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  • 1985-1989  (1,389)
  • 1985  (1,389)
  • Life and Medical Sciences  (1,389)
  • Cell & Developmental Biology  (1,154)
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Years
  • 1985-1989  (1,389)
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 183 (1985), S. 293-299 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Use of the term “trophoblast” in descriptions of therian (marsupial and eutherian) mammals has caused confusion because of misinterpretations of blastular homologies and because of imprecise application in functional versus ontogenetic-phylogenetic senses. Marsupials follow the plan of early development characteristic of noneutheian amniotes. Eutherians, in contrast, are unique in the early determination of presumptive embryonic versus extraembryonic cells through formation of inner cell mass versus trophoblastic (or trophectodermal) tissues, respectively. No cellular unit of the eutherian blastula is recognizable unequivocally as the homologue of a specific part of the protodermal marsupial blastula; progressive deletion of innovative but phylogenetically older ontogenetic steps probably figured importantly in the evolution of eutherian early embryogenesis. Because of marked differences in mode of formation and in cellular fates, homology of the blastocoel between marsupials and eutherians is questioned. It is suggested that use of the term “trophoblast” (1) be restricted to eutherians in discussions of ontogenesis or phylogenesis, and (2) be deemphasized in the functional sense (i.e., fetal-maternal exchanges) for marsupials, in favor of the more appropriate tissue terms of “choriovitelline” and “chorioallantoic” membranes. Integral to the origin of the eutherian style of embryogenesis was the evolution during Cretaceous time of neomorphic, extraembryonic tissues (i.e., trophoblast) having physiological properties that allowed the unique combination of (1) intimate apposition of fetal and maternal tissues and circulatory systems, along with (2) sustained, active morphogenesis. Marsupials have not achieved such a combination.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 1-22 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Males of Euphydryas editha (Lepidoptera: Nymphalidae) need their antennae to mate successfully, but females do not. Antennal structure was investigated in the hope of explaining this functional dimorphism, which is opposite to that in other butterflies (e.g., Myers, '68; Grula and Taylor, '80). No external differences between the sexes were observed with electron microscopy. There are four types of antennal sensilla: the spine, which acts mainly as a mechanoreceptor, shallow dish hairs and hidden hairs, which are chemoreceptors, and a whiplike sensillum of uncertain function. The internal morphology of male and female antennae differs in several respects which may relate to functional differences. The mating systems of butterflies are discussed briefly to explain our results and those of others.
    Additional Material: 14 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 23-31 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lifelike models of the oscillating legs treated as three-segment systems show the course of kinetic and potential energy over the locomotor cycle for a cheetah, pronghorn, jackrabbit, and elephant running at speeds approaching their maxima. The models can be adjusted to eliminate differences among the animals in time intervals, mass or length of limb, and joint angles. This facilitates analysis of the influence on total energy of each of these variables and of the distribution of mass among leg segments. Fast-cycling legs of the carnivore type have significantly more energy than those of the hoofed type. This may contribute to the lesser endurance that is usual for carnivores that hunt using a high-speed dash.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 33-40 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The size and microscopic structure of the spleen of the migratory pied flycatcher (Ficedula hypoleuca) show marked changes during the reproductive cycle. Upon the spring return to their northern breeding sites, the birds have a small spleen with little lymphoid activity and a poorly developed red pulp. During the breeding period the volume of red and white pulp increases, the number and distinctness of lymphoid follicles (germinal centres) in the white pulp increase, and groups of cells with intensely basophilic cytoplasm, probably B cells (plasma cells), appear. The findings suggest that the immune system of the adult pied flycatcher is activated during periods when it is bound to the nest.Young flycatchers beginning their autumn migration also show a marked increase of lymphoid activity in the spleen.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 61-73 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Innervation of the early pelvic fin bud in the trout embryo involves four nerves. Electron microscopy discloses axons in the mesodermal mesenchyme and in the epidermis of the bud as early as stage I of the development of the pelvic fins. Sensory axons alone penetrate the epidermis. Unmyelinated axons invade the pelvic fin territory before the bud is obvious on the abdomen. Schwann cells occur in the vicinity of the ventral edge of the myotomes and later in the core of the bud and in subepidermal regions. Consequently, the nerve fibers are present early in the development of the pelvic fin bud of the trout embryo. Although the role of these axons is unknown, it is speculated that they play a role in development. Our results are discussed in the light of data available in the literature dealing with the development of tetrapod appendages.
    Additional Material: 17 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 51-59 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphological and cytometric analysis of the adult fat body cells and oenocytes was made on sections of abdomens from immature, mature and senescent Drosophila melanogaster of both sexes. There are about 18,000 fat body cells in abdomens of female and mature male flies. Immature and senescent males have about 12,000 and 15,000 cells, respectively. The size of the cells is almost the same for immature flies of both sexes and increases about six-fold to approximately 2600μm2, so that mature flies of both sexes have equivalent amounts of fat body tissue. The proportions of lipid, glycogen, and background cytoplasm of fat body cells also remain relatively constant throughout adult life, but dense, proteinaceous granules are observed in cells of senescent flies. The amounts of cellular components change dramatically due to change of cell size with age; the amount of lipid shows the greatest sexual difference with about 2 × more in the females at all stages studied. The oenocytes number about 6,000 in the abdomens of all but immature male flies, which have approximately 4,000. Although the cells of both sexes triple in size to about 700 μm2, the oenocytes of males reach maximum size earlier than those of females. The major features of oenocytes appear to be dense background cytoplasm, putative lipid droplets found only in mature flies, and pigmented granules first seen in the cells of mature flies which accumulate with age to 33% of the cytoplasm. The number of cells and their anticipated capacity for protein synthesis is discussed in relation to the production of yolk protein precursors.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 41-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Upon fertilization, the zebrafish egg undergoes marked physiological and structural changes, one of which involves blastodisc formation. Before fertilization, yolk globules are rounded and the endoplasm extends throughout the oocyte. During blastodisc formation, the yolk globules become angular and the endoplasm is restricted to streamers among the yolk globules. The streamers are oriented in an anterior-posterior axis of the egg. During blastodisc formation the cytoskeleton consists of an extensive array of filamentous structures of variable width in both the cortex as well as within elongate endoplasmic streamers. Although the filamentous components in the cortex and endoplasmic streamers probably include both microfilaments and microtubules, frequently they are somewhat wider than the usual dimensions, and possible reasons for this are suggested. From their arrangement in both the cortex and endoplasm, it seems likely that the components of the cytoskeleton (e.g., microfilaments and microtubules) may provide, through contraction, the major force responsible for the streaming of the endoplasm into the forming blastodisc. It is assumed that the surface tension of the vegetal hemisphere exceeds that of the animal hemisphere, thus forcing, through differential contraction, the endoplasm to flow in the direction of the forming blastodisc. No distinct barrier between the yolk and forming blastodisc was observed. The compressed condition of the larger and many-sided yolk globules could prevent their movement into the blastodisc. Scanning electron microscopy is limited in the resolution with which it can depict the cytoskeleton, but nonetheless it provides useful information about structural interrelationships.
    Additional Material: 12 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 99-100 
    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 184 (1985), S. 111-120 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mature spermatozoon of Admetus pomilio is a spherical cell containing nucleus and tightly coiled flagellum. In early spermatids the Golgi apparatus forms the acrosomal vesicle and at the opposite side the distal centriole gives rise to the axonemal complex of the sperm tail. As the nucleus elongates, chromatin forms twisted filaments and the spermatid nucleus takes on a helical form. Microtubules are juxtaposed with the nucleus envelope, which is separated from a central chromatin mass by an electron lucid region. A long perforatorium, located on the border of the chromatin mass, runs helically in the nucleus from the centriolar region to subacrosomal space. During tail elongation, the anterior part of the axoneme is surrounded by a long, spiral mitochondrial sheath. In the late spermatid, chromatin filaments appear twisted and become aggregated. The nucleus and flagellum undergo further contortions in which the nucleus coils and the flagellum winds up into the body of the cell and coils in a regular fashion. The mitochondrial sheath surrounds about 2/3 of the 9 + 3 axoneme. These features of spermatid ultrastructure resemble those in the primitive Liphistiomorpha.
    Additional Material: 18 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 135-154 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dorsal ventricular ridge is a subcortical structure receiving sensory information from the thalamus in reptiles. In the red-eared turtle, Pseudemys scripta elegans, it contains four cytoarchitectonic areas each characterized by distinct thalamic projections. This is an electron microscopic study of one of these, the dorsal area, which receives its thalamic input from the tectorecipient nucleus rotundus. It contains four concentric zones, internal to the ependymal zone, each of which is distinguished by the distribution of spiny and aspiny neurons.The ependymal zone of dorsal area contains tanycytes whose tails extend into zones 2 and 4. Synapses, usually with asymmetric junctional complexes and round synaptic vesicles, occur on these processes. Zone 1 neurons have fusiform somata and dendrites that parallel the ventricular surface. Their cytoplasm contains rough endoplasmic reticulum located primarily in Nissl bodies, lipofuchsin granules, multivesicular bodies, extensive arrays of Golgi apparatus, and large numbers of mitochondria. Synapses occur mainly on dendritic spines and shafts of zone 1 neurons and less frequently on somata. The majority have round vesicles and asymmetric junctional complexes. In contrast to those in zone 1, neurons in zones 2 and 4 have large amounts of rough endoplasmic reticulum, giving their cytoplasm an electron-dense quality. Synapses occur mainly on spines and shafts of zone 2 and 4 neurons. As in zone 1, the majority have round synaptic vesicles and contain asymmetric junctional complexes. Zones 2 and 4 contain clusters of neurons distributed among isolated neurons. The clusters are larger and less frequent in zone 2. Protoplasmic and fibrous glial processes, axon boutons, dendrites, and axon fascicles surround the neuron clusters. Though less numerous, the same structures also occur inside the clusters. Most synapses inside the clusters have round synaptic vesicles, asymmetric junctional complexes, and occur mainly on spines. Some neurons in clusters have somata whose plasma membranes are in direct apposition. In contrast to dorsal ventricular ridge in snakes, no specialized intercellular contacts were seen between somata in clusters.
    Additional Material: 14 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985) 
    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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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 215-230 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tooth primordia at early stages of mineralization in the sharks Negaprion brevirostris and Triaenodon obesus were examined electron microscopically for evidence of ameloblastic secretion and its relation to calcification of the enamel (enameloid) layer. Ameloblasts are polarized with most of the mitochondria and all of the Golgi dictyosomes localized in the infranuclear end of the cell toward the squamous outer cells of the enamel organ. Endoplasmic reticular membranes and ribosomes are also abundant in this region. Ameloblastic vesicles bud from the Golgi membranes and evidently move through perinuclear and supranuclear zones to accumulate at the apical end of the cell. The vesicles secrete their contents through the apical cell membrane in merocrine fashion and appear to contribute precursor material both for the basal lamina and the enameline matrix. The enamel layer consists of four zones: a juxta-laminar zone containing newly polymerized mineralizing fibrils (tubules); a pre-enamel zone of assembly of matrix constituents; palisadal zones of mineralizing fibrils (tubules); and interpalisadal zones containing granular amorphous matrix, fine unit fibrils, and giant cross-banded fibers with a periodicity of 17.9 nm. It seems probable that amorphous, non-mineralizing fibrillar and mineralizing fibrillar constituents of the matrix are all products of ameloblastic secretion. Odontoblastic processes are tightly embedded in the matrix of the palisadal zones and do not appear to be secretory at the stages investigated. The shark tooth enamel layer is considered homologous with that of other vertebrates with respect to origin of its mineralizing fibrils from the inner dental epithelium. The term enameloid is appropriate to connote the histological distinction that the enamel layer contains odontoblastic processes but should not signify that shark tooth enamel is a modified type of dentine. How amelogenins and/or enamelins secreted by ameloblasts in the shark and other vertebrates are related to nucleation and growth of enamel crystallites is still not known.
    Additional Material: 14 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 231-252 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopy of the pacemaker ganglion of the scorpion heart indicate that it is about 15 mm long and 50 μm in diameter and extends along the dorsal midline of the heart. The largest cell bodies (30-45 μm in diameter) occur in clusters along the length of the ganglion. The ganglion appears to be innervated with fibers from the subesophageal and first three abdominal ganglia.The cardiac ganglion is surrounded by a neurilemma and a membranous sheath. The latter is apparently derived from connective tissue cells seen outside the ganglion. Nerve fibers other than those in the neuropil areas are usually surrounded by membrane and cytoplasm of glial cells. Often there are several layers of glial membrane, forming a loose myelin. The cardiac nerves to the heart muscle are also surrounded by a neurilemma, and the axons are surrounded by glia. The motor nerves contain lucent vesicles 60-100 nm and opaque granules 120-180 nm in diameter.In the cardiac ganglion, some nerve cell bodies have complex invaginations of glial processes forming a peripheral trophospongium. In the neuropil areas, nerve cell processes are often in close apposition. The septilaminar configuration typical of gap junctions is common, with gap distances of 1-4 nm. In tissues stained with lanthanum phosphate during fixation, we found gaps with unstained connections (1-2 nm diameter) between nerve-nerve and glial-nerve cell processes. Annular or double-membrane vesicles in various stages of formation were also seen in some nerve fibers in ganglia stained with lanthanum phosphate.Nerve endings with electron-lucent vesicles 40-60 nm in diameter are abundant in the cardiac ganglion, suggesting that these contain the excitatory transmitter of intrinsic neurons of the ganglion. Less abundant are fibers with membrane-limited opaque granules, circular or oblong in shape and as much as 330 nm in their longest dimension. Also seen were some nerve endings with both vesicles and granules.
