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  • Life and Medical Sciences
  • 1970-1974  (17)
  • 1935-1939
  • 1972  (17)
  • 1
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The calcium uptake and ATPase activities of isolated sarcoplasmic reticulum were studied during the first six days of chick skeletal muscle maturation in tissue culture. Statistically significant increases in these activities were observed between the second and the sixth day of maturation. Increases in oxalate-dependent calcium uptake were demonstrated at concentrations of 2.5 × 10-5 M calcium and 10-4 M calcium. Calcium-binding determinations conducted in the absence of oxalate displayed changes manifested by an increase at day 5 followed by a significant decrease at day 6. Increases in total ATPase activity during maturation paralleled the sequential increases in calcium uptