean granule diameter decreased from 1.50 μm to 0.80 μm, an 85% decrease in corresponding granule volume. At the same time, numerical density approximately doubled. At 2 days after birth, cells with smaller granules had lower volume densities, and differences in mean granule volume between cells accounted for most of the differences in volume density. Although the distribution of granule diameter in newborns was lognormal, the distribution at 2 days was heavily skewed to larger sizes. This was the result of skewed distributions within individual cells and not an artifact of sampling. The results corroborate the central role of granule volume in determining changes in the volume density of zymogen granules in the pancreas and suggest that zymogen granules can act as capacitors that can change size as a function of the enzyme contained within.
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  • 42
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    Journal of Morphology 187 (1986), S. 321-342 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparative study of four genera of arvicolid rodents (Clethrionomys, Eothenomys, Alticola, and Synaptomys) presents the first complete description of limb myology for any member of this recently evolved, highly successful family. The study also identifies four forelimb and four hind-limb muscles that exhibit characters of value to systematic analyses within the group. In no instance was postcranial myology sufficient to distinguish among species of Clethrionomys or to distinguish Clethrionomys from Eothenomys. Moreover, in some instances Synaptomys, a genus traditionally presumed primitive within the family, possessed the apomorphic condition for a myological character when compared to the four genera of cricetine rodents that served for outgroup comparisons.
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  • 43
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    Journal of Morphology 188 (1986), S. 15-28 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Egg capsules of Syndisyrinx franciscanus, an intestinal parasite of sea urchins (Strongylocentrotus spp.), consist of a bulb, which contains the embryos, and a stalk-like filament. The wall of the bulb is about 12 μm thick and is composed of sclerotized proteins. The end of the bulb opposite the attachment of the filament bears a reticulum of hatching sutures. Transmission electron microscopy discloses that hatching sutures traverse the entire thickness of the capsule wall. The inner 9-10 μm of sutures are a uniform 20 nm in width and contain a trilaminar cementum. The outer 2-3 μm of sutures are 15 nm to more than 500 nm in width and contain an electron-lucent cementum. The latter may contain an irregular, median, electron-dense layer or, more commonly, electron-dense granules. The outside of some capsules is partially covered by a thin, electron-dense material.A previous study showed that sutures in intact capsules of Syndisyrinx franciscanus are not affected by host digestive fluids, but are severely weakened immediately prior to hatching owing to activities of the embryos. The hypothesis that the embryos secrete a hatching enzyme is supported by findings that sutures of intact capsules are not affected by externally applied trypsin, but become weakened when capsules are cut open and then incubated in trypsin. Scanning electron microscopy reveals that the outer parts of sutures often remain intact after hatching. We hypothesize that the ability of sutures to resist enzymatic attack from the outside, but not the inside, results from differences in the chemical properties of the cementums in outer and inner parts of sutures.
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  • 44
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    Journal of Morphology 188 (1986), S. 225-238 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The iris of the toad Bufo marinus is directly photosensitive and will constrict in response to light striking only the iris. This is true even when the iris is isolated from the rest of the eye, and therefore from reflex neuronal influences initiated in the retina. This autonomous response is probably mediated by the sphincter pupillae muscle, since no specialized photoreceptors are present in the iris, nor does the sphincter exhibit any specializations likely to subserve a purely photoreceptive function. The photosensitive sphincter appears typical of smooth muscle and, like mammalian sphincters, possesses many intercellular junctions. The iris possesses a well-developed neuronal plexus with fibers projecting into the sphincter muscle layer. Nerve terminals contain small, agranular (30-70nm) and large, dense-cored (80-120nm) vesicles. No consistent postsynaptic specializations are seen on any cells of the iris, including the cells of the sphincter muscle. The anterior pigment epithelial cells of the iris appear specialized and resemble the myoepithelial dilator muscle described by Kelly and Arnold ('72) for the iris of rats.
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  • 45
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    Journal of Morphology 188 (1986), S. 289-302 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cell-lineage of Bithynia tentaculata L. has been studied through the formation of the fourth quartet of micromeres, i.e., the 81-cell stage. Up to the 28-cell stage, the cleavage pattern is radially symmetrical, and the divisions take place synchronously in the quadrants. Bilateral symmetry is established by the formation of the mesentoblast 4d at the future dorsal side. A resting stage preceding the formation of 4d is lacking. The mesentoblast 4d is formed earlier than the other fourth quartet cells, and it divides twice before 4a-4c are formed. Bilateral symmetry in the molluscan cross becomes apparent by different divisions of the tipcell and the basal cell in the dorsal arm. Dorsoventrality is progressively corroborated by the divisions in the second and third quartets of micromeres, which take a different course in the A and B quadrants on the one side and in the C and D quadrants on the other side.
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  • 46
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    Journal of Morphology 188 (1986), S. 303-313 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two modes of shedding of rod disc membranes were observed by electron microscopy in bullfrog retinas illuminated for various periods from 10 min to 2 hr. One mode is “autonomous shedding” whereby rods shed disc packets directly into the subretinal space. Most of the discarded disc packets are subsequently brought into contact with villous apical processes of pigment epithelial (PE) cells and are ultimately engulfed by these cells. When some of the shed disc membranes remain in the subretinal space, it appears that these remanants may be phagocytized by ameboid phagocytes. The other mode is “cooperative shedding” whereby rods shed disc packets with the participation of pigment epithelial ensheathment. Shedding of a disc packet from a rod tip, and enclosing of the rod tip by a broad, sleeve-like apical process of a PE cell, take place simultaneously. The separated disc packets may be immediately engulfed by the PE cells without risk of failure. Both villous and sleeve-like types of apical processes of PE cells in the bullfrog lack pigment granules, in contrast to the finger-like apical processes that do contain pigment granules. Villous and sleeve-like apical processes that do contain pigment granules. Villous and sleeve-like processes therefore probably belong to the same category as the leaf-like apical processes of PE cells in mammalian retinas.
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  • 47
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    Journal of Morphology 189 (1986) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 48
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    Journal of Morphology 189 (1986), S. 25-43 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: High-speed cinematography shows that Suncus murinus (Crocidurinae) masticates fast (mean 5.5, 5-10 masticatory cycles per sec). Their grasping behavior is not stereotyped. The unilateral mandibular movements combine vertical, anteroposterior, and lateral displacements; and any masticatory sequence may include crushing, repositioning, shearing, and grinding components. Size and consistency of food influence the duration of individual chewing cycles. As food is transferred to the new working side, the chewing direction reverses, either near maximum closure or near maximum opening. An unfused mandibular symphysis permits tilting movements of the two halves of the mandible. Food may be squeezed between the lower incisors. The working side tilts outward during closing; this may improve shearing or grinding action. The closing phase is posteriorly directed. Thus, the masticatory movements of these shrews differ from those that have been described in many other mammals.
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  • 49
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    Journal of Morphology 189 (1986), S. 67-70 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The presence of adrenergic innervation was investigated in four different vascular segments of the neotenic tiger salamander, Ambystoma tigrinum, by histofluorescent staining for catecholamines. The segments were the respiratory section of the gill, the branchial shunt vessels, a vascular plexus in the pulmonary artery, and the dorsal aorta. No adrenergic fibers were detected in the respiratory section of the gill or the pulmonary arterial plexus. In contrast, the branchial shunt vessels contained both adrenergic varicosities and catecholamine-containing cell bodies. These cells resemble Type I cells of the mammalian carotid body and amphibian carotid labyrinth. Adrenergic innervation of the dorsal aorta was sparse and restricted to the adventitia. The results suggest that adrenergic nerves may directly regulate blood flow in the gill, and thus gas exchange, by controlling vascular resistance of the branchial shunts. The contractile state of the dorsal aorta may also be under adrenergic control. In addition, it is suggested that the adrenergic cells of the branchial shunts may serve a receptor function in being sensitive to arterial blood gases.
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  • 50
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    Journal of Morphology 189 (1986), S. 89-98 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning and light microscopy investigations of the anterior alimentary canal of the pear psylla, Psylla pyricola Foerster (Homoptera: Psyllidae), revealed the morphology of the labium and stylets, as well as the presence of sensory structures and a valve in the precibarium. The labium consists of three telescoping segments with an internal labial groove, which surrounds and supports the stylet bundle. Also a part of the labial groove is the internal labial clamp. The stylet bundle is comprised of paired styliform mandibles and maxillae, which interlock to form the food and salivary canals. The stylet bundle proximal to the labium forms a large loop within a membranous crumena. When fully retracted the coiled stylets are under tension. Stylet extension generates increasing tension so that when retracted the stylets readily recoil within the crumena. Penetration of leaf tissues by the stylet bundle is dependent on the interaction between stylet muscles, opening and closing of the labial clamp, the barbed stylet tips, and the ventral position of the labium.Proximal to the crumena the paired stylets separate and diverge at the entrance of the precibarium, which is formed by the interlocking of the epi-and hypopharynges. There are 18 sensory structures in the precibarium, as well as a precibarial valve. These structures appear to be homologous to similar structures observed previously in aphids and leafhoppers. The morphology and the location of the precibarial sensilla suggest that, like the precibarial sensory organs of aphids and leafhoppers, they are gustatory and probably mediate acceptance or rejection of plant fluids, thus playing a major role in locating tissues for feeding.
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  • 51
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    Journal of Morphology 189 (1986), S. 131-143 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In seven species of lungless salamanders, family Plethodontidae, ranging from medium to very small in body size and from small to very large in cell size, the morphology of the eye and the retina were investigated. Haller's rule was only partially corroborated. While the smallest species had the relatively largest eyes, the largest two species, having the largest cells, showed the third and fourth largest eyes of the series. An effect of cell size was also found with regard to eye morphology. Small species with small cells as well as large species with large cells had relatively small retinae and relatively large lenses. In contrast, small eyes with relatively large cells had absolutely and relatively large retinae and relatively small lenses.The retinae of all investigated plethodontids showed a morphology typical for land vertebrates with two fiber and three nuclear layers. Rods, cones and double cones could clearly be distinguished. A fovea or area centralis was not found. Retina ganglion cell and photoreceptor counts show that the number of these elements was lower than in salamandrids. However, determination of the resolution power of miniaturized eyes based on morphological and behavioral data shows that this does not seem to constitute a functional disadvantage. The morphological and functional properties and constraints of eyes of miniaturized salamanders are discussed.
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  • 52
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    Journal of Morphology 189 (1986), S. 189-197 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types. Nuclei in the first type have highly dispersed chromatin, creating a spongy appearance, whereas in the second type the chromatin is irregularly clumped. Both types of cells are closely associated with processes of radial ependymal glia cells, which perhaps orient their migratory pathways. Cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer. Possibly these cells account for the neuronal increase that takes place in the granular layer during postnatal life. Cells with chromatin clumps are very scarce; ultrastructurally they resemble immature reptilian astroglia cells.
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  • 53
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    Journal of Morphology 188 (1986), S. 335-346 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The medulla of renculi from kidneys of Ringed seals (Phoca hispida) is completely enclosed by cortex except at the hilum. Within the renculus, the fibromuscular coat of the calyx separates from the transitional epithelium at the level of the corticomedullary junction, where the intrarencular arteries also diverge into the parenchyma. Flat ribbons of this stromal tissue form an arborized framework near the medullary side of the intrarencular arteries and the larger of the arcuate arteries derived from them. The ribbons, which are clearly distinct from periarterial connective tissue, are composed of coarse collagenous fibers, elastic fibers, and smooth muscle cells, all oriented in the direction of the long axes of the ribbons, and myofibroblasts. The proportion of smooth muscle cells decreases and that of myofibroblasts increases with increasing distance from the calyx. At the base of the medullary pyramid, the elements of the framework diminish in width and ultimately blend with the surrounding interstitial tissue. The stromal framework, or basket, is homologous with the Sporta perimedullaris musculosa of cetacean kidneys.
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  • 54
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    Journal of Morphology 188 (1986), S. 347-361 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphological comparison was made of the green livers of male and female lampreys (Petromyzon marinus L.) collected during the upstream (prespawning) migration. Light and electron microscope histochemistry for iron, and both thin sections and freeze-fracture replicas in the electron microscope, revealed some sexual dimorphism in these livers. Ferric iron is much more abundant in the liver of females and is present in the cytoplasmic matrix, in dense bodies, and in vacuoles of hepatocytes. The numerous vacuoles of females may be the deposition site of biliverdin and other bile components that would account for the darker green coloration of the liver compared to males. Hepatocytes in females are also characterized by prominent rough endoplasmic reticulum and Golgi apparatus that reflect the involvement of the cells in vitellogenesis. The presence of numerous lipid droplets in the hepatocytes of males indicates that the liver is an important storage site for fat. The lipid droplets are associated with electron-dense deposits of unknown nature. Large gap junctions typify the parenchymal cells of both male and female livers. Perisinusoidal and sinusoidal cells are similar to those in the nonparenchymal region in other vertebrate livers, namely, endothelial and Kupffer cells, lipocytes (Ito), and some granulated cells. The relationship of lipocytes to fibrous tissue and fibrogenesis is discussed.
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  • 55
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    Journal of Morphology 189 (1986), S. 17-24 
    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 hemocytes and nephrocytes in Argas (Persicargas) arboreus is described and compared with that of similar cells in other tick species and insects. The hemocytes are of three types: prohemocytes, with a relatively undifferentiated cytoplasm lacking granular inclusions and probably serving as progenitors of the other hemolymph cell types; plasmatocytes, containing abundant mitochondria, cisternae of rough endoplasmic reticulum (RER), and free ribosomes, as well as some small granular inclusions; granulocytes, the predominant cell type in the hemolymph, containing numerous granules of variable electron density and maturity, and pseudopodia-like processes on the cell surface. Plasmatocytes and granulocytes are phagocytic and possibly also have other functions in the tick body. Cells with intermediate features appear to be in a stage of transition from plasmatocyte to granulocyte.Nephrocytes contain vacuoles enclosing fibrillar material, some electrondense granules, and moderate amounts of the active organelles - mitochondria, RER, and ribosomes. The nephrocyte is surrounded by a basal lamina and its plasma membrane infolds to form many deep invaginations coated by a fine fibrillar material. Openings to these invaginations are closed by membranous diaphragms. Coated tubular elements connect the surface invaginations with large coated vesicles, which appear to be specialized for internalization of proteins from the hemolymph. The dense granules may represent an advanced stage of condensation of ingested protein and thus may be lysosomal residual bodies, or they may develop by accumulation of secretory products.
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  • 56
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    Journal of Morphology 189 (1986) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 57
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    Journal of Morphology 189 (1986), S. 121-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study we examined the possible inductive role of the dental papilla from polyphyodont lizard tooth germs. Flank skin sheets of quail ectoderm enzymatically separated from dermal tissue were recombined with lizard tooth papillae and placed on semisolid medium and cultured for 2 days. Subsequently, the recombinants were removed and placed on the chorioallantoic membrane of chick hosts and incubated for 6 days. After this period of 8 days in explant, control tissues differentiated according to their own phenotypes. Lizard dental papilla alone differentiated as fibroblasts. Quail flank skin ectoderm differentiated into epithelial sheets. Intact lizard tooth buds developed into teeth with dentine and incipient enamel. In the best experimental recombinants, advanced and relatively well-constructed teeth were observed, with clear indications of hard tissue deposition in association with quail epithelium. The results show that mesenchyme of the adult lizard dental papilla and embryonic quail ectoderm of heterotopic origin are capable of carrying out the complex sequence of morphogenetic interactions involved in normal odontogenesis.
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  • 58
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    Journal of Morphology 190 (1986), S. 63-71 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sperm development in Ornithodoros (Pavlovskyella) erraticus includes the formation of subsurface cisternae in the primary spermatocytes, which divide meiotically to secondary spermatocytes and ultimately to spermatids. During spermiogenesis the spermatid undergo morphological transformation including polarization of the nucleus and subsurface cisternae, formation of a cisternal tube, and modification of the subsurface cisternae to cellular processes surrounded by cisternal vesicles. Further transformation occurs after spermatids are introduced into the female. The spermatid cisternal tube now invaginates to form an inner cord surrounded by an outer sheath. The invaginated inner cord elongates anteriorly as the outer sheath continues to invaginate posteriorly during spermiogenesis. With further elongation, the spermatid membrane ruptures anteriorly, leaving the inner cord exposed as the outer surface of the maturing sperm. Posteriorly, the original plasma membrane invaginates to form an acrosomal canal which becomes surrounded by an acrosome. The hemispherical anterior end of the mature sperm is covered with rows of projections separated from the remainder of the sperm by a row of fringed processes. Except for the posterior end, the rest of the sperm is covered by longitudinally distributed electron-dense cellular processes and an outer mat of more electron-lucent tubular elements. Mitochondria and bundles of microfibrils are found beneath the cellular processes. Microfibrils are suggested to be the principal contractile organelles responsible for sperm motility. Cellular processes appear to be the main external motile structures, while movements of tubular elements and fringed processes may also contribute to sperm motility.
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  • 59
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    Journal of Morphology 190 (1986) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 60
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    Journal of Morphology 190 (1986), S. 169-189 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Marlins, sailfish, and spearfishes have a heat-producing tissue beneath the brain and adjacent to the eyes. This tissue warms the brain and eyes while the rest of the body remains at water temperature. The heater tissue is derived from the superior rectus eye muscle. Only a portion of this eye muscle contains normal skeletal muscle tissue; the rest consists of the modified muscle tissue that is associated with heat production. The heat-producing portion is supplied with blood through a countercurrent heat exchanger that originates from the carotid artery. The vascular rete prevents the heat being produced by the tissue from being dissipated at the gill. An unusual circulatory supply to the eyes and brain is associated with the presence of the heater tissue in these fishes.
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  • 61
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    Journal of Morphology 190 (1986) 
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  • 62
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    Journal of Morphology 190 (1986), S. 259-270 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The transport of sperm in the cloaca and adjacent regions of the female red-spotted newt was examined. It was found that within 1 min after sperm were introduced into the vent, they progressed in a random pattern past the apertures of the spermatheca (the gladular, sperm storage organ that opens from the anterior roof of the cloaca) forward to the anterior end of the cloaca and on into the posterior regions of the hindgut and bladder. Sperm did not enter the dorsal recess of the cloaca into which the oviducts and ureters open. After 1 day, few sperm remained within the cloaca lumen. Sperm were not transported into the cloacae of artifically inseminated, anesthetized females without prior administration of norepinephrine to their cloacal mounds. Treatment of the cloacal mounds of naturally inseminated females with an antagonist of neuromuscular transmission (lidocaine) decreased the numbers of sperm in the anterior cloaca relative to those of saline-injected control specimens. Neither dead newt sperm nor live rabbit sperm entered the spermatheca. Rabbit sperm, however, entered the oviduct. It is argued that passive and active mechanisms of sperm transport work in concert. Contractions of smooth muscle, which may be initiated during courtship, probably serve to draw sperm passively into the cloaca and up to and beyond the apertures of spermathecal tubules, but sperm, once in the vicinity of those apertures, probably swim actively into them.
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  • 63
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    Journal of Morphology 190 (1986), S. 319-324 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We recently described basal intracytoplasmic tubules that arise from the basal plasma membrane of rat retinal pigment epithelial cells (RPE). They are a previously undescribed ultrastructural specialization of the basal plasma membrane in addition to the well-known basal folds. This report describes similar tubules in the RPE cells of the rabbit, hamster, and kitten. As in the rat, the tubules in the hamster and kitten ramify singly through the basal cytoplasm and bear no special relationship to any other organelle. In the rabbit, however, stacks of closely apposed tubules frequently abut the large lipid droplets in their RPE cells. Although the function of the tubules is unknown, their occurrence in several different mammals suggests they are involved in the function of RPE cells in general.
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  • 64
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    Journal of Morphology 190 (1986) 
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  • 65
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    Journal of Morphology 190 (1986), S. 335-347 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The keratose demosponge, Dysidea etheria, secretes a skeletal network of interconnecting spongin fibers and incorporates sand grains and other foreign particles into the fibers. Previous studies showed that foreign particles enhanced fiber growth and increased the stiffness of skeletal fibers. The present study uses light and electron microscopy to study the mechanism of particle incorporation. These histological observations show that particles become engulfed into thickened regions of the mesohyl of the dermal membrane, whereupon ameboid cells contact particles and secrete an electron dense layer of extracellular material onto the particle surface. Within several days, particles are moved towards primary skeletal fibers located at cone-shaped protuberances on the sponge surface called conules. Particles accumulate at conules and are consolidated by secretion of spongin at the growing fiber apices. The observations suggest that coordinated migration of groups of mesohyl cells control particle transport to conules and that patterns of cell migration are associated with the structural organization of the dermal membrane. Particle transport may be homologous and analogous to spicule transport in other demosponges.
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  • 66
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    Journal of Morphology 190 (1986), S. 25-37 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fossil and extant dipnoans form a well-defined group of osteichthyans. Tooth plates, a feature in common for extant and the majority of fossil dipnoans, are not found in all dipnoans. Nevertheless primitive dipnoans can be defined by 21 characters of the head skeleton: bone arrangement in the posterior part of the skull roof, relation between supraorbital sensory line and bones, five extrascapulars, ossified (soft in post-Devonian dipnoans) upper lip, lack of premaxilla and maxilla, number and arrangement of bones in cheek region, lack of coronoids, the presence of an adsymphysial plate, ossified (soft in post-Devonian dipnoans) lower lip, relationship of oral and mandibular sensory canal to “infradentaries,” course of neurovascular system in lower jaw, symphysial tubuli in lower jaw, gular-shaped submandibulars, anterior naris at the edge and posterior naris within the mouth, median contact of pterygoids back to jaw articulation, posterior position of parasphenoid (buccohypophysial foramen very anterior in parasphenoid), unpaired “vomer,” autostyly, neurocranial support of posterior dermal skull roof, no isolated hypobranchials, and pharyngobranchials reduced or lacking. These 21 features distinguish the dipnoans from all other sarcopterygians. The Lower Devonian genus Diabolepis, which is said by some authors to have a closer relationship to dipnoans than to any other sarcopterygian, is considered to be inadequately known at present for definite statements about its relationship.
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  • 67
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    Journal of Morphology 190 (1986), S. 133-149 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dermal skeleton of lungfishes is primitively composed of thick cosmine-covered bones and scales. Many Devonian lungfishes exhibit cosmine, while others have denticles of dentine and enameloid that may be arranged in several superposed layers; still others show denticles early in ontogeny superseded by cosmine later. Cosmine is a set of hard and soft tissues that includes bone, dentine, and enameloid, and a vascular and sensory porecanal network. It is the latter that uniquely distinguishes cosmine from other forms of the dermal skeleton and its presence determines the arrangement of the skeletal tissues. I have proposed that the appearance of denticles or cosmine is dependent on the stage of development of the pore-canal system, which may be fully developed as a network or arrested at the free neuromast stage. Other evolutionary trends in the dipnoan dermal skeleton have resulted from repression of the tissue interactions that produce the skeletal tissues.
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  • 68
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    Journal of Morphology 190 (1986), S. 163-179 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Remarkably little is known about the biology of the four Protopterus species, apart from certain detailed studies on their nesting behavior and estivating habits. What information we do have indicates that the species are essentially omnivorous carnivores (especially as predators on molluscs) and that they occupy a wide variety of habitats both lentic and lotic. As obligatory air-breathers able to survive temporary and sometimes extended desiccation of a habitat, lungfishes are often permanent residents in areas from which most actinopterygian fishes are excluded.All four species are able to survive prolonged dry periods. The methods they employ in so doing are varied, and include the secretion of subterranean cocoons, lying-up in water-filled subsurface burrows, or simply burrowing into moist regions of the substrate. Some populations of at least two species live in permanent water and so do not estivate, although they apparently retain the ability to do so.Three of the four species spawn in some form of seemingly constructed or prepared nest. The architecture of these nests shows marked inter- and intraspecific variability and is likely to be determined largely by various environmental factors. All three species show some type of parental care. The breeding biology of the fourth species, P. amphibius, is still unknown.Other aspects of the breeding biology and behavior of Protopterus require a great deal more investigation, as does the biology of the young.
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  • 69
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    Journal of Morphology 190 (1986), S. 217-236 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reviews the cardiorespiratory morphology and physiology of the living lungfishes, in the special context of their highly effective use of both air and water for gas exchange. Particular emphasis is placed on describing those features of the circulatory and respiratory systems that distinguish Neoceratodus from the Lepidosirenidae (Protopterus, Lepidosiren), and which, in turn, distinguish lungfishes from other aquatic vertebrates. Morphological and physiological characters that represent the plesiomorphic condition for the living Dipnoi are indicated (e.g., separate atrial chambers, vertical septum in ventricle, pulmonary veins, conal valves, twisting of bulbus cordis), as are those characters that may be shared derived features of the Lepidosirenidae (e.g., paired lungs, reduced anterior gill arches, well-developed spiral valve in conus). Morphological and physiological comparisons and contrasts with tetrapods are made to elucidate systematic relationships of the Dipnoi with other vertebrates.
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  • 70
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    Journal of Morphology 190 (1986), S. 299-303 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 71
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    Journal of Morphology 190 (1986), S. 277-297 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The phylogenetic affinity of lungfishes has been disputed since their discovery, and they have variously been considered the sister group of actinistians, the sister group of amphibians, or equally related to actinopterygians and crossopterygians. Previous discussions of these hypotheses have considered neural characters, but there has been no general survey of the nervous systems of sarcopterygians that examines the bearing of neural characters on these hypotheses in the context of a cladistic analysis. Such a survey of representatives of all living sarcopterygian groups reveals at least twenty-three characters that are possible apomorphies at some hierarchical level among sarcopterygians. Neural synapomorphies corroborate the phylogenetic hypotheses that actinistians, amphibians, and dipnoans are each monophyletic taxa. The hypothesis that Latimeria is the sister group of amphibians is the least corroborated, as only a single possible synapomorphy, presence of cervical and lumbar enlargements of the spinal cord, supports this hypothesis. The hypothesis that lungfishes are the sister group of amphibians is supported by two possible synapomorphies: loss of a saccus vasculosus and the presence of neurocranial endolymphatic sacs. The hypothesis that actinistians are the sister group of lungfishes is the most corroborated, based on five possible synapomorphies: presence of a superficial isthmal nucleus, a laminated dorsal thalamus with marked protrusion into the third ventricle, olfactory peduncles, evaginated cerebral hemispheres with pronounced septum ependymale, and electroreceptive rostral organs. However, all five characters may be plesiomorphic for bony fishes. The nervous systems of Latimeria and Neoceratodus are very similar to each other, as are the nervous systems of lepidosirenid lungfishes, caecilians, and salamanders. If Neoceratodus is the most plesiomorphic species of living lungfishes, then lepidosirenid apomorphies may have arisen by paedomorphosis. Our inability to examine the neural characters of a relevant outgroup (rhipidistians) may result in many sarcopterygian plesiomorphic characters being interpreted as apomorphic characters, due to the wide distribution of paedomorphic characters among living sarcopterygians and their possible resemblance to plesiomorphic characters present in living outgroups that can be examined.
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  • 72
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    Journal of Morphology 187 (1986), S. 129-142 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cnemidophorus uniparens is a parthenogenetic unisexual species of lizard in which each individual develops as a female, making it a unique animal model for the study of sexual differentiation. In one study, administration of exogenous testosterone before and/or after hatching influenced the development of the gonads, the accessory reproductive ducts, the renal sex segment of the mesonephric kidney, and the femoral glands, a secondary sex character. Testosterone treatment also affected the cross-sectional area of the gonad and the proportions of cortical and medullary tissues present in the developing gonad. The oviducts and femoral glands of testosterone-treated individuals were hypertrophied; the collecting tubules of the kidney of these animals contained granules, an androgen-dependent, sexually dimorphic character in squamate reptiles. In another study, testosterone, dihydrotestosterone, or estradiol were administered to C. uniparens embryos. No treatment effects on gonadal development were detected on the day of hatching. However, estradiol, but not testosterone and dihydrotestosterone, stimulated development of the oviducts. Taken together these studies suggest that androgen aromatization may play a role in sexual differentiation in lizards.