    Additional Material: 21 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 253-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The location and arrangement of the pancreatic endocrine tissue in larval and adult Geotria australis (Geotriidae) differ markedly from those exhibited by the comparable stages of Northern Hemisphere lampreys (Petromyzontidae). In larval Geotria australis, the main zones of islet proliferation are located laterally between the oesophagus and the inner edge of the two large intestinal diverticula unique to this species rather than dorsal and ventral to the oesophagus. In adult Geotria australis, the islet follicles are closely packed into a single discrete capsule which could be easily removed surgically, rather than into cranial, intermediate, and caudal cords. The differences in the adult can be related to a lack of involvement of the bile duct in islet formation during metamorphosis. While B cells were found in both larval and adult islet follicles, the PI acidophilic cells and argyrophilic cells, which appeared respectively at stages 3 and 4 in metamorphosis, were present in all adult stages.
    Additional Material: 11 Ill.
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  • 15
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The crinoid arm muscles consist of obliquely striated fibers with striking differences in function and in ultrastructural features. These fibers can be distinguished mainly on the basis of different myofilament arrangements (A- and B-type patterns) and are variously combined at different levels (proximal, intermediate, and distal portions) of the arm. Some rare smooth fibers (C-type) are irregularly distributed in the periphery and in the core of the bundle. The characteristic features of the A- and B-type obliquely striated fibers are (1) a continuous and homogeneous structure of the Z line and (2) a very heterogeneous arrangement of myosin filaments which vary widely in size, number, and distribution from section to section. The significance of such an atypical, obliquely striated muscle may be related to the double skeletal system combination (endoskeleton and hydroskeleton) of the crinoid arms.
    Additional Material: 18 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 89-100 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Eight secretory cell types are identified in the clitellar epithelium of Eisenia foetida, of which five have been described in detail previously (i.e., the large granular, fine granular, metachromatic, orthochromatic, and small granular proteinacecus cells).The remaining three secretory cell types are mucus-producing cells specific to the clitellar epithelium (type 3), cells associated with the chaetal follicles (type 4), and cells that occur exclusively in the tubercula pubertatis (type 5). Type 3 cells secrete a mucus containing neutral and acid mucosubstances. Ultrastructurally, type 3 cells are characterized by membrane-bound globules 0.4 to 3.7 μm in diameter. The contents of the globules have a finely reticulate appearance. The secretion of type 4 cells contains a collagenlike protein and neutral and sulfated acid mucosubstances. Type 4 cell secretory granules are membrane bound and range in diameter from 0.8 to 1.6 μm. They contain large, electron-dense, spheroid cores which are surrounded by parallel orientated microfibrils 14 nm in diameter. Type 5 cells give variable responses to the histochemical techniques used in the present study. An elastinlike protein is detected in about half of the type 5 cells and acid and neutral mucosubstances in the remainder. At the ultrastructural level the secretory granules vary in shape from spheroid to polygonal. Their finely, electron-dense contents exhibit progressive swelling which results in the eventual rupture of the limiting membranes of the granules. The necks of types 3, 4, and 5 cells contain a peripheral ring of microtubles (20 ± 1 nm in diameter).
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 101-114 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paraffin sections of an ontogenetic series of embryos of the viviparous lizard Gerrhonotus coeruleus and the oviparous congener G. multicarinatus reveal that although general features of the development of the chorioallantoic and yolk sac membranes are similar, differences are evident in the distribution of the chorioallantoic membrane in late stage embryos. An acellular shell membrane surrounds the egg throughout gestation in both species although the thickness of this structure is much reduced in G. coeruleus over that of G. multicarinatus. The initial vascular membrane to contact the shell membrane in both species is a trilaminar omphalopleure (choriovitelline membrane) composed of ectoderm, mesoderm of the area vasculosa, and endoderm. This transitory membrane is replaced by the vascularized chorioallantois as the allantois expands to contact the inner surface of the chorion. Prior to the establishment of the chorioallantois at the embryonic pole, a membrane begins to form within the yolk ventral to the sinus terminalis. This membrane, which becomes vascularized, extends across the entire width of the abembryonic region and isolates a mass of yolk ventral to the yolk mass proper. The outer membrane of the yolk pole is a nonvascular bilaminar omphalopleure (chorionic ectoderm and yolk endoderm). In G. multicarinatus the bilaminar omphalopleure is supported internally by the vascularized allantoic membrane, whereas in G. coeruleus the allantois does not extend beyond the margin of the isolated yolk mass and the bilaminar omphalopleure is supported by the vascularized intravitelline membrane. Both the chorioallantoic placenta (uterine epithelium, chorionic ectoderm and mesoderm, and allantoic mesoderm and endoderm) and the yolk sac placenta at the abembryonic pole (uterine epithelium, chorionic ectoderm, and yolk sac endoderm) persist to the end of gestation in G. coeruleus.
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  • 18
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 143-143 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: No Abstracts.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 115-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An ovarian follicle of Drosophila consists of an oocyte, 15 nurse cells, and hundreds of follicular epithelial cells. A freeze-fracture analysis of the surfaces between glutaraldehyde-fixed ovarian cells showed that all three cell types were interconnected by gap junctions. This is the first report of gap junctions between adjacent nurse cells, between nurse cells and oocytes, and between follicle cells and oocytes in Drosophila. Since we did not observe intramembranous particle clumping into crystalline patterns and since structurally different gap junctions occurred at different times in development and at different cell-cell interfaces, it is unlikely that fixation artifacts influenced particle distribution in our experiments. A computer-assisted morphometric analysis showed that the extent, size, and morphology of gap junctions varied with development and that these junctions can cover up to 9% of the cell surfaces. To test the role of gap junctions in follicular maturation, we studied ovaries from flies homozygous for the female sterile mutation fs(2)A17, in which follicles develop normally until yolk deposition commences. During the development of mutant follicles, gap junctions became abnormal before any other morphological aspect of the follicle. These studies show that gap junctions are available to play an important role in coordinating intercellular activities between all three cell types in ovarian follicles of Drosophila.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985) 
    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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  • 21
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 131-142 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the four-eyed fish, Anableps (Atheriniformes, Anablepidae), eggs are fertilized and embryos develop to term within the ovarian follicles. Development is highly matrotrophic. During gestation, the largest term embryo of A. anableps examined had grown to a total length of 51 mm and attained a dry weight of 149 mg. The postfertilization weight increase is 298,000%. The largest term embryo of A. dowi examined had grown to a total length of 77 mm and attained a dry weight of 910 mg. The postfertilization weight increase is 843,000%. Embryonic weight increases result from nutrient transfer across the follicular placenta. This structure is formed by apposition of the maternal follicular epithelium to absorptive surface cells of the embryo's pericardial trophoderm. The latter, a ventral ramification of the pericardial somatopleure, replaces the yolk sac during early gestation. The external surface of the pericardial trophoderm develops hemispherical projections, termed vascular bulbs. Within each bulb, the vascular plexus of the trophoderm expands to form a blood sinus. Cells of the external surface of the bulbs possess microplicae. Microvilli are absent. During middle to late gestation, the juxtaembryonic follicular epithelium differentiates into two regions. One region consists of shallow, pitlike depressions within which vascular bulbs interdigitate in a “ball and socket” arrangement. Follicular pits are formed by the curvilinear distortion of the apical surfaces of follicle cells. The second region in contact with the dorsal and lateral surfaces of the embryo, is comprised of villous extensions of the hypertrophied follicular epithelium. In both regions, follicle cells appear to constitute a transporting rather than a secretory epithlium. In terms of percentage of weight increase, the follicular placenta of Anableps appears to be the most efficient adaptation for maternal-embryonic nutrient transfer in teleost fishes and closely approaches the efficiency (1.2 × 106%) of oophagy and embryonic cannibalism in lamnoid sharks.
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  • 22
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 155-182 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Regular chewing was studied in the specialized Malagasy insectivore Tenrec ecaudatus with the aid of precisely correlated electromyography of the main adductors, digastrics, and two hyoid muscles and cineradiography for which metallic markers were placed in the mandibles, tongue, and hyoid bone. During the power stroke the body of the mandible moves dorsally and medially. The medially directed component of movement at this time is greatly increased by simultaneous rotation of the mandible about its longitudinal axis. The highly mobile symphysis, spherical dentary condyle, loss of superficial masseter muscle and zygoma, and the simplified zalamnodont molars all appear to be related to the large amount of mandibular rotation that occurs during occlusion. The balancing side lateral pterygoid muscle (inferior head) apparently shifts the working side mandible laterally during the last part of opening and the first part of closing. The working side temporalis and the superficial masseter muscle are both responsible for the shift back to the midline. The temporalis is usually active to the same extent on the working and balancing sides during the power stroke. The level of activity (amplitude) of the temporalis and duration of the power stroke increase with harder foods. Whenever soft foods are chewed, the superficial masseter is only active on the working side; whenever foods of increasing hardness are chewed, its level of activity on the balancing side increases to approach that of the working side. Mandibular rotation is greatly reduced when hard foods are chewed.
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  • 23
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 183-193 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Total dissection of a randomly collected sample of 202 adult and subadult eutherian mammals, combined with site-specific adipocyte volume determination, shows that the number of adipocytes in the body is proportional to (Body Mass)0.74 for predominantly carnivorous species and to (Body Mass)0.78 for mainly herbivorous, nonruminant mammals. Adipocyte expansion or shrinkage, not proliferation or depletion of adipocyte number, is the principal mechanism of adipose tissue enlargement and reduction. Therefore, the adipocytes of large mammals are larger than those of smaller specimens of similar dietary habits and fatness. We suggest that the presence of more numerous, smaller adipocytes in smaller mammals is related to their higher mass-specific metabolic rate. The adipose tissue of mammals with a predominantly carnivorous diet contains 4.6 times as many adipocytes as that of herbivorous nonruminants of similar body mass; but nonruminant herbivores are not necessarily fatter because the adipocytes of carnivorous mammals are proportionately smaller than those of nonruminant herbivores. We suggest that a carbohydrate-based energy metabolism is associated with fewer, relatively larger adipocytes and that when lipids and proteins form the major dietary energy source, adipose tissue consists of a greater number of smaller adipocytes.
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  • 24
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    Journal of Morphology 185 (1985), S. 195-202 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a randomly collected sample of 91 wild and captive birds, in which there is no significant correlation between fatness and body mass, the total number of adipocytes is proportional to (Body Mass)0.68. The adipose tissue of larger birds consists of proportionately fewer adipocytes; therefore, the adipocytes of larger birds are larger, in relation to the fatness of the specimens, than those of the smaller species. The cellularity of the adipose tissue of predominantly carnivorous birds does not differ from that of mainly herbivorous species. The adipocytes in the abdominal cavity and around the thigh are on average 29% larger than those in the superficial and clavicular depots; however, these site-specific differences were variable and were statistically insignificant in many of the specimens. The size of the adipocyte complement is highly variable even among specimens of a single species and similar body mass, suggesting that in birds the number as well as the volume of adipocytes might increase or decrease as the adipose tissue expands or shrinks.
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  • 25
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    Journal of Morphology 185 (1985), S. 145-154 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The composition of myofiber types varies within thigh muscles of chickens. The present study was designed to determine whether or not myofiber types were distributed uniformly across the diameter of the thigh muscles of chickens. Cross sections from middle portions of muscles were used histochemically to examine differences in distribution and composition of myofiber types in the muscles. Myofibers that reacted moderately (M) or strongly (S) for myosin adenosine triphosphatase (ATPase) after preincubation at pH 4.3 were classified as type I. Type I myofibers reacted weakly (W), moderately (M), or strongly (S) for ATPase after preincubation at pH 10.6; these type I myofibers were subclassified into four types (ISW, ISM, ISS, and IMM). Myofibers that reacted negatively for acid-stable ATPase and strongly for alkali-stable ATPase were classified into two types: type IIA, with strong NADH tetrazolium reductase (NADH-TR), and type IIB, with weak NADH-TR activity. The M. pubo-ischio-femoralis pars lateralis had numerous type IIA myofibers and very few type ISM myofibers, whereas the pars medialis had many type IMM myofibers and few type ISS and IIA myofibers. The type I group of myofibers did not exceed about 50% in the other muscles, which had one to three types of type ISW, ISM, and ISS myofibers. The Mm. femorotibiales had more type ISW, and ISM myofibers in the deep regions near the femur than in the superficial regions. The M. iliotibialis cranialis, M. iliofibularis, and M. flexor cruris medialis had more type ISW, ISM, or ISS myofibers in the medial regions than in the lateral regions. A few type ISW myofibers were scattered in the cranial part of M. iliotibialis and in the M. ambiens. The M. flexor cruris lateralis pars pelvica had type IIA and IIB myofibers exclusively. All the muscles had type IIA myofibers. Type IIB myofibers existed in the muscles except the M. puboischio-femoralis. Type IIA and IIB myofibers differed in proportion in different muscles and in their different regions. The type I group of myofibers was generally concentrated more in the deep regions near the femur and in the medial regions than in the superficial and lateral regions of the thigh muscles. The distribution of type IIA myofibers resembled that of type I group. Type IIB myofibers showed a distribution opposite to that of type I group and IIA myofibers. The spatial distribution of myofiber types within individual muscles can account for the various locomotory and postural requirements of the thigh.
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  • 26
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    Journal of Morphology 185 (1985), S. 217-222 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the Mexican axolotl (Ambystoma mexicanum), the pronephros begins to form at the four-somite stage. It is initially continuous with the posterior-lateral region of somite 2 and the lateral margin of somites 3 and 4. By the seven-somite stage, the pronephros has become compacted, and the cells are now morphologically distinct from the somitic cells. At this stage, a mass of loosely connected cells, apparently originating from the lateral mesoderm, is seen below somites 4 and 5. By the eight-somite stage, these presumptive duct cells have migrated dorsally to the duct path and are found below somites 5-7. By the nine-somite stage they have begun to migrate caudally.
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  • 27
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    Journal of Morphology 186 (1985), S. 369-377 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopic observations of the lateral-line organs of larval Ichthyophis kohtaoensis confirmed earlier reports of the occurrence of two different types of lateral-line organs. One type, the ampullary organ, possesses 15-26 egg-shaped sensory cells. Each sensory cell extends a single kinocilium surrounded by a few microvilli into the ampullary lumen. This is in contrast to the ampullary organs of urodele amphibians that contain only microvilli. The second type of organ, the ordinary neuromast, has 15-24 pear-shaped sensory cells arranged in two to three rows. Each sensory cell shows a kinocilium that is asymmetrically placed with respect to both a basal plate and approximately 60 stereovilli. The sensory cells of ampullary organs are always separated by supporting cells; those of neuromasts are occasionally in contact with one another. Numerous (neuromasts) or few (ampullary organs) mantle cells separate the organs from the epidermal cells. Only afferent synapses are found in the ampullary organs whereas vesicle-filled fibers together with afferent nerve terminals are found in neuromasts. Both organs contain similarly sized presynaptic spheres adjacent to the afferent fibers. It is suggested that the neuromasts have a mechanoreceptive function, whereas the ampullary organs have an electroreceptive one.
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  • 28
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 183 (1985) 
    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 183 (1985), S. 15-23 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: At least five nonporous sensilla with inflexible sockets (npsensilla) occur on each antenna of both sexes of adult Rhodnius prolixus. Externally the sensillum appears as a short, rounded peg set into a pit surrounded by a depression. A very electron-dense material occurs in the peg lumen and the inner aspect of the pit. Filamentous extensions of this material radiate into the overlying outlets.Each sensillum is innervated by three neurons with unbranched dendrites. Two dendrites extend to the peg tip and distally are covered by a dendritic sheath. The portion of these dendrites within the sheath contains a large number of microtubules. The third dendrite terminates near the base of the dentritic sheath and partially wraps around the other two dendrites. Three sheath cells are associated with each sensillum.Based on similarities in structure with sensilla of known function it is probable that the np-sensilla of R. prolixus are thermo-/hygrosensilla responding to cold, dryness and wetness. The sensilla have a number of structural similarities with insect rectal sheath cells known to absorb atmospheric water by electroosmosis. Possibly this process leads to volumetric alterations of cuticular elements associated with the dendrites and ultimately to mechanotransduction.
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  • 30
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    Journal of Morphology 183 (1985), 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: The structures and distribution of encapsulated muscle receptors were examined in serial transverse sections of flexor carpi radialis in the adult cat. Four types of receptors (muscle spindles, Golgi tendon organs, paciniform, and Pacinian corpuscles) were identified. Their structures resembled those encountered in other limb muscles. Pacinian corpuscles were rare and occurred only in the external fascial coat of the muscle near its origin. The other three receptor types were distributed in an uneven but consistent pattern throughout the muscle. As noted previously (Gonyea and Ericson, '77), spindles were largely confined to a deep muscle region comprising less than 20% of the muscle volume, located directly between the long tendon of origin and the tendon of insertion. This region contains the largest proportion of type SO muscle fibers (Gonyea and Ericson, '77). Tendon organs and paciniform corpuscles were concentrated along the tendons that lined the spindle-rich muscle region. This region appeared to be composed of extrafusal fibers that were shorter and of more oblique pinnation than those in other regions. The localization of muscle receptors to the “oxidativex” core of the muscle in its direct line of pull may have functional implications for afferent input to the spinal cord which are discussed. In addition, the possibility is raised that there are more paciniform corpuscles in flexor carpi radialis (and possibly other muscles) than previously thought.
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  • 31
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    Journal of Morphology 183 (1985), S. 25-50 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tree sloths, Bradypus and Choloepus, show unusual masticatory specializations, compared to each other and to other mammals. Both have an incomplete zygomatic arch with descending jugal process, a complex superficial masseter, a large temporalis and medial pterygoid musculature, and a lateral pterygoid with two heads. In Choloepus the deep masseter and zygomaticomandibularis are typical when compared to other mammals. However, in Bradypus there is an ascending jugal process from which enlarged and vertically oriented deep masseter and zygomaticomandibularis muscles originate. Although both sloths are folivores, the anterior teeth in Choloepus are caniniform, while those of Bradypus have lost such elongation. In both sloths the glenoid cavity is similarly located; however, in Bradypus the cranioman-dibular joint is raised above the occlusal plane, and the pterygoid flanges are elongated.Prediction of the evolutionary sequence of cranial changes from Choloepus- like (primitive) to Bradypus- like (derived) morphology is based upon the most parsimonious model of masseter-medial pterygoid complex changes for masticatory efficiency improvement. The model proposes that the condylar neck in Bradypus was elongated and that this single change predicated a series of other structural changes.Mandibular movement patterns in both sloths showed anteromedially directed unilateral power strokes as in other mammals. Puncture-crushing, tooth-sharpening, and chewing cycles are distinct in Choloepus, less so in Bradypus. The masticatory rate is slow in sloths compared to other mammals of similar body size, averaging 590 ms per cycle for Choloepus and 510 ms for Bradypus.
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  • 32
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    Journal of Morphology 183 (1985), S. 51-85 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The objectives of this research were to investigate the morphology of the head skeleton and muscles of the female mosquito, Culiseta inornata (Williston). The skeletal parts were examined after maceration in KOH. The attachments of muscles were determined by dissection. Observations were made with the aid of a dissecting microscope at 70× and lower. Each skeletal part and muscle is illustrated and described. Conclusions regarding the skeleton are as follows: (1) the clypeal area is composed of an anteclypeus and postclypeus, (2) the suture between the anteclypeus and postclypeus is rigid and cannot function as a hinge, (3) the dorsal wall of the labrum terminates at its union with the anteclypeus, (4) the dorsal and epipharyngeal walls of the labrum are united apically, (5) the gena and postclypeus are not separated by a suture, and (6) the labellum is composed of three segments and the furca, of some authors, is absent. Twenty-five muscles were identified, and the origin, insertion, and action of each is described. The tormo-epipharyngalis muscle is attached anterior to the cibarium and fulcral plates. Its origin is on the clypeal apodeme and the insertion is on the epipharynx. This result confirms earlier reports and disagrees with some recent authors. The maxillary teeth are not designed to draw the fascicle into the tissues, but the cervical and leg muscles accomplish the probing process during feeding on a host. An undescribed muscle of the mandible is reported.
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  • 33
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    Journal of Morphology 183 (1985), S. 145-153 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The differentiation of fiber type characteristics in the anterior (ALD) and posterior (PLD) latissimus dorsi muscles is examined by the freezefracture technique in 1-, 7- and 30-day-old chicks. Several characteristics of plasma membrane (caveolae, rectilinear arrays, intramembranous particles) and sarcoplasmic reticulum which show fiber type differences in the adult ALD and PLD muscles are compared in the developmental stages. The caveolar density in the ALD fibers is about 20/μm2 at 1 day increasing to about 37/μm2 at 30 days, whereas in the PLD fibers it remains at about 20/μm2 during this period. The distribution of the caveolae in the two muscles is different from the begining; in the ALD fibers the caveolae are distributed throughout the plasma membrane and in PLD fibers they are patterned into clusters overlying the I band regions. The density of intramembranous particles of 1-day ALD and PLD plasma membranes appears similar, but by 7 days the particle counts in the sarcolemma of the ALD muscle are about twice as numerous as those in the PLD muscle. The rectilinear arrays are virtually absent in the ALD muscle, whereas in the PLD muscle their density is about 10/μm2 at 1 day and about 20/μm2 at 7 days. Already at 1 day posthatching the SR in ALD and PLD fibers has the adult configuration, i.e., an open irregular network in ALD fibers and periodically arranged tubules with triadic expansions in the PLD fibers. It is concluded that the membrane structure of ALD and PLD muscles is already different at hatching, and at 1 week the differences are identical to those of slow and fast fibers of the adult stage. The membrane changes, therefore, do not support the view that the ALD muscle undergoes a transitional, fast-type stage in posthatching chicks.
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  • 34
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    Journal of Morphology 183 (1985), S. 165-176 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytodifferentiation and hard tissue formation were studied in Anolis to collect information regarding the phylogenetic history of enamel and the functional significance of the events seen in the mammalian tooth during differentiation. The differentiation of the ameloblasts of Anolis, like that of mammals, shows two phases: In the early phase, the cells are short and rich in free ribosomes, in the late phase the cells elongate, develop an extensive rough endoplasmic reticulum, and the Golgi apparatus moves into that part of the cell next to the basal lamina (the cell apex). The early epithelial-mesenchymal interface resembles that of mammals, suggesting that early mechanisms of induction and epithelial-mesenchymal interaction are similar in Anolis and in mammals.Preameloblast processes and preameloblast-preodontoblast contacts in Anolis are rudimentary compared to those of mammals. While in mammals the preameloblast processes shape the future DEJ (dentin-enamel junction), their involvement in establishing the shape of the DEJ of Anolis is questionable. We suggest that the great development of preameloblast-preodontoblast contacts in mammals may simply increase the efficiency of inductive interactions between these cell types.
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  • 35
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    Journal of Morphology 183 (1985), S. 177-183 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spermatozoa of Rhinolophus capensis are stored in the cauda epididymidis for about 10 months, 4 months prior to copulation and 6 months after copulation. Electron microscopy has shown the occurrence of sperm defects (mitochondrial proliferation, bending and coiling of the tail, and Dag defect) throughout the period of sperm storage. However, these defects are more common during the postcopulation period, when excess spermatozoa are being removed, suggesting that they may be associated with sperm degradation.
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  • 36
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    Journal of Morphology 186 (1985) 
    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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  • 37
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning electron microscopy of six stages of Lytechinus variegatus embryos from hatching through gastrulation reveals changes in the shapes of the ectodermal cells and morphological changes in the extracellular material (ECM) in relation to the locations and migratory activities of mesenchyme cells. The classical optical patterns in the blastular wall (Okazaki patterns) are due to differential orientations of the cells, which bend and extend sheet-like lamellipodia over adjoining cells toward the eventual location of the primary mesenchymal ring. The blastocoelic surfaces of the blastomeres become covered with a thin basal lamina (BL) composed of fibers and nonfibrous material. During primary mesenchyme cell (PMC) ingression, a web-like ECM is located in the blastocoel overlying the amassed PMCs. This ECM becomes sparse in migratory mesenchyme blastulae, and is confined to the animal hemisphere. Localized regions of intertwining basal cell processes in the blastular wall are also present during PMC migration. While a distinct BL is present during early and midgastrulation, blastocoelic ECM is absent. Late gastrulae, on the other hand, have an abundance of blastocoelic ECM concentrated near secondary mesenchyme cell protrusive activity. ECM appearing at both the early mesenchyme and late gastrula stages are probably remnants of degraded BL and intercellular matrix preserved by fixation for SEM. Thus, early mesenchyme ECM is formed of BL material whose degradation is necessary for entry of PMCs into the blastocoel. Late gastrula ECM is apparently a degradation product of BL and intercellular material whose destruction is required for fusion of the gut with oral ectoderm in formation of the mouth.