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  • 73
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    Journal of Morphology 187 (1986), S. 173-179 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We compared the proportions of mammalian-type and reptilian-type nephrons in the kidneys of two species of passerine birds. The desert house sparrow (Passer domesticus) is relatively well adapted for water conservation, whereas the white-crowned sparrow (Zonotrichia leucophrys) is more mesic adapted. The two species do not differ in body mass, but the kidneys of P. domesticus are significantly smaller than those of Z. leucophrys. Associated with its smaller size, the house sparrow kidney has significantly fewer glomeruli (35,700 per kidney) than does the white-crowned sparrow kidney (53,000 per kidney). The medullary cones, which contain the loops of Henle of the mammalian-type nephrons, are significantly longer in house sparrows than in white-crowned sparrows (2.2 vs. 1.9 mm). The number of medullary cones, the number of nephrons per medullary cone, and, hence, the number of mammalian-type nephrons do not differ between the two species. The smaller number of nephrons in the kidney of the house sparrow therefore represents a smaller number of reptilian-type nephrons. Desert house sparrows have 18% mammalian-type nephrons, whereas white-crowned sparrows have 10% mammaliantype nephrons. The relative reduction of reptilian-type nephrons in P. domesticus may reduce the flow of dilute urine through the collecting ducts, thereby permitting a greater concentration gradient to be established along the length of the medullary cones.
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  • 74
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    Journal of Morphology 187 (1986), S. 201-217 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The surface morphology of the basilar recess and papilla was examined in 14 species of newts and salamanders selected from the five families of urodeles (Ambystomatidae, Salamandridae, Hynobiidae, Cryptobranchidae, and Amphiumidae) known to have this end-organ. In this sampling, the general organization of basilar structures is essentially similar across species investigated. The recess forms a tubular diverticulum of the proximal part of the lagena. One wall of the recess is associated with a diverticulum of the intracapsular periotic sac, and an adjacent wall is occupied by the basilar papilla. The papilla contained from as few as five hair cells in specimens of Taricha torosa to over 200 hair cells in Cryptobranchus allegheniensis. In most species, the papilla showed a morphological continuum between tall centrally or distally placed ciliary bundles and short ciliary bundles near the papillar margins. In certain species examined, tall bundles had kinocilia with swellings near their tips. Most forms showed a tendency to have groups of ciliary bundles morphologically polarized either toward or away from the saccule. In Cryptobranchus and Dicamptodon, many bundles had a random orientation. The gross and fine structural features of the basilar complex are compared in urodeles and anurans, and “generalized” features for the amphibian basilar complex are suggested. The basilar complex of Cryptobranchus is interpreted as being most generalized, representing a structural form from which most features of the basilar complex in other urodeles and anurans can be derived.
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  • 75
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    Journal of Morphology 187 (1986), S. 261-287 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology and function of the tongue and hyoid apparatus in Varanus were examined by anatomical and experimental techniques. Morphological features unique to Varanus include a highly protrusible tongue that has lost a roughened dorsal surface, an exceptionally strong and mobile hyobranchial apparatus, a well-defined joint between the ceratohyal and anterior process, and a series of distinct muscles inserting at the anterior hyobranchial region. Varanus is also unusual among lizards in a number of feeding behaviors; it ingests prey entirely by inertial feeding, as the tongue does not participate in food transport. Further specializations include an increased reliance on hyobranchial movements in drinking and pharyngeal packing and compression. The long, narrow tongue is most likely related to the mechanics of tongue protrusion; the increased amount, strength, and complexity of hyobranchial movement is related to the fact that the hyobranchium in Varanus replaces the tongue in many functions. Previous hypotheses for the origin of these adaptations are discussed, and the difficulties of attributing these specializations to any specific scenario of adaptation or constraint are emphasized.
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  • 76
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    Journal of Morphology 188 (1986), S. 167-178 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Devil rays (Mobulidae) have large brains that rest in a voluminous chondrocranium almost completely filled by a rete mirabile cranica (RMC). The RMC is a massive arterial network grossly divisible into a “caudal RMC” supplying blood to the brain, and an expanded, more complex “precerebral RMC” nested within the large cranial cavity rostral to the telencephalon.Both the caudal and precerebral retia originate from the posterior portion of the profundae cerebri arteries, which lie ventral to the brain and form the sides of a vascular triangle, the base of which is anterior and formed by the joining of the internal carotids; the vertex is posterior and median, corresponding to the anterior extreme of the spinalis impar artery. Vessels of the caudal RMC branch posteriorly from the profundae cerebri and course over and into the brain. Vessels branching more anteriorly course rostrally to form the precerebral RMC, which takes the shape of the cranial cavity and completely envelops the olfactory peduncles. Large retial arteries (1-mm diameter) branch and taper to about 50-150 μm, forming a system of small arteries or arterioles. Many give rise to a mesh of tertiary vessels (precapillary arterioles or capillaries, ca. 20-50 μm in diameter), which, along with arterioles, are embedded in the adventitia of these arteries, with which they communicate by numerous anastomoses. Although the function of the RMC remains enigmatic, its complexity and fine structure are suggestive, and hypotheses of its role are discussed.
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  • 77
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    Journal of Morphology 188 (1986), S. 203-224 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning and transmission electron microscopy were used to examine the morphology of the perianal processes (trophotaeniae) of goodeid embryos (Girardinichthys viviparus) at two stages of gestation. The epithelial surface of trophotaeniae is composed of two cell types, one of which shows distinct features associated with absorptive activity. Such cells are characterized by microvilli, abundant mitochondria, and an agranular tubulolamellar network. Micropinocytosis at the apical surface is relatively rare. The brush border membranes contain high levels of alkaline phosphatase. The cells of the second type are the minor component of the trophotaenial epithelium. Their surface is distinct, due to the presence of microridges rather than microvilli. The reticulate arrangement of the cells gives rise to intercellular spaces which occasionally are very large. These interstices are populated with leukocytes. The histological appearance of these sections indicates that this tissue is involved in gas exchange. Embryos at very early stages of development possess similar epithelia which are differentiated to a lesser extent. The connective tissue in some parts of the processes shows structural modifications. It is densely packed with numerous leukocytes occupying the spaces between the cytyoplasmic ramifications of the stroma cells. Possible roles of the trophotaeniae in absorption, respiration, excretion, and the acquisition of immunity are discussed, and it is concluded that the perianal processes of the Goodeidae are more than just trophic embryonic structures.
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  • 78
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    Journal of Morphology 188 (1986), S. 251-255 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The surface areas of the tracheal and cuticular systems of Peripatus acacioi individuals of different body weights were determined by morphometric analysis. The results demonstrate that both surfaces increase with body weight, although the observed increase in the surface area of the tracheal system appears to be at a greater rate. The slopes of the two regression lines obtained are statistically different. It is therefore suggested that the preferential route for water loss in P. acacioi is related to the size of the animals, i.e., smaller onychophorans would lose water mainly through the cuticle, while larger ones would lose water through the respiratory surfaces.