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  • 38
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The teeth of the adult plethodontid salamander, Plethodon cinereus, were examined by light and electron microscopy with emphasis on the ringlike zone of uncalcified dentin that divides the calcified portion of each tooth into a proximal pedestal and a distal apex. The uncalcified region displays radial asymmetry, forming an integral part of the posterior wall of the tooth but bulging into the pulp cavity anteriorly, thus forming a hingelike structure. All portions of the dentin, including the uncalcified region, are composed predominantly of collagenous fibers but lack elastin. In scanning electron micrographs of teeth from which the oral mucosa has been removed, the location of the anterior uncalcified hinge is marked externally by a notch-like articulation of the apex and pedestal. Sites of transition between calcified and uncalcified areas of the dentin show no special modifications in transmission electron micrographs, but collagenous fibers in calcified portions are associated with more electron-dense amorphous material than are those in the uncalcified region. Odontoblasts associated with the uncalcified region possess ultrastructural features closely resembling those of odontoblasts found in calcified areas. The uncalcified region seems to afford the teeth a certain degree of flexibility, and the asymmetry of the region appears to allow the teeth to flex only in a posterior direction, thus facilitating the entry of living prey but hindering its escape. The uncalcified region also seems to permit the apex of a tooth to break away from its pedestal without damage to underlying bone.
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  • 39
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    Journal of Morphology 186 (1985), S. 31-44 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paired salivary glands of unfed adult Haemaphysalis (Rhipistoma) leachi contain one type of agranular and three types of granular alveoli connected to a salivary duct system. Type I agranular alveoli consist of one large, central cell surrounded by peripheral cells with numerous basal membrane infoldings indicative of epithelia involved in fluid transport. Glycogen particles, lipid-like droplets, and the parallel pattern of infolded membranes disappeared from the peripheral cells during feeding. Types II, III, and IV granular alveoli contain some agranular interstitial epithelial cells, cap cells, and fundus cells, but are predominantly composed of structurally different granular cell types a, b, c, d, e, and f. Agranular cells develop during the early stages of feeding. Granular a, c, e, and f cells release their granules directly after attachment to the host and possibly are involved in cement secretion required for firm attachment to it. The b cell granules are replaced by b1 filamentous granules during feeding. Golgi bodies and rough endoplasmic reticulum (RER) participate in the formation of most types of granules. The d cells contain lamella-like structures and condensing vacuoles, probably responsible for lysosome formation. The main salivary duct and all types of alveoli are innervated by neurosecretory axons.
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  • 40
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    Journal of Morphology 183 (1985), S. 129-129 
    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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  • 41
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Muscle architecture, moment arms, and locomotor movements in the distal limb segments of the procyonids Nasua (coati) and Procyon (raccoon) are analyzed with reference to patterns of muscle fiber length. This study addresses the hypothesis that relative fiber lengths among muscles in a muscle group can be predicted on the basis of correlates of muscle tension. The results include the following: (1) consistent patterns of fiber length of muscles in a muscle group exist within and between the two genera. (2) Differences in fiber length between muscles can be accounted for by two principal correlates of muscle excursion - length of a muscle's moment arm about a joint and jointangle excursion. (3) Muscle fiber pinnation permits increased tendon excursion, but this effect is relatively small in comparison to the effects of moment-arm length and joint-angle excursion. (4) Corollary action between two or more joints (or lack thereof) is an important factor in determination of fiber lengths.
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  • 42
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    Journal of Morphology 183 (1985) 
    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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  • 43
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Germanium (Ge), in the form of germanic acid, at a Ge/Si molar ratio of 1.0 inhibits gemmule development and silica deposition in the marine demosponge Suberites domuncula. Lower Ge/Si ratios inhibit the growth in length of the silica spicules (tylostyles) producing short structures, but with relatively normal morphology and close to normal width; spherical protuberances occasionally occur on these spicules. A few of the short spicules possess completely round rather than pointed tips. Many of the latter develop when Ge is added (pulsed) to growing animals, thus inducing a change in spicule type. These results indicate that the growth in length of the axial filament is more sensitive to Ge inhibition than is silica deposition and that pointed spicule tips normally develop because the growth of the axial filament at the spicule tip is more rapid than silica deposition. Newly formed spicules initiate silica deposition at the spicule head but the absence of Ge-induced bulbs as in freshwater spicules (oxeas) leaves open the question of whether there is a silicification center(s) present in Suberites tylostyles. The morphogenesis of freshwater oxeas and of marine tyolstyles appears fundamentally different-bidirectional growth in the former and unidirectional growth in the latter. X-ray analysis demonstrate relatively uniform Ge incorporation into the silica spicules with considerable variation from spicule to spicule in the incorporated level. Increased silicic acid concentration induces the formation of siliceous spheres, suggesting that the axial filament becomes prematurely encased in silica.
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  • 44
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    Journal of Morphology 183 (1985), S. 137-144 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The present study investigates the morphological aspects of nonself recognition between three incrusting sponge species living in contact.Two types of association have been observed: nonmerging fronts and epizoism. In two of the three combinations studied, Hymeniacidon sanguinea/Halichondria panicea and Halichondria panicea/Ophlitaspongia seriata, nonself contacts consisted of either epizoism or of nonmerging fronts. In contrast, only nonmerging fronts were observed between Hymeniacidon sanguinea and Ophlitaspongia seriata.In the two types of associations, the main phenomenon consists of the isolation of the foreign sponges by a spongin barrier secreted by the partners in the zone of contact. The microscpic structure and the thickness of the barrier vary according to the type of association and the species paired, but they are clearly defined for a given combination.The conditions required for the establishment of epizoism and the existence of a natural xenogeneic tolerance between sponges are discussed.
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  • 45
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Immunocytochemical investigation of the eyestalks of the larval and postlarval stages of the crayfish Astacus letodactylus, using an anti-Astacus-CHH serum, shows that immunopositive staining starts in the immediate posthatching larval stage, in neurosecretory cells of the medulla terminalis ganglionic X-organ (MTGX), in an MTGX-sinus gland tract, and in part of the axon terminals of the sinus gland. The number of these immunopositive cells increases during postlarval development. Neurosecretory granules belonging to distinct axon terminals of the neurohemal region show immunostaining. The mean diameter of the stained granules increases during postlarval development. The hemolymph glucose concentration in adult crayfish increases after injection of larval eyestalks.
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  • 46
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the development of the horseshoe crab, Limulus polyphemus, the fertilized egg undergoes a complicated cleavage (Stages 1-3) resulting in blastoderm formation (Stage 4). Stage 1 involves intralecithal cleavage and consists of nine discrete surface modifications (events) which have been briefly described with light microscopy by Brown and Barnum ('83). Since in Stage 1 the cortical reaction (events 1-4) has already been examined with ultrastructural methods, the objectives of the present study were to examine with scanning electron microscopy: (1) the first two of three intermittent granulations (events 5 and 7), and (2) the associated events characterized by smooth surfaces (events 4, 6, and 8). The first granulation occurs 2 1/2 to 3 hours after fertilization (22°C) and lasts approximately 1 1/2 hours. The second granulation appears approximately 5 hours after fertilization and lasts about 3 hours.The dynamic changes that occur during the two granulations involve the transformation of a smooth appearing embryonic surface, liberally coated with microvilli, into a granule-dominated surface on which microvilli are greatly reduced in number. Also of considerable interest are the numerous projections which begin to appear on the surface near the end of the second granulation (event 7) and dominate the surface of the following smooth step stage (event 8). Hypotheses on the significance of these dynamic changes and surface modifications involve relationships to the cell cycle, possible mechanisms for membrane storage, and secretory function.
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  • 47
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    Journal of Morphology 183 (1985), S. 219-224 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural study of previtellogenic oocytes found in cystlike clusters scattered throughout the length of the bilobed ovary of the hermit crab Coenobita clypeatus shows a high nuclear:cytoplasm ratio. Large, round nuclei containing synaptinemal complexes serve as good temporal markers for identification of previtellogenic oocytes. The cytoplasm contains many smooth-membraned vesicles filled with granules and probably of nuclear origin. In addition to its complement of Golgi complexes, endoplasmic reticulum, mitochondria, and free ribosomes, the cytoplasm also contains stacks of annulate lamellae, a feature not previously described for decapod oocytes. Typically, the previtellogenic oocyte with its accumulation of ribosomes has the appearance of a nonsynthetic cell preparing to go through a metabolic transition.
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  • 48
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    Journal of Morphology 183 (1985), S. 199-217 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The major cranial vibrissae in the golden hamster can be moved in complex ways that suggest they are served by a finely controlled motor system. Movements are hypothesized to be the products of (1) differential blood flow and pressure regulation in the sinus surrounding each vibrissal follicle, (2) contractions of the striated facial muscles, and (3) elastic rebound in the connective tissues. The vasculature contributes hydrostatic forces that (a) erect the vibrissae slightly and distort their connective tissue bedding, (b) rigidify the vibrissal capsules, thus forming firm bases of attachment for certain facial muscles, and (c) theoretically provide a pressure plate around the follicle, important in lowering the firing thresholds of receptor endings. The facial muscles supply the major forces in erection and protraction of the vibrissae by acting on both the capsules and the connective tissue bedding. The connective tissues are organized into capsular and extracapsular systems that serve to stabilize the vibrissae and return them to initial rest positions.The slight movements of the genal vibrissa are the effects of vascular and connective tissue dynamics, the musculature being uninvolved. Wide angle movements of the supraorbital vibrissae are products of the vasculature and connective tissues, plus contractions of the Mm. orbicularis oculi and frontalis. Mystacial vibrissal movement is quite complex. The vasculature supplies a small degree of capsular erection and mystacial pad distortion, but primarily rigidifies the capsules. The bulk of erection and protraction is produced by the M. nasolabialis profundus (NLP) and the vibrissal capsular muscles (VCM). The NLP distorts the mystacial pad; the VCM tilt the capsules relative to the pad. Retraction is mainly accomplished by elastic rebound in the pad, this being aided in its extreme degrees by the Mm. nasolabialis and maxillolabialis. The Mm. nasolabialis superficialis and buccinator pars orbicularis oris help to spread the vibrissae into a dorsoventral fan and stabilize the mystacial pad during whisking.
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  • 49
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    Journal of Morphology 183 (1985), S. 311-326 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: External features of the egg, developing embryo, and first instar nymph of Kamimuria tibialis are described. The embryonic development from the germ disc to the full-grown embryo is divided into 12 stages. The saclike embryonic rudiment is formed by the bending and folding of the germ disc. The embryo first elongates at the egg surface and then sinks into the yolk due to caudal flexure. In the head, four paired protocerebral lobes differentiate and the fourth lobes are thought to be the rudiments of preantennal ganglia. The columnar serosal cells appear at the posterior pole of the egg and they disappear before katatrepsis. The coniform chloride cells occur at the hind margins of the first nine abdominal segments in the full-grown embryo and first instar nymph. Amnion formation in K. tibialis is very similar to that of Allonarcys proteus and the Isoptera. It is proposed that the immersed type of growth pattern of embryos is divided into two subtypes in hemimetabolous insects; one is in the Palaeoptera and Paraneoptera, and the other is in the Plecoptera, Orthoptera, Notoptera, Isoptera, Embioptera, and the blattarian, Periplaneta americana.
    Additional Material: 35 Ill.
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  • 50
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study was designed to investigate and determine for how long, after either hypophysectomy or the third (last) growth hormone injection (to previously hypophysectomized newts), the circulating and now declining titers of endogenous or exogenous hormone remained at a sufficient concentration to permit a morphologically normal forelimb regeneration response in the adult newt Notophthalmus viridescens.To examine the declining levels of endogenous hormone (hormone withdrawal series [HW]), left forelimbs were amputated at specific times following hypophysectomy. Right forelimbs were amputated 5 days prior to hypophysectomy. The declining levels of exogenous hormone hormone replacement series [HR] were examined in newts whose left forelimbs were amputated at specific times following the last of three consecutive alternate-day growth hormone injections that were initiated 5 days post hypophysectomy. Right forelimbs were amputated immediately following the first hormone injection. All experimental animals were sacrificed when their right forelimbs regenerated to an advanced digitiform regenerate. In both series right forelimbs regenerated normally.In the HW series normal regeneration resulted only when forelimbs were amputated within 48 hours post hypophysectomy, whereas in the HR series normal regeneration occurred in only those newts whose forelimbs were amputated within 12 hours of the last hormone injection. The regeneration response of left forelimbs in both series gradually declined with the time interval between either hypophysectomy or hormone injection and forelimb amputation. As the hormone titer declined, fewer limbs initiated a normal response; they became progressively more hypomorphic and eventually failed to undergo typical regeneration.
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  • 51
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    Journal of Morphology 184 (1985), S. 263-276 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the ovarian follicle, the micropylar cell (MPC) is distinguished from neighboring granulosa cells by its larger cell size and its thick cytoplasmic process. The micropylar cell body fits into a shallow depression (micropylar vestibule) on the outer surface of the egg envelope; its process extends through the micropylar canal, which extends from the bottom of the vestibule through the full thickness of the zona pellucida interna. At its distal end, the cell process expands into a bulb which fits into an indentation of the ooplasmic surface immediately beneath the inner opening of the micropylar canal. Intermediate and desmosomelike junctions establish an intimate association between MPC process and oocyte. Various kinds of organelles and inclusions in the MPC show a characteristic pattern of cytoplasmic distribution; rough endoplasmic reticulum with markedly dilated cisternae is found exclusively in the main cell body, while microtubules and thin filaments are observed in the cytoplasmic process.Immediately before or during the breakdown of the germinal vesicle in the intrafollicular oocyte, the cytoplasmic process of the MPC gradually decreases in length and begins to withdraw from the micropylar canal. At the same time, the ooplasmic surface protrudes outward to form a papilla in the canal. The intimate MPC-oocyte association disappears during formation of the ooplasmic papilla. Hydration of the oocyte apparently occurs at the final stage of maturation and probably participates in papilla formation. Although the MPC undergoes degenerative changes as ovulation draws near, it remains attached to the inner surface of the granulosa cell layer even after its association with the oocyte has completely disappeared.We speculate that the micropyle develops during fish oogenesis through the combined activity of the MPC and neighboring granulosa cells. It appears that the cell body of the micropylar cell and nearby granulosa cells exert mechanical pressure on the external surface of the growing oocyte and thus participate in formation of the micropylar vestibule. The cytoplasmic process of the MPC evidently forms a passive barrier to deposition of material for the egg envelope in the animal pole, thereby resulting in formation of the micropylar canal.
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  • 52
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    Journal of Morphology 184 (1985), S. 277-292 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and non-gravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well-vascularized bed of connective tissue. Cells of the IOE are apically convex. Well-developed granular and agranular endoplasmic reticula and numerous large membrane-bound vesicles with electron-dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal-embryonic nutrient transfer processes.
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  • 53
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    Journal of Morphology 184 (1985), S. 311-321 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), has one continuous network of connective tissue in which the tubules are embedded and suspended and which forms the limiting layer of the organ. Light- and electron-microscopical observations show that the outer connective-tissue layer investing the entire digestive gland is a typical, fibrous connective tissue, containing hemal sinuses and a variety of cell types embedded in a collagenous matrix. This outer layer is continuous with the connective tissue among the tubules, which lacks a substantial fibrous matrix and lies peripheral to the digestive epithelium of each tubule. It consists of a complex, two-layered, epithelial basement membrane, an area containing cells, a tunica propria, and hemal sinuses. Several types of cells are present between the basement membrane and the tunica propria: contractile cells form a network of circular and longitudinal processes around each tubule, and several types of granulocytes are found in areas where tubules abut.The previously applied terms “myoepithelium” and “myoendothelium” are inappropriate to describe the tissue among the tubules. Instead, the extraepithelial elements are interpreted as forming an extensive connective tissue supporting the functional units of the digestive gland.
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  • 54
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    Journal of Morphology 184 (1985), S. 293-309 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of the viviparous goodeid fish Ameca spendens develop within the ovarian lumen, where they establish a placental association with the maternal organism and undergo a 15,000% increase in embryonic dry weight. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the internal ovarian epithelium. Examination with light microscopy and with transmission and scanning electron microscopy reveals that trophotaeniae of A. splendens are extraembryonic membranes consisting of five ribbon-like processes originating from a tube-like mass of tissue that extends outward from the perianal region of developing embryos. There are two sets of lateral processes and a longer single median process. Trophotaeniae possess an outer epithelium that surrounds a highly vascularized core of loose connective tissue. Epithelial cells possess apical microvilli and a pronounced endocytotic apparatus. Cells of the trophotaenial epithelium are either tightly apposed along their lateral margins or separated by enlarged intercellular spaces. Regions of the trophotaenial epithelium possessing enlarged intercellular spaces are distributed in patches. The trophotaenial epithelium is continuous with the embryonic hindgut epithelium and is considered to be derived from it. Comparison of trophotaenial morphology in A. splendens with that reported in Xenotoca eiseni reveals differences in histological organization. The former possess unsheathed trophotaeniae, whereas the latter are sheathed. We postulate that the apposition of trophotaenial epithelium to the internal ovarian epithelium constitutes a placental association equivalent to a noninvasive, epithelioform of an inverted yolk sac placenta. Structural relationships of embryonic and maternal tissues of the trophotaenial placenta are discussed in relation to maternal-embryonic nutrient transfer processes.
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  • 55
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    Journal of Morphology 184 (1985), S. 323-341 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural and light microscopic observations on the organization of thick and thin regions of hydra's tentacles, made on serial sections and on whole fixed, plastic-embedded tentacles, reveal the existence of two levels of anatomical order in the tentacle ectoderm: (1) The battery-cell complex (BCC), composed of a single epitheliomuscular cell (EMC) and its content of enclosed nematocytes and neurons; and (2) the battery cell complex ring (BCC ring), an arrangement of 4 or more BCCs into larger units organized as rings around the circumference of the tentacle. All EMCs of the distal tentacle appear to contain batteries of nematocytes, and are, therefore, called “battery cells.” Apart from battery cell complexes and migrating nematocytes, there are no other cell types in the tentacle ectoderm. Battery cells are composed of three distinct regions: the cell body, peripheral attenuated extensions and myonemes. Thick tentacle bands are composed of cell bodies, whereas thin bands are made up of attenuated extensions. Myonemes contribute to both thick and thin regions. It was confirmed that each battery cell has several myonemes, which appear to interdigitate with myonemes of other more proximal and distal battery cells, but not with battery cells of the same BCC ring. Nematocytes have several basal processes. Some processes insert between myonemes and contact the mesoglea; other processes insert into cuplike extensions of myonemes, and are connected to myonemal cups by desmosomal junctions. These observations are discussed in relation to mechanical and electrical aspects of tentacular contraction and bending.
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  • 56
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    Journal of Morphology 184 (1985), S. 343-350 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To characterize and classify erythrocytes of ranid tadpoles, alcohol-fixed blood smears were studied with dark field illumination. All preclimax stage (limb bud-foot) Rana castesbeiana tadpoles from ponds in Massachusetts had red blood cells that were polymorphic. The majority of cells (88%) showed a bright, granular luminescence varying from white to blue-grey, whereas, cytoplasm of the other cells was smooth, black, and nonluminescent. On the other hand, tadpoles in similar stages from other species (Rana clamitans, Mass. and Rana pipens, Vermont) and from R. catesbeiana tadpoles from other locations (Wisconsin and North Carolina) had no observable cytoplasmic luminescence in any of their red blood cells. Moreover, as Mass. R. catesbeiana underwent metamorphic climax their luminescent cells disappeared and were replaced by small, round, dark, nonluminescent cells, precursors of the oval, nonluminescent erythrocytes characteristic of adult frogs. Cells with black nonluminescent cytoplasm generally contained nuclei which were luminescent. In conclusion, two main types of red blood cells-those with and those without cytoplasmic luminescence-are distinguishable with dark field microscopy. Luminescence of the cells varies with species, geographic location, and developmental stage of the tadpoles.
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  • 57
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    Journal of Morphology 184 (1985), S. 351-360 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Serial sections of 13 embryos and fetuses of the harbor porpoise from 10 mm crown-rump length up to 167 mm total length were studied. Unlike the adult animals, ontogenetic stages of 18-27 mm crown-rump length still show a typical mammalian olfactory bulb. The olfactory bulb primordium is penetrated by olfactory nerve fibers, the latter passing through the cribriform plate. However, the olfactory bulb anlage is gradually reduced in later stages, its placodal component being largely uncoupled from the telencephalon. As a ganglionlike structure, the remains of the placodal component stay in contact with the nasal septum and mucosa via thin bundles of nerve fibers. The ganglion and plexus can be traced within the meninges until the adult stage of the porpoise. There is strong evidence that they represent the material of the terminalis system, which cannot be distinguished from the olfactory system in earlier stages. A vomeronasal organ could not be detected in the embryonal and fetal material investigated.
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  • 58
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    Journal of Morphology 184 (1985), S. 361-373 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The kidneys of Phoca hispida are comprised of many closely adherent renculi, each of which is a small kidney, functionally independent of its neighbours except with respect to venous drainage. Venous blood from the rencular parenchyma drains to the periphery through interlobular veins. These interlobular veins empty into a perirencular plexus comprised of subcapsular veins on the free surface of the renculus, interrencular veins on adjoined surfaces, and marginal subcapsular veins lying in the furrows between adjoined renculi. A pericapsular plexus of large veins overlies the marginal subcapsular veins and has frequent connections with them. Blood drains from the pericapsular plexus into large superficial collecting veins that converge over the surface of the kidney toward the divided hilum and connect directly to the paired trunks of the posterior vena cava. There are also connections to other major venous systems of the region.There is no arcuate venous system, no major vein at the rencular hilum, and no vein of consequence emerging from the renal hilum. Venous outflow is virtually entirely directed to the peripheral plexuses. The venous pattern differs from that of most mammals in which blood drains from the renal parenchyma to arcuate veins and leaves the kidney through a renal vein, or veins, emerging from the hilum.The walls of veins in the kidney are remarkably thin in comparison to their size. Subcapsular veins up to 0.5 mm wide have walls on the parenchymal side that in places consist only of a thin, fenestrated endothelium and a basal lamina.
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  • 59
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985) 
    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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  • 60
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    Journal of Morphology 184 (1985), S. 375-387 
    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 the entire complex of the superficial calf muscles, as well as individually for the Mm. soleus, plantaris, and gastrocnemius, caput mediale and laterale, of eight male Wistar rats. The M. soleus composes approximately 5% of the weight and cross-sectional area of the entire group of superficial calf muscles and is the only muscle of the group containing mainly slow-twitch fibers. The other superficial muscles of the calf are primarily fast-twitch muscles.The mono-articular M. soleus, the bi-articular M. gastrocnemius, caput mediale and laterale, and the poly-articular M. plantaris differ with respect to the number of joints crossed. However, contrary to the findings for cat hind limbs (Goslow et al. [1977] J. Morphol. 153:23-38), the muscles of the complex of superficial calf muscles of the rat did not differ with respect to (a) their fiber optimum length, (b) their maximum length range of active force generation, (c) the relative increase of passive force owing to lengthening of the muscle, (d) the angle of the ankle at which they produce maximal active force (the knee angle was fixed at 90°).
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  • 61
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    Journal of Morphology 185 (1985), S. 51-58 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Calcium is demonstrated by energy and wavelength dispersive X-ray microanalysis to be the major component of the granules that fill the fuselli of the organ of Bellonci in Gammarus setosus. The presence of calcium was confirmed by chelation with EDTA and by other cytochemical techniques. X-ray microanalysis indicated the simultaneous presence of iron in the region of the fuselli occupied by the calcium granules, but this could not be confirmed by cytochemical means in resin-embedded tissue by light or transmission electron microscopy.
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  • 62
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The present study reports on the spermiogenesis and spermatozoa of seven labidognath spiders: Filistata insidiatrix (Filistatidae), Segestria senoculata (Segestriidae), Dysdera sp., Harpactea hombergi (Dysderidae), Oonops domesticus (Oonopidae), Scytodes thoracica (Scytodidae), and Pholcus phalangioides (Pholcidae). Filistata insidiatrix is the first cribellate spider whose spermatology is described electron microscopically. A common characteristic of the spermatozoa of the cribellate spider and the remaining species, often referred to as haplogyne spiders, is the coiling process that occurs at the end of spermiogenesis. As a result of coiling, an elongated spermatid is converted into a lens-shaped structure with the flagellum bearing a 9 × 2 + 3 axoneme becoming incorporated into the cell body. Remarkable differences regarding the main components (shape of nucleus, acrosomal vacuole, implantation fossa, and centriolar complex) probably reflect systematic relationships.The formation of sperm capsules and sperm balls is described for the first time in detail. Sperm capsules occur in Filistata, in which numbers of individual spermatozoa are grouped together by a common secretory envelope established in the distal vas deferens. In contrast, in the sperm balls, two (Harpactea) or four (Segestria, Dysdera, Seytodes) spermatids fuse completely at the end of spermiogenesis. These sperm balls, considered unique in the animal kingdom, are also provided with an envelope. A further peculiarity not reported previously is the occurrence of a large vesicular area in the sperm balls of Dysdera and Harpactea; this area is also found in Oonops, which, however, possesses individual spermatozoa. Components of the spermatozoa such as the acrosomal vacuole, part of the nucleus, and the axoneme protrude into this area and are thus secondarily covered with a membrane.A detailed study of the individual spermatozoa of Pholcus phalangioides completes earlier investigations and stresses the exceptional position of the genus in comparison to that of other spiders.