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  • 79
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    Journal of Morphology 188 (1986), S. 257-271 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The organization of the body cavity lining in selected regions of the juvenile and adult of the interstitial hesionid polychaete Microphthalmus cf. listensis is described. Tissues comprising the body cavity lining in the juvenile consist of somatic and splanchnic circular and longitudinal muscles and undifferentiated cells. Somatic and splanchnic cell layers exhibit epithelial ( = eucoelomate) organization in the pharyngeal region. In the midbody, some undifferentiated cells exhibiting mesenchymal organization persist among the epithelially organized somatic and splanchnic cells, forming a gradation between eucoelomate and acoelomate tissue organizations. A coelomic cavity is absent. Tissues comprising the body cavity lining of the adult consist of somatic and splanchnic circular and longitudinal myocytes and coelenchymal cells. Coelenchymal cells are shown from serial section analysis to be mesenchymal in organization and derived from the somatic peritoneum. A 30-65-nm coelomic cavity lies between the apices of somatic and splanchnic cell layers in the pharyngeal region. In the anterior setigerous segments, the coelom is reduced to a narrow cavity surrounded by coelenchymal cells lying midventrally between the paired ejaculatory ducts. There is a regional obliteration of the splanchnic musculature in the posterior segments so that apices of the coelenchymal cells lie in direct apposition to the basal extracellular matrix of the gut. The coeom is only present middorsally as a 0.7-μm-wide cavity. Although the coelomic cavity is highly reduced in the adult, the body cavity lining still reveals its origin from the epithelial ( = eucoelomate) organization. The findings of this study illustrate possible organizational intermediates in the evolution of the acoelomate from the eucoelomate condition in annelids.
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  • 80
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    Journal of Morphology 188 (1986), S. 315-326 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogenetic sequence of cranial osteogenesis through adulthood is described in samples of newts from completely metamorphosing and partially neotenic populations. Cranial ossification proceeds in the same sequence in both samples. Seven stages of cranial development are described on the basis of conspicuous events that occur during ontogeny. These include four larval stages, metamorphs, efts, and adults. Neotenic adults have skulls that are metamorphosed completely and indistinguishable from the skulls of non-neotenic adults. Neoteny in these newts does not involve the skull and is limited to the postmetamorphic retention of some gill structures and, thus, is termed “limited neoteny.” The evolution of limited neoteny in newts as a correlated response to the inhibition of land-drive behavior is discussed.
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  • 81
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    Journal of Morphology 188 (1986), S. 366-366 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 82
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    Journal of Morphology 189 (1986), S. 1-16 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Idiocranium russeli is among the smallest species of caecilians. The morphology of the skull (e.g., small, widely spaced dermal elements, retention of cartilaginous remnants) and of the posterior vertebrae (incomplete development, retention of a postvertebral notochord) indicate that heterochrony, or change in timing of development, has resulted in the miniaturization of the species. The pattern is apparently a progenetic one, characterized by early offset of development (see Alberch et al., 1979). Other unique features of osteology (e.g., extensive sphenethmoid development) correlate with the burrowing habit of the species and may have arisen to compensate for progenetic effects. Several features of the myology, neurology, and visceral morphology are correlated with miniaturization as well. Reproductive maturity occurs at approximately 75 mm total length; gonads are proportionately small, but other aspects of reproductive morphology are typical of direct-developing caecilians.
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  • 83
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    Journal of Morphology 189 (1986), S. 261-270 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three regions of the byssus of the marine mussel Mytilus edulis L. are distinct in structural organization at the macroscopic and microscopic level and in amino acid composition. The threads that emanate from the stem at the base of the foot are divided into two regions. The proximal, elastic region has a crimped, densely staining cortex enclosing an interior matrix of spiral fibers, and its amino acid composition reflects protein heterogeneity. The more distal, rigid region has a straight, tubular cortex surrounding an inner matrix of linearly arranged bundles of fibrils and has a composition approximating pure collagen. The plaque, or disc-shaped portion, which mediates attachment to various substrates, is distinguished by a surface matrix of collagen-like fibers similar to those of the thread region and anchored on an inner spongy matrix. Compositional evidence exists for a collagenous component, a catechol-rich protein, and at least one other accessory protein in the plaque.
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  • 84
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    Journal of Morphology 189 (1986), S. 295-311 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of spermatophores was studied in seven species of Oribatei. Each spermatophore is composed of a head and a stalk which is attached to the substratum. The spherical head consists of two distinct portions: (1) the sperm package; and (2) the head matrix. Position and structure of the sperm package are described in the different species, as well as the various structures in the head matrix. The sperm package contains sperm embedded in secretory products. The most characteristic feature of the sperm is an electron-dense chromatin body. Mitochondria lie adjacent to it or are partly or completely incorporated into the chromatin body. The cytoplasmic surface of the plasma membrane regularly bears an electron-dense layer; the plasma membrane is covered by a secretory sheath. The spermatophores of the Oribatei are structurally complicated and not uniform. The possible role of the spermatophore's structural elements is discussed and an attempt is made to evaluate characteristic features taxonomically.
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  • 85
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    Journal of Morphology 190 (1986) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 86
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    Journal of Morphology 190 (1986), S. 9-26 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The head kidney and spleen are major sites of haemopoiesis in fish; a secondary center is found in loose connective tissue of the intestine. In this study we determined the nature of gut-associated haemopoietic tissue in the goldfish, Carassius auratus, using light and electron microscopy. This tissue is a loose stroma of reticular cells and fibers vascularized by capillaries, venules, and arterioles. The cellular population includes lymphoblasts, small and medium-sized lymphocytes, plasmocytes, macrophages, and various granulocytes. The most abundant granulocyte is the mast cell, whose large granules stain with Alcian blue and toluidine blue. Heterophils are found in the intestinal connective tissue as well as two other granulocytes: one with ovoid granules having dense parallel lamellae and another with granules containing crystalline inclusions. Immature forms of both granulocytes were also noted. Macrophages containing phagocytosed debris were often located close to the epithelium; they were observed forming clusters with lymphocytes. The epithelium contained a number of migrating leucocytes including lymphocytes and lymphoblasts, macrophages, and heterophils. Although many granulocytes were found in the connective tissue, granulopoiesis does not seem to be a major function. Gut-associated haemopoietic tissue in goldfish resembles diffuse lymphoid tissue and may be involved in intestinal immune responses.
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  • 87
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    Journal of Morphology 189 (1986), S. 145-156 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structural organization of the compound eye of the largest known isopod, Bathynomus giganteus, is described from four specimens maintained in the laboratory for as long as two months. Living specimens have not previously been available for study. The two triangular compounds eyes measure about 18 mm on the dorsal edge and are separated by an interocular distance of 25 mm. They face forward and slightly downward and may have significant overlap in visual fields. Each eye contains about 3,500 ommatidia in animals of body lengths from 22.5 cm to 37.5 cm. The packing of ommatidia is not uniform across the retina, but is nearly hexagonal in the dorsal central region and nearly square in the ventral and lateral periphery.The dioptric elements in each ommatidium consist of a laminar cornea, which is flat externally and convex internally, and a bipartite crystalline cone. Sometimes seven and sometimes eight retinular cells closely appose the proximal tip of the cone and bear the microvilli of the rhabdom. Proximal to the rhabdom the retinular cells form thin pillars near the periphery of the ommatidium, and the central portion along the optic axis at this level is occupied by interstitial cells that contain massive arrays of clear vesicles thought to serve as reflective elements. The arhabdomeral segments of the retinular cells and the interstitial cells rest on a basement membrane. Within each ommatidium the basement membrane has two extensions with cylindrical cores and thin sheets of dense material and collagen-like filaments. These sheets occupy spaces between adjacent interstitial cells up to the level of the rhabdomeral segments of the retinular cells. Arrays of pigment cells with relatively weak light-screening properties separate adjacent ommatidia.Animals were fixed both in light within a week of being brought from depth into daylight, and after 2 months of maintenance in constant darkness following such daylight exposure. In both cases, microvilli of the rhabdom were severely disrupted and the retinular cytoplasm contained numerous multivesicular bodies. Exposure to natural daylight appears to cause irreversible structural damage to the photoreceptors of these animals.
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  • 88
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    Journal of Morphology 189 (1986), S. 183-188 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Birds and many reptiles are egg-layers. Birds provide calcium for the formation of eggshells by resorbing medullary bone, which is laid down before ovulation. Turtles do not possess this mechanism and resorb structural bone to form eggshells. Femora from three groups of alligators (egg-laying females; quiescent, immature, or barren females; and males) were examined to determine if alligators, which are closely related to birds in evolution, resorb structural bone during the formation of eggshells as do turtles. Microradiographs of cross sections from femoral mid-shafts were analyzed for porosity, and the robusticity index of each femur was determined. Scanning electron micrographs of anorganic endosteal and periosteal femoral surfaces were analyzed to determine numbers of entrances of vascular canals, numbers of lacunae of osteoblasts, and types of femoral surfaces. Femora from egg-laying females were significantly less robust than those of other females or males, and sections of bone from the egg-layers were significantly more porous than those of the other groups. Scanning electron microscopy of anorganic femoral endosteal surfaces from egg-laying females revealed significantly more resorption areas when compared with males or non egg-laying females. Periosteal surfaces from egg-layers had significantly more resting and less bone-forming surface than those from the other groups. Results indicated that apposition of periosteal bone may have been reduced in egg-layers and that egg-laying alligators, like turtles, resorb endosteal structural bone, which may be used as a source of calcium for the formation of eggshells.
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  • 89
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    Journal of Morphology 189 (1986), S. 215-224 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphological, mineralogical, and chemical investigations were undertaken to determine the structure and composition of the cell walls of the comb in the nest of Vespa orientalis, Paravespula germanica, and Vespacrabro. Nests of V. orientalis were from three sites having different soil types, namely, Khamra soil, Gramosol soil, and organically rich soil from the city dump in Tel Aviv. Nests of P. germanica were from areas rich in organic matter, and those of V. crabro, shipped from Austria, were similarly comprised of organic matter. Structure and composition of cell walls in the three species differed; furthermore, grain size in the combs differed from that of particles in the surrounding soil.
    Additional Material: 7 Ill.
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  • 90
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 225-247 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparison of the ampullae of Lorenzini among 40 species of skates (Rajoidei) demonstrates a close relationship between inferred electroreceptive capabilities and feeding mechanisms. Three general lines of morphological modifications are noted. (1) Whereas the majority of ampullary pores are located on the ventral surface of the dorsoventrally flattened body, the relative proportion of ventral pores is significantly lower on species inhabiting aphotic waters. (2) The ventral pores on more piscivorous species are distributed over a larger portion of body surface than they are on those species that feed primarily on invertebrates. Ventral pores in this latter group are more noticeably concentrated around the mouth and their densities on the adult are inversely related to the overall mobility of preferred prey species. (3) The size of each ampulla and the number of alveoli associated with it are directly related to the habitat depth occupied by each species. Shallow-water species have smaller ampullae with fewer alveoli than deeper-dwelling (〉 1,000 m) species.The general distribution of ampullary pores on deep dwelling rajoids appears to compensate for reduced visual input, whereas their relative densities are a measure of the system's resolution and reflect major differences in feeding strategies. The increased ampullary size and complexity observed in deep-sea rajoids provides mechanisms to increase both the sensitivity and signal-to-noise ratios.
    Additional Material: 13 Ill.
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  • 91
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 281-293 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Numerous female workers underwent a beginning of sexualization in an experimentally orphaned colony of the Neo-Guinean termite N. princeps (Desneux). This led to the development of intercastes, displaying variable mosaics of worker, nymph, and soldier characteristics. The developmental pathways of these intercastes were studied with the help of multivariate techniques that revealed two main lines, one ending in a new “giant soldier” morph, the other proceeding toward the differentiation of nymphal characters, i.e., wing pads and compound eyes. It is not known whether these individuals might ultimately have become functional. Precocious adults resulting from a shortened nymphal course were also present, and one young replacement queen had already begun laying eggs.
    Additional Material: 8 Ill.
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  • 92
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 313-325 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study addressed the problem of how soft structures maintain approximately the same relative positional relationships during long bone growth. Attachments of the popliteus muscle, semitendinosus tendon, medial collateral knee ligament, and extensor retinaculum were examined histologically in rabbits, aged 2-60 days, to determine the manner in which soft structures attached to long bones during growth. Soft structures inserted principally into fibrous periosteum or perichondrium in the age range studied. However, an extensive collagen fiber framework within the cellular periosteum and perichondrium, present by at least 2 days of age, linked the fibrous periosteum or perichondrium to subjacent bone or cartilage. Maturation of soft tissue-bone interfaces was viewed from two related perspectives. The first stressed temporal patterning of cartilage and bone differentiation. The second emphasized incorporation of attachments of soft structures into bone and cartilage matrices during growth and remodeling. Differentiation and remodeling of bone and cartilage varied not only with age, but also between regions of attachment of single muscles and ligaments. Insertion regions were characterized by the presence of coarse-fibered periosteal bone and chondroid bone, both morphologically intermediate between fibrocartilage and lamellar bone. These results provide evidence that periosteal attachments, characterizing the soft-tissue bone interface, are a necessary structural prerequisite for compensatory movement and invariance of the relative positions of muscles, tendons, and ligaments during long bone growth.
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  • 93
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    Journal of Morphology 190 (1986), S. 27-41 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: There are two types of cheek pouches in extant rodents. Internal cheek pouches are evaginations of the oral cavity deep to M. platysma and M. sphincter colli profundus, and have evolved independently in some species of the superfamilies Sciuroidea and Muroidea. External, furlined cheek pouches open lateral to and separate from the oral cavity, (also deep to M. platysma and M. sphincter colli profundus), and occur in all species of the families Geomyidae and Heteromyidae. The presence of external, furlined cheek pouches is a synapomorphy for the superfamily Geomyoidea.The posterior retractor muscle of the pouch is derived from facial musculature in sciurids, from trapezius musculature in cricetids, and from both facial and trapezius muscle groups in the Geomyoidea. Differences also exist in the musculature associated with the pouch opening. In the Sciuridae and Cricetidae, the M. buccinatorius muscle group acts as a sphincter to control the size of the pouch opening. In the Geomyoidea, the size of the opening is controlled by the M. orbicularis sacculi in concert with a slip of the M. Platysma myoides.Thin sections and scanning electron micrographs of the pouch tissue reveal the presence of dermal papillae in Phodopus sungorus but not in a close relative, Mesocricetus auratus. All members of the subfamily Cricetinae have a peninsula of highly folded tissue projecting anteriorly from the posteromedial pouch wall. This folding allows for expansion of the pouch walls when food is stored in the pouch.