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  • 63
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    Journal of Morphology 185 (1985), S. 37-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Developing ovarian follicles of Bacillus rossius have been examined ultrastructurally in an attempt to understand how inception of vitel-logenesis is controlled. Early vitellogenic follicles are characterized by a thick cuboidal epithelium that is highly interlocked with the oocyte plasma membrane. Gap junctional contacts are present both at the follicle cell/oocyte interface and in between adjacent follicle cells. In addition, microvilli of follicle cells protrude deeply into the cortical ooplasm of these early vitellogenic oocytes. With the onset of vitellogenesis, wide intercellular spaces appear in the follicle cell epithelium and at the follicle cell/oocyte interface. Gap junctions become progressively reduced both on the follicle cell surface and on the oocyte plasma membrane. Microvilli from the two cell types no longer interlock.From a theoretical standpoint each of the two structural differentiations present at the follicle cell/oocyte interface - gap junctions and follicle cell microvilli - could potentially trigger inception of vitellogenesis. Gap junctions might permit the passage of a regulatory molecule, transferring from follicle cells to oocyte, which would control the assembly of coated pits on the oocyte plasma membrane. Alternatively cell interaction via microvilli might induce the appearance of coated pits, thus creating a membrane focus for vitellogenin receptors. Both possibilities are discussed in relation to current literature.
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  • 64
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Comatulids are able to perform quick and complex movements of the arms which are used to swim, creep, walk, and also form a rigid, feeding-filtration fan. To perform such versatile movements, the arms of these animals are equipped with a classical endoskeletal system, with joints, muscles, ligaments, and a hydroskeleton of three different coelomic channels. Light microscopic study of the detailed anatomical organization of the arm clarifies both the complex relations between the parts involved in the movements and their functional responsibilities. In particular, (1) the ventral muscle bundles show a heterogeneous structure that consists of different and variously arranged populations of fibers, which allows the different flexing movements of the arms (i.e., flexion and maintaining the flexed state); (2) the ligaments (both dorsal and interarticular) consist only of collagen fibrils and, therefore, have a passive function in binding the skeletal pieces together: their possible active engagement in the extending movements of the arms is thus excluded; (3) owing to the absence of other suitable antagonists to the flexor muscles, the only efficient antagonist system seems to be the coelomic cavities, which are well separated from each other and are also provided with muscular valves. They thus function as typical hydraulic systems, which allows the arm to perform both simple extensions and very complex combined movements and to maintain some rigid straight or twisted positions.
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  • 65
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    Journal of Morphology 186 (1985), S. 255-264 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five types of hemocytes, prohemocytes, typical plasmatocytes, coagulocytes, spherule cells, and oenocytoides, have been defined in the last larval instar of Heliothis armigera on the basis of ultrastructural microscopy, smears, and optical phase-contrast microscopy. Modifications in typical plasmatocytes and coagulocytes have been evidenced in the course of development in this instar, which suggests that these hemocytes are involved in physiological processes of development. Only coagulocytes exhibit endocytotic capacities. Phenoloxidase activity was observed in oenocytoides.
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  • 66
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    Journal of Morphology 186 (1985), S. 265-269 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study using eight rapidly growing young green iguanas (Iguana iguana; initial mean weight 68.0 ± 3.8 gm) examined the changes in the wave replacement of teeth, the increased size of the teeth, and the posterior migration of tooth positions over a period of 16 weeks. The teeth increase in width as the lizards grow. The tooth positions shifted posteriorly, providing adequate space for the larger replacement teeth. These observations suggest that the wave replacement of teeth allows for growth of the dentition in length and height adequate to maintain tooth size in proportion to the overall size of the individual.
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  • 67
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    Journal of Morphology 186 (1985), S. 195-207 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The silk production systems of several specimens representing at least three species of the mygalomorph genus Euagrus were examined by dissection and by a variety of absorption and fluorescent histochemical techniques. The intrageneric variation is primarily restricted to gland number, with larger numbers of glands in the larger-bodied species. The silk glands are arranged in four groups each serving one of four spinnerets. Spigot morphology is uniform, consisting of a long, slender shaft of slightly variable length emerging from an enlarged sac-shaped base. Only one gland type is identified histochemically, although a considerable range in size and shape is observed. Each gland has three secretory zones, a distal one that produces a largely hydrophobic protein core and medial and proximal zones that produce distinct charged protein coatings. Amino acid analysis of the silk indicates a composition very similar to the frame threads and draglines of araneomorph spiders. The high percentage of short side-chain amino acids implies a polymer structure able to support the suspended entrapment web found in Euagrus and its relatives (but which is rare in most other nonaraneomorph families). Dry silk examined under high magnification appears smooth and homogenous. The fact that in the web larger threads appear to fibrillate suggests that Euagrus silk is polyfilamentous.
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  • 68
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    Journal of Morphology 186 (1985), S. 271-278 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Calcitonin-containing cells (C cells) were identified in male Wistar white rats using an immunoperoxidase technique. They occupied a central position within the thyroid; very few were found peripherally, inferiorly, and superiorly; and none were present in the isthmus. The number of calcitonin-containing cells present per gram of body weight increased with age up to 70 days and had declined by 100 days. Determining the true total C-cell count through the entire thyroid is a very laborious procedure. However, a simple estimate of this total count can be made; the total number of C cells in every tenth section (6 μm) of thyroid was found to be highly correlated with the weight of the animal expressed as an allometric function. A better estimate can be derived from counts of just three sections: the tenth, twentieth, and thirtieth after the section of greatest cross sectional area.
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  • 69
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    Journal of Morphology 186 (1985), S. 343-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this astrophorid sponge, both intercellular fibrils and spongin microfibrils are elaborated with the former forming exceptionally dense arrangements throughout much of the matrix. Fibrils are very dense below the surface where they surround the small silica asters and throughout the cortex in the form of bundles that can form pseudo-plywood arangements. In the endosome, fibril bundles are isolated and fewer in number. The surfaces of the large silica spicules are uniquely encased by intercellular fibrils or compacted intercellular fibrils that form a type of “fibrillar spongin” or spongin microfibrils intermixed with fibrils. Well developed microfibrillar spongin, intermixed with some fibrils, encases larger spicules below the sponge surface within the tissue and extends above the tissue surrounding spicules that emerge from the sponge thus placing this fibrillar matrix in direct contact with the sea water. The results of other studies suggest that the fibrils and microfibrils of this species are collagenous. The elaboration of these special matrices indicates that the differentiation of spongocytes (which secrete microfibrils) is weak and that the activity of lophocytes (which secrete fibril bundles) is highly labile. The variability of the fibrillar arrangements in this species supports the view that astrophorid sponges are possibly important for understanding the phylogeny of the organic skeletal matrix of sponges.
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  • 70
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    Journal of Morphology 186 (1985), S. 361-368 
    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 dorsal proctodeal gland of the mature male turkey closely resembles that of the proctodeal gland of the mature female Japanese quail. This exocrine gland is a collection of compound, coiled, tubular units. Diffuse lymphoid tissue and germinal centers are distributed throughout the lamina propria and are closely associated with the surface and glandular epithelia. The morphology and histochemistry of the proctodeal gland mucosa suggest that it may secrete muco-substance(s) and may have immunogenic capabilities.
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  • 71
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It is known that a number of species in the annelid family Lumbricidae harbor symbiotic microorganisms in the lumen of their nephridia. The purpose of the present paper is the study of the relationship between microbes and epithelial cells lining the metanephridium of two species of Oligochaeta, which show two different patterns of microbial colonization. A new interesting feature, the phagocytosis and intracellular destruction of microorganisms by the nephridial epithelial cells, has been observed in our laboratory for the first time. In Scheroteca savignyi minor, the phagocytic activity takes place in the bladder, the most distal region of the nephridium, next to the nephridiopore, which may prevent the microorganisms from entering the more proximal regions. In Octolasion cyaneum the microbes reach the striated duct, where they live in symbiosis, adhere to the cell's surface, and are engulfed and destroyed by the cells of the middle tubule - the more proximal, neighboring region. The phagocytosis and intracellular degradation of microorganisms probably lead to the massive formation of lamellar bodies, which are observed in these cells and in the neighboring ones.
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  • 72
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    Cell Motility and the Cytoskeleton 5 (1985) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 73
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    Cell Motility and the Cytoskeleton 5 (1985), S. 377-392 
    ISSN: 0886-1544
    Keywords: newt ; lung ; cilia ; beat frequency ; waveform ; models ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Highly coupled newt lung ciliated cell models were used to study the effects of MgATP concentration on ciliary beat frequency and waveform. Models were prepared from ciliated lung cells of the newt Taricha granulosa by trypsin dissociation of the epithelium, demembranation with Triton X-100, and reactivation with MgATP, as described previously [Weaver and Hard, 1985]. Beat frequencies were measured stroboscopically. Ciliary waveforms of reactivated models and intact mucociliary epithelial sheets were determined by single frame analysis of high-speed movies. Waveform parameters calculated included the durations of the effective and recovery strokes, the angular velocities of the ciliary base and tip, the position of the bend along the ciliary shaft during the recovery stroke, the velocity of recovery stroke bend propagation, and the ratio of the duration of recovery stroke bend propagation to the duration of the recovery stroke itself. We found that beat frequency varied biphasically in response to MgATP at 21°C, as shown previously for isolated, individual, newt lung axonemes. Apparent Fmax (maximum beat frequency) and Km values of 25 Hz and 0.14 mM, and 35 Hz and 0.47 mM, respectively, were obtained for each linear segment of the biphasic double reciprocal plot. Demembranation did not alter either ciliary waveform or the pattern of coordination. In this system, metachrony is antilaeoplectic and ciliary waveform appears to be regulated independent of beat frequency.
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  • 74
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    Cell Motility and the Cytoskeleton 5 (1985), S. 507-527 
    ISSN: 0886-1544
    Keywords: axonal transport ; microtubules ; organelles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A model for fast axonal transport is developed in which the essential features are that organelles may interact with mechanochemical cross-bridges that in turn interact with microtubules, forming an organelle-engine-microtubule complex which is transported along the microtubules. Computer analysis of the equations derived to describe such a system show that most of the experimental observations on fast axonal transport can be simulated by the model, indicating that the model is useful for the interpretation and design of experiments aimed at clarifying the mechanism of fast axonal transport.
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  • 75
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    Cell Motility and the Cytoskeleton 5 (1985), S. 53-60 
    ISSN: 0886-1544
    Keywords: calcium ; Chlamydomonas ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ca2+ has profound effects on the movement of cilia and eukaryotic flagella, including those of Chlamydomonas. Two clear changes seen in Chlamydomonas flagella with changes in Ca2+ are beat frequency and symmetry. Photographic and computer assisted analysis of flagellar bending patterns on a uniflagellate mutant of Chlamydomonas have been used to examine details of the effects of Ca2+ on the movement of ATP-reactivated, demembranated flagella. In addition to the forward mode bending pattern seen at low Ca2+ concentrations (10-9 M), which has a frequency of about 50 Hz and the reverse mode bending pattern seen at high Ca2+ concentrations (10-4 M) with a frequency around 70 Hz, we carefully examined bending patterns in the intermediate Ca2+ concentration range of 1-6.5 × 10-6 M. In this intermediate range, the bending patterns have significantly reduced asymmetry and slightly increased frequency, compared to the motility observed at low Ca2+ concentrations. These observations indicate that changes in these two parameters of motion do not occur in parallel and suggest that the effects of Ca2+ may be a multicomponent process. Physiologically, these changes in the beat pattern at intermediate Ca2+ may signal either (1) the beginning stages of transition to the symmetrical, high-frequency beating seen at high Ca2+, or (2) a more normal forward mode motility for the trans flagellum as suggested by Kamiya and Witman [1984]. No large amplitude bending patterns associated with transitions between forward and reverse mode beating in intact cells were seen at the intermediate Ca2+ concentrations.
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  • 76
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    Cell Motility and the Cytoskeleton 5 (1985), S. 31-51 
    ISSN: 0886-1544
    Keywords: microtubules ; birefringence ; flow birefringence ; tubulin ; polarization microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Understanding the molecular basis of mitotic movements in living cells will require correlative experiments on intact cells, cell models, purified tubulin, and perhaps other biopolymers. Birefringence is one assay that is useful in all of these experimental situations. Heretofore, studies of birefringence changes during mitosis have lacked a quantitiative basis for interpretation in terms of microtubule number and packing density. One of the aims of this work was to establish that relationship.Purified calf brain tubulin was polymerized to equilibrium and oriented in the hydrodynamic field of a microcapillary flow birefringence apparatus. The relationship between birefringence and microtubule packing density was determined by a combination of optical, electron microscopic, and biochemical methods. The data correlate surprisingly well with those obtained by others from in vitro measurements on isolated mitotic spindles. Using the flow birefringence data, the sensitivity of polarizing microscopes for detecting microtubules was examined and found to depend on microtubule packing density, object thickness, and instrumental factors that limit both the detection and measurement of weakly birefringent objects. Because of the dependence of measurement sensitivity on object thickness, a method of measuring the thickness of microtubule bundles using the dispersion of birefringence was developed. This method is capable of measuring thickness to within two or three Airy diffraction units and does not require any assumptions regarding object symmetry.
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  • 77
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    Cell Motility and the Cytoskeleton 5 (1985), S. 225-237 
    ISSN: 0886-1544
    Keywords: neural crest ; migratory behavior ; microfilaments ; stress fibers ; tractional force ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated one aspect of the migratory behavior of quail neural crest (NC) cells by comparing the organization of microfilament bundles and the ability to distort migratory substrata by NC, somite, and notochord cells in vitro. In contrast to the numerous cytoplasmic stress fibers in somite-derived fibroblasts and notochord cells revealed by rhodamine-phalloidin staining and thin-section electron microscopy, microfilaments in NC cells are restricted to the cell cortex. To test the relative degrees of tension generated by these cell types on the underlying substratum, cells were cultured in collagen gels and on distortable silicone rubber sheets. Explanted somites and notochords produced dramatic radial alignment of 750 μg/ml collagen gels, whereas neural crest cells only aligned gels of lower concentrations. Fibroblasts did not migrate individually from explanted somites and notochords into 250 μg/ml collagen gels as readily as into higher concentration collagen lattices. In contrast, neural crest cells migrated into matrices of low concentration as well as into higher concentration collagen gels. Neural crest cells and their pigmented derivatives did not distort silicone rubber sheets, whereas somite and notochord-derived fibroblasts wrinkle this substratum after 4 days in culture. Thus, the differences in organization of the actin cytoskeleton reflect the tractional force exerted by these cells on their substratum. We hypothesize that the migratory behavior of NC cells in vivo may be related to their ability to translocate through embryonic extracellular matrices while generating relatively weak adhesions with the substratum, whereas the stronger forces generated by other embryonic cell types upon the delicate extracellular matrix may restrict their migration and may be associated with other morphogenetic events.
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  • 78
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    Cell Motility and the Cytoskeleton 5 (1985), S. 239-249 
    ISSN: 0886-1544
    Keywords: tektins ; microtubules ; flagella ; cilia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Affinity-purified antibodies against Strongylocentrotus purpuratus sperm flagellar tektin polypeptides have been tested for cross-reactivity with microtubules isolated from various sources, using indirect immunofluorescent staining and antibody binding to nitrocellulose replicas of SDS polyacrylamide gels. The antitektins reacted with sperm tail axonemes from four genera of sea urchins and with cilia from sea urchin embryos. Antibody binding was observed only if the specimens were prefixed by methods that would not preserve them well at an ultrastructural level. However, even after such fixation regimes, no antibody binding was detected to cytoplasmic microtubule arrays in the same embryos, to mitotic spindles isolated from sea urchin or to gill cilia from a mollusc. We conclude that, if tektins are present in sea urchin egg cytoplasmic microtubules, they are sufficiently different from the sperm tektins to have no common strongly antigenic determinants.
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  • 79
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    Cell Motility and the Cytoskeleton 5 (1985), S. 323-331 
    ISSN: 0886-1544
    Keywords: Tetrahymena ; cell model ; ATP concentration ; Ca sensitivity ; backward swimming ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using Tetrahymena pyriformis, strain w, and Tetrahymena thermophila, B-1868, we prepared cell models that showed ciliary reversal with change in Ca-ion concentration, as was also noted for the Paramecium cell model. No differences could be found between these two strains in the reactivation state, and their response to environmental conditions was essentially the same. The reactivation rate was 90% or more. Swimming velocity of the cell model was found to be 200 ± 49 μm/sec at 25.0°C ± 0.5°C, while the velocity for the living cells was 527 ± 101 μm/sec. Swimming velocity with change in environmental conditions, such as pH, Mg-ATP, and Ca-ion concentrations, was studied. Compared to the cell model of Paramecium, the Tetrahymena cell model had higher sensitivity toward Ca-ion in the reactivation medium. The effects of chlorpromazine, and inhibitor of calmodulin, on the swimming behavior of the cell models were studied.
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  • 80
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    Cell Motility and the Cytoskeleton 5 (1985), S. 431-446 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubules assembled from sea urchin eggs with the use of taxol contain a 77,000-dalton protein as the major nontubulin component [Vallee and Bloom (1983): Proc Natl. Acad. Sci. U.S.A. 80:6259-6263]. We have raised five monoclonal antibodies to this protein to aid in its characterization. Immunoblot analysis of the sea urchin microtubule purification fractions indicated that the protein copurified quantitatively with microtubules. All five antibodies stained the mitotic spindle of dividing sea urchin eggs by immunofluorescence microscopy, indicating that the protein was a component of the mitotic spindle and suggesting that it was actually localized on microtubules in vivo. Immunofluorescent staining of higher resolution was observed in a subpopulation of the coelomic cells found in adult sea urchins, confirming that the 77,000-dalton protein is indeed present on microtubules in vivo. Because taxol was not used for the immunofluorescence experiments, we conclude that the microtubule-associated protein (MAP)-like behavior of the 77,000-dalton protein in vitro was not induced artifactually by taxol. To determine whether this protein is a component of sea urchin microtubules in general, cilia obtained from blastula stage embryos and sperm tail flagella were analyzed with the antibodies. The protein was undetectable by both immunoblot analysis and immunofluorescence microscopy in both preparations of axonemal microtubules. These results indicated that the 77,000-dalton MAP is restricted to cytoplasmic and mitotic microtubules in the sea urchin. Furthermore, in view of its particular abundance in embryos, whose microtubules are devoted substantially to mitosis, the 77,000-dalton MAP is likely to play an important role in regulating the activity of mitotic spindle microtubules in the sea urchin.
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  • 81
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    Cell Motility and the Cytoskeleton 5 (1985), S. 463-473 
    ISSN: 0886-1544
    Keywords: sponge dissociates ; cell migration ; time-lapse analysis ; cell aggregation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The production of both lamellipodia and peculiar thin protuberances (scleropodia) characterizes the preaggregative motility of cells after dissociation of the sponge Clathrina.The locomotory paths taken by cells before aggregation were recorded by time-lapse microcinematography. Changes of direction in successive 50-s time intervals and 50-s mean velocities of each cell were both taken into account as statistical variables. Their distributions give probability density curves that seem to fit bilateral exponential functions. The analysis of the angles of turn indicates a tendency for the cells to persist in their direction of motion and to make counter-clockwise turns. Implications of such in vitro cellular behaviors in aggregative and in vivo processes are suggested.
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  • 82
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    Cell Motility and the Cytoskeleton 5 (1985), S. 355-375 
    ISSN: 0886-1544
    Keywords: Newt ; lung ; cilia ; cell models ; ciliary coordination ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Demembranated ciliated cell models are useful for studying mechanisms responsible for the regulation of ciliary coordination and waveform. This paper describes procedures for isolating ciliated cells from the newt, Taricha granulosa, by trypsin dissociation, their subsequent demembranation by Triton X-100, and their reactivation with MgATP to produce highly motile, coordinated, ciliated cell models. Reactivation of cell models with a high degree of mechanochemical coupling depended on avoiding mechanical damage and maintaining optimal conditions during all stages of isolation and reactivation. Highly motile models were prepared from cells incubated in trypsin, treated briefly with EDTA, separated by gentle agitation, and concentrated by centrifugation at low gravitational forces. Optimal demembranation and reactivation conditions were similar to those described previously for isolated newt lung axonemes. Under these conditions, nearly 100% of the models were reactivated when provided with MgATP and 90-95% beat with coordinated waves. The ciliary tufts beat at frequencies within the range measured in living cells and their reactivated motility was stable for at least 30 min at constant MgATP. These highly coupled models were used to show (1) that development of coordination in the ciliary tuft occurs at a higher substrate concentration range (10-25 μM) than that required to initiate motility per se (2-10 μM); (2) that outer dynein arms may not contribute to beat frequency at substrate concentrations below 35 μM; and (3) that vanadate has effects both on beat frequency and coordination of the tufts.
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  • 83
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    Cell Motility and the Cytoskeleton 5 (1985), S. 415-430 
    ISSN: 0886-1544
    Keywords: Actin ; immunofluorescence ; NBD-phallacidin ; Chlamydomonas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have localized actin in gametes of Chlamydomonas reinhardi by two approaches: (1) indirect immunofluorescence with an affinity-purified antibody and (2) staining with NBD-phallacidin, a fluorescent reagent that binds only to F-actin [Barak et al, 1980, Proc Natl Acad Sci, 77:980-984]. Staining of either mating type “plus” (mt+) or “minus” (mt-) gametes with antiactin antibody resulted in similar fluorescent images: most of the actin was located peripherally along the lateral and posterior aspects of the cells. There was diffuse staining centrally, but the flagella did not stain. No brightly stained spot was observed near the mt+ mating structure, the site where the fertilization tubule elongates with concomitant polymerization of actin [Detmers et al, 1983, J Cell Biol, 97:522-532]. Gametes stained prior to mating with NBD-phallacidin showed no fluorescence above background, indicating that there were no concentrations of F-actin in these cells. This suggested that the cytoplasmic staining observed with antiactin represented primarily a nonfilamentous form of the protein. In mating gametes staining with NBD-phallacidin was detected only in the fertilization tubule, indicating that this was the only dense accumulation of filamentous actin within the cells. Mating gametes stained with antiactin antibody exhibited cytoplasmic fluorescence that was slightly more punctate than prior to mating, and the fertilization tubule was brightly stained. Our observations suggest that the site-specific polymerization of actin within the fertilization tubule occurs in the absence of a concentrated pool of actin subjacent to the mating structure.
    Additional Material: 9 Ill.
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  • 84
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    Cell Motility and the Cytoskeleton 5 (1985), S. 475-489 
    ISSN: 0886-1544
    Keywords: digital image processing ; flagella ; cilia ; bends ; Hemicentrotus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A novel method of digital image analysis of the bends of eukaryotic flagella and cilia was devised. In the analysis system, all image pixels were systematically extracted and processed to measure angular direction and curvature. Simulation experiments on theoretical model pictures of flagella with sine-generated or arcstraight line bending waves demonstrated that the method can be used with considerable high accuracy. This method then revealed abrupt changes in slope of the curvature in sperm flagella and embryo cilia of the sea urchin, Hemicentrotus pulcherrimus. This indicates that the digital image processing used may be helpful in the study of flagellar and ciliary movements.
    Additional Material: 7 Ill.
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  • 85
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    Cell Motility and the Cytoskeleton 5 (1985), S. 333-350 
    ISSN: 0886-1544
    Keywords: eel sperm ; 9+0 flagellum ; motility ; helicoidal bending ; reactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sperm flagella of the eel, Anguilla anguilla, are capable of vigorous motion in spite of having an axoneme with reduced structure that lacks the outer dynein arms, radial spokes and spoke heads, the two central tubules and the central tubule projections that are all part of the standard “9+2” axoneme. These sperm progress forward rapidly as a result of the propagation of helicoidal waves distally along the flagellum. Their flagellar beat frequencies are high, 93 Hz at 21°C, and they roll at a frequency of about 19 Hz. Eel sperm could be demembranated with Nonidet P-40 and reactivated with MgATP2- in 0.22 M K acetate at pH 8.1. The reactivated motility closely resembles that of the live sperm, with a beat frequency of 69 Hz, but the demembranated flagella are unusually fragile, and commonly disintegrate by a combination of splitting, coiling, and sliding within a few minutes. Little reactivation is obtained if acetate is replaced by Cl- in the reactivating medium. The Michaelis constant for beat frequency (0.2 mM) is similar to that obtained for several “9+2” flagella. These sperm, however, appear to lack the mechanism by which Ca2+ regulates waveform. Our results indicate that eel sperm flagella, which at rest are straight, are induced to bend helicoidally by ATP, as the result of sliding between tubules that is blocked at both the base and tip of the organelle. The flagellar waveform consists of a series of planar bends separated by short regions of right-handed twist, which give it an overall left-handed helicoidal form.
    Additional Material: 9 Ill.
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  • 86
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    Cell Motility and the Cytoskeleton 5 (1985) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 87
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    Cell Motility and the Cytoskeleton 5 (1985), S. 491-506 
    ISSN: 0886-1544
    Keywords: Somitogenesis ; neurulation ; alpha-actinin ; morphogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A discrete stage in two different morphogenetic processes has been examined employing fluorescently labelled alpha-actinin as a probe to localize native alpha-actinin and antibodies to localize fibronectin and collagen type I. The stage of somitogenesis examined is the transition from the compact mesenchymal somitic mass to the epithelial somitic vesicle (ie, epithelialization of the somite). The stage of neurulation examined is the transition from the relatively flat neuroepithelium to the approximation of the neural folds. Before these morphogenetic movements begin, the neuroepithelium is sitting upon a basal lamina and interstitial collagen, and the somite is surrounded by a meshwork of interstitial collagen. During both of these processes, the cells become narrowed at their apices in the region of the tissue that is becoming concave, and alpha-actinin is localized in the apices. The localization of intracellular alpha-actinin and extracellular fibronectin, and the distribution of collagen, suggest that there is a coordinated appearance and distribution of these molecules that is temporally associated with these discrete morphogenetic events.