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  • 94
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    Journal of Morphology 190 (1986), S. 73-79 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The allometric relations of diameter and length of humerus, ulna, femur, and tibia of 108 specimens, from 63 different breeds of dogs and 12 specimens of wolves, were calculated by means of model II of regression or major axis method. Only for the tibia were the values of wolves included in the cluster formed for dog breeds. Consequently, separate lines of regression were calculated for the other bones.Results agree in general with the exponents predicted by the theory of geometric similarity; however, the slope obtained for femur (0.865) differed significantly from this. Morphology of the long bones of the legs does not differentiate dogs and wolves; this probably reflects secondary convergence among wolves with relatively modern breeds of dogs.
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  • 95
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    Journal of Morphology 190 (1986), S. 93-107 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the circulatory organs of Leiobunum limbatum, Mitopus morio, and Rilaena triangularis (Arachnida: Opiliones) has been investigated. We studied the organization of the heart, the myocardial contractile elements, its tubular system, organelles, and cell-junctions. The epicardium exhibits a large number of longitudinally arranged microtubules and is attached to the myocardium by special membrane complexes. Because of these structures, the epicardium is interpreted as the elastic antagonist to the heart muscle. At both ends of the heart the epicardium continues into a nonbranching aorta. Consequently the ultrastructure of the aortal wall, containing numerous microtubules, is similar to the ultrastructure of the epicardium. At the posterior end of the heart is a muscular slit-valve, while at the anterior end is a lobe-valve that lacks contractile elements. The heart is innervated by a dorsal ganglion. It covers the entire length of the heart and contains neural and glial cells. Two different types of neurosecretory granules and both electron-dense and electron-lucent synaptic vesicles are described.
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  • 96
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    Journal of Morphology 190 (1986), S. 121-167 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Females of Hebrus pusillus and H. ruficeps have two ovaries of five telotrophic ovarioles each, two lateral oviducts, a common an intricate sperm storage and delivery system, the gynatrial complex, and a short, tubular ovipositor. The skeletomusculature of this system is fully described in both species and its functions (summarized in Figs. 55-66) reconstructed from study of living bugs, dissections, whole mounts and serial sections.To mate, a male H. pusillus jumps on the back of a female, induces her to lower her ovipositor, and, within 12 min (at 18-24°C), introduces the endosoma of his phallus up its shaft and fills his seminal duct with sperm. The female draws this into her gynatrial sac at the end of copulation and transfers it into her spermatheca in about 30 min (both sperm and spermatheca are longer than the female's body). A single, large egg passes from an ovariole into the vagina where its apex is temporarily lodged in a fertilization chamber. Spermatozoa are drawn from or swim out of the spermatheca into a grooved fecundation canal in the roof of the vagina and forward to the micropyle of the egg. After fertilization, the egg enters the base of the ovipositor and is deposited.The gynatrial complex of female, semiaquatic bugs probably evolved to accommodate the fertilization of the proportionately larger eggs of a lineage of bugs ancestral to Gerromorpha that was being selected for small body size and was then modified to increase the role of the female in controlling fertilization of eggs.
    Additional Material: 67 Ill.
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  • 97
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    Journal of Morphology 190 (1986), S. 201-213 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy and histology of the white sturgeon digestive system is described for the adult stage and the first 36 days of posthatch development. Although the adult gut is only 87% of standard length, absorptive surface area is effectively increased by the thick mucosa of the postgastric gut and by lengthening of the gut due to the presence of the spiral valve and the pyloric caecum. Modifications of the gut of this species, relative to that of other chondrosteans, are consistent with its durophagous feeding habits. The arrangement of the intestinal epithelium differs from that of most fish and is organized so that absorptive activities occur in deeper regions, whereas goblet cells dominate the lumenally exposed epithelium. The gut develops from an intraembryonic yolk endoderm. At conclusion of the endogenous nutrition phase the alimentary canal is similar to the adult form and a functional gastric region is present. The anatomical characteristics coincide with physiological data collected throughout the life history of this species.
    Additional Material: 11 Ill.
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  • 98
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    Journal of Morphology 190 (1986), S. 243-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three types of neuronal perikaryal profiles were identified in the dorsal column nucleus and the nucleus of Bischoff of the python (Python reticulatus). Type I neuronal profiles are large (diameters 12-20 μm) with a deeply indented uncleus. The cisterns of rough endoplasmic reticulum (rER) are mostly randomly dispersed. Axosomatic synapses are few. Type II neuronal profiles (9-11 μm) have a smooth, round, or slightly oval nucleus. Several small stacks of rER are present. Type III neuronal profiles (8-10 μm) have little cytoplasm. The nuclear margin is irregular but not deeply infolded. The rER usually consists of a single long perinuclear ribosome-studded cistern. Two types of astrocytic profiles have been identified. Both types contain abundant filaments. Type I astrocytes are large cells, and the nucleus is very irregular in shape. Type II astrocytes are smaller and are found among the myelinated axons in the dorsal funiculus. Two classes of axon terminals have been identified. One class contains round synaptic vesicles (R profiles) and the other flattened vesicles (F profiles). Some R profiles are small (SR profiles), others are large (LR profiles). Some R profiles also contain a few large, dense-cored vesicles. The R and F profiles establish axodendritic and axoaxonal synapses, some of which are located in the synaptic glomeruli and others in the extraglomerular neuropil. In most of the axoaxonal synapses, the presynaptic element is an F profile and the post synaptic element an LR profile. Occasionally, LR profiles are presynaptic to F profiles.The findings in the python are compared with those of the dorsal column nuclei of the rat, cat, and monkey.
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  • 99
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 285-296 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Atretic follicles of the ovary of the Indian pied myna (Sturnus contra contra) were studied in birds collected each month throughout the year. Histological examination included histochemical techniques for 3β-hydroxy-steroid dehydrogenase (3β-HSDH) and for lipids. Atretic follicles were mainly of two types: nonbursting (lipoidal and cystic) and bursting (Types I-VI). Nonbursting atresia was observed in the smaller follicles (〈 500 μm in diameter), whereas larger follicles (〉 500 μm in diameter, viz., small developing, large developing, and yolky follicles) showed exclusively a bursting type of atresia. Sudanophilic lipid was found in both types (lipoidal and cystic) of nonbursting atresia, but was present only in early stages of bursting atresia. Activity of 3β-HSDH was absent in nonbursting atresia, but present in early stage of bursting atresia. Nonbursting atresia was common throughout the year and higher in frequency than the bursting type. Bursting atresia was common during March through May and attained its peak level during the nesting cycle.
    Additional Material: 15 Ill.
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  • 100
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 307-318 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exocytosis of residual bodies by choanocytes, archeocytes and endopinacocytes lining the aquiferous system of Ephydatia fluviatilis has been demonstrated using calibrated latex beads and Escherichia coli as tracers. In passing into the mesohyl or the lumen of the exhalant aquiferous canals, beads, and altered bacteria were enveloped by the plasma membrane of the cell containing them. The membrane constricted at a neck region to form extruding vacuoles. This process appeared first in choanocytes and later in other cell types. The occurrence of these buds increased with the length of incubation time, as did the number of particles they contained. Acid phosphatase activity was frequently associated with the particles budding from the cell membrane, confirming that this process followed digestive activity.Membranous vacuoles were recovered from the external medium and observed by TEM and those adhering to the substratum were seen by SEM. These observations proved that vacuoles were released from the sponges. This membrane-consuming mechanism of exoctyosis implies intense membrane replacement in the digestive cells of the sponge.
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