    Additional Material: 6 Ill.
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  • 88
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    Cell Motility and the Cytoskeleton 5 (1985), S. 17-29 
    ISSN: 0886-1544
    Keywords: cell motility ; membrane recycling ; immunofluorescence microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mouse peritoneal macrophages subjected to gradients of activated mouse serum were found by immunofluorescence observations to have their Golgi apparatus and their microtubule-organizing center largely oriented in the direction of the gradient. By analogy with similar results obtained with motile fibroblasts, it is proposed that these two organelles are rapidly and coordinately reoriented inside the macrophages in order to direct the insertion of new membrane mass, via vesicles derived from the Golgi apparatus, into the leading edge of the cell. Consistent with the importance of such membrane insertion to cell migration, we found that the ionophore monensin, an inhibitor of Golgi functions, inhibited cell motility in the chemostactic gradient. It was further shown that several inhibitors of chemotaxis (monensin, cytochalasin D, cycloheximide) did not inhibit the reorientation of the Golgi apparatus/microtubule-organizing center in cells exposed to a chemotactic gradient, and that the reorientation required extracellular Ca+2.
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  • 89
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    Cell Motility and the Cytoskeleton 5 (1985), S. i 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 90
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    Cell Motility and the Cytoskeleton 5 (1985), S. 103-122 
    ISSN: 0886-1544
    Keywords: gliding ; cell motility ; cytoskeleton ; diatoms ; capping ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gliding motility was investigated in the marine diatom, Amphora coffeaeformis. Ultrastructural, biochemical, and pharmacological protocols were employed to probe the possible involvement of cytoskeletal proteins and a secretory process in gliding motility. Motility rate was measured using a video recording apparatus, and the effects of various cytoskeleton-disrupting drugs on motility were tested. Cytochalasins D and E, podophyllotoxin, and vinblastine (all at 25 μUg/ml) reversibly inhibited motility, as did monensin (10 μUM) and pronase (25 μUg/ml). Biochemical protein analysis of whole-cell extracts by one- and two-dimensional polyacrylamide gel electrophoresis revealed polypeptides comigrating with rabbit skeletal muscle actin and bovine brain tubulin; however, specific assays used to separate actin from whole-cell preparations gave ambiguous results. Ultrastructural studies revealed the presence of extracellular material between the raphe canal and the substratum in motile cultures. An assay was devised for the detection of radioactively labeled material (MW 〉 1800 Daltons) released by motile cultures into the culture medium. When cultures were treated with either an anticytoskeletal drug or monensin, motility was inhibited while the amount of measured radioactivity increased over solvent-treated control groups. The results from this study indicate possible roles for both actin- and tubulin-based structures in gliding motility of Amphora. Though secretion may be necessary for gliding to occur, its exact relationship to motility was not deduced. The data obtained in this study are compatible with a theory for the mechanism of gliding which involves the surface translocation of externally exposed membrane proteins against an immobile matrix of substratum-attached secreted material to generate the force required for movement.
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  • 91
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    Cell Motility and the Cytoskeleton 5 (1985), S. 195-208 
    ISSN: 0886-1544
    Keywords: central pair ; radial spoke ; flagella ; mutant ; Chlamydomonas ; suppressor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flash photomicrography at frequencies up to 300 Hz and computer-assisted image analysis have been used to obtain parameters describing the flagellar bending patterns of mutants of Chlamydomonas reinhardtii. All strains contained the uni1 mutation, to facilitate photography. The radial spoke head deficient mutant pf17, and the central pair deficient mutant, pf15, in combination with suppressor mutations that restore motility without restoring the ultrastructural or biochemical deficiencies, both generate forward mode bending patterns with increased shear amplitude and decreased asymmetry relative to the “wild-type” uni1 flagella described previously. In the reverse beating mode, the suppressed pf17 mutants generate reverse bending patterns with large shear amplitudes. Reverse beating of the suppressed pf15 mutants is rare. There is a reciprocal relationship between increased shear amplitude and decreased beat frequency, so that the velocity of sliding between flagellar microtubules is not increased by an increase in shear amplitude. The suppressor mutations alone cause decreased frequency and sliding velocity in both forward and reverse mode beating, with little change in shear amplitude or symmetry.
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  • 92
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    Cell Motility and the Cytoskeleton 5 (1985) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 93
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    Cell Motility and the Cytoskeleton 5 (1985), S. 267-292 
    ISSN: 0886-1544
    Keywords: mammalian cilia ; respiratory tract ; mucociliary clearance ; laterofrontal cirri ; Mytilus edulis ; beat cycle ; computer analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The beat cycles of rabbit tracheal cilia in culture and Mytilus laterofrontal cirri were recorded using a phototransistor, transillumination, video, and phase-contrast microscopy. The photoelectronic signal and video image of the ciliary activity were simultaneously recorded as a composite image. The photoelectronic signal was converted into a digital signal by a data acquisition system for further computer processing.By the selection of a small detector area and accurate detector alignment, a simple, repetitive photoelectronic signal representing ciliary activity was obtained. This signal records the ciliary beat frequency and demonstrates the triphasic nature of the beat cycle. The photoelectronic signal can be precisely correlated with the ciliary activity by analysis of the composite video recordings to provide the duration of the effective, recovery, and rest phases of the beat cycle. The videophotoelectronic signal correlations were verified by high-speed cinematography. High-speed films of ciliary activity were digitized, and the image density of selected pixels was analyzed by computer with respect to time and ciliary motion.These studies indicate that duration of the phages of the beat cycle are differentially reduced with increased beat frequency; the effective phase duration was quickly reduced to a minimum. This was followed by the reduction of the duration of the recovery phase to a minimum. The rest phase continues to be reduced without reaching a minimum, over the range of beat frequencies observed. These results suggest that ciliary beat frequency may be regulated either by modifying the rates of dynein-microtubule interactions or the rate of transition from one beat phase to the next.
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  • 94
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    Cell Motility and the Cytoskeleton 5 (1985), S. 311-322 
    ISSN: 0886-1544
    Keywords: Spectrin ; TW 260/240 ; chicken intestinal brush border ; actin assembly ; actin filament cross-linking ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: TW 260/240 is a tissue-specific spectrin found in the terminal web region of the chicken intestinal bruish border. We have examined the effects of TW 260/240 on assembly rates and critical concentrations (Co's) for monomer addition at the barbed and pointed ends of the actin filament. For these studies, acrosomal processes (AP) from Limulus sperm were used as nuclei for actin assembly. Under conditions which favor the interaction of TW 260/240 for actin (20-75 mM KCl, 2 mM Mg++) no effect on either elongation rates or Co's at either end of the actin filament was observed in the presence of this spectrinlike protein. The Limulus AP nucleation assay also allowed visualization of the kinetics of filament binding and cross-linking by TW 260/240. Ultrastructural analysis of TW 260/240 binding to actin filaments at their growing ends indicates that TW 260/240 tetramers bind laterally to the filament. Finally, evidence is presented that indicates that filaments cross-linked by TW 260/240 are stabilized against shear-dependent breakage.
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  • 95
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    Cell Motility and the Cytoskeleton 5 (1985), S. 137-173 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 96
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    Cell Motility and the Cytoskeleton 5 (1985) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 97
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    Cell Motility and the Cytoskeleton 5 (1985), S. 209-224 
    ISSN: 0886-1544
    Keywords: flagellar dynein ; cyclic nucleotides ; sperm activation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Methods of demembranation and reactivation of Lytechinus pictus sperm were developed that result in non-motile sperm which take on a stable bend of about 3.5 radians at the proximal end of the cell. The middle and distal portion of the flagellum is relatively straight or slightly bent in the same direction forming a somewhat “C” shaped sperm cell. In these studies, we refer to this characteristic shape as the quiescent form, and as opposed to “rigor wave” sperm, the quiescent form is induced and maintained by a relatively high concentration of MgATP2- (〉 0.2 mM). Other conditions important to the production and maintenance of the quiescent form in demembranated sperm include: starting with concentrated, undiluted sperm, maintaining low Ca++ in the demembranation buffer, using a minimum of 0.2 mM MgATP2- and pH of 7.9-8.1 in the reactivation buffer. Deviation from some of these conditions results in a dramatic increase in motile, asymmetrically beating sperm. Addition of 0.4 mM CaCl2 to the reactivation buffer increased the proximal bend angle to 5 radians. The induction and maintenance of the stationary bend is mediated by dynein activity: “rigor wave” sperm were transformed to the quiescent form upon 0.2 mM ATP addition; micromolar vanadate abolished the quiescent form by “relaxation” of the proximal bend; and the vanadate relaxed sperm were restored to quiescent form by catechol. Importantly, 20 μM cAMP activated motility of the otherwise quiescent-form sperm. Quiescent-form, demembranated sperm were also activated by mild trypsin digestion. These and other data suggest that the quiescent-form sperm are trapped at the end of the principal bend, and these data are consistent with the proposal that the single stationary bend results from asymmetry of active microtubule sliding [Gibbons and Gibbons, (1980): J. Cell Biol. 84:13-27].
    Additional Material: 5 Ill.
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  • 98
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    Cell Motility and the Cytoskeleton 5 (1985), S. 175-193 
    ISSN: 0886-1544
    Keywords: primary cilia ; connective tissues ; secretory organelles ; extracellular matrix ; cybernetic probe ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: More than 300 primary cilia have been identified electronmicroscopically in a variety of embryonic and mature connective tissue cells. To further define the enigmatic function of these cilia, we examined the interrelationships between the basal apparatus and cytoplasmic organelles and the ciliary shaft and the extracellular matrix. The basal diplosome was consistently associated with the secretory organelles including the maturing face of the Golgi complex, Golgi vacuoles and vesicles, the microtubular network, the plasma membrane, and coated pits and vesicles. Small vesicles and amorphous granules were also observed within the ciliary lumen and adjacent to the ciliary membrane. Microtubule-membrane bridges linked axonemal tubules to the ciliary membrane. The position, projection, and orientation of the axoneme were influenced by the structural organisation and mechanical properties of the matrix and frequently caused angulation of the ciliary shaft relative to the basal body. Located midway between the secretory apparatus and the extracellular matrix, primary cilia would appear ideally situated to mediate the necessry interaction between the cell and its surrounding environment prerequisite to the formation and maintenance of a functionally effective matrix. We propose that primary cilia in connective tissue cells could act as multifunctional, cellular cybernetic probes, receiving, transducing, and conducting a variety of extrinsic stimuli to the intracellular organelles responsible for effecting the appropriate homeostatic feedback response to changes in the extracellular microenvironment.
    Additional Material: 17 Ill.
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  • 99
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    Cell Motility and the Cytoskeleton 5 (1985), S. 265-265 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
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  • 100
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    Cell Motility and the Cytoskeleton 5 (1985), S. 61-75 
    ISSN: 0886-1544
    Keywords: dynein ; erythro-9-[3-2-(hydroxynonyl)]adenine (EHNA) ; ATPase ; inhibition ; axoneme ; cytoplasm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In current purification strategies, affinity for microtubules or calmodulin is used to identify and purify cytoplasmic dynein-like ATPase from cell-free extracts of unfertilized sea urchin eggs. However, affinity purification procedures, though they define dynein-like ATPase activity, have not yet proven to be quantitative. An alternative purification strategy capable of producing a high yield of enzyme would require a specific assay in order to monitor cytoplasmic dynein purity at each step.In this study, we make a detailed comparison of the effects of EHNA on 22 different ATP-metabolizing enzyme activities, including 13 Mg++-ATPases. We isolate cytoplasmic dynein-like ATPase activity from three species of sea urchin eggs and sperm and show by means of dose-response curves that their sensitivities to inhibition by EHNA are very similar to one another. We demonstrate further that the EHNA dose-response characteristics of fourteen other ATP-metabolizing enzyme activities, including seven nondynein Mg++-ATPases, differ quantitatively from those of dynein-like ATPases.In studies of three other agents (vanadate, Ca++/calmodulin, and Triton X-100), we find that dynein-like ATPases vary by two orders of magnitude in their sensitivities to inhibition by vanadate, and little or no stimulation by either Ca++/calmodulin or Triton X-100 is seen. Our results suggest that inhibition by EHNA is a universal and specific property of dynein-like ATPases, which ultimately should prove useful in the quantitative purification and characterization of cytoplasmic dynein-like ATPase (s).
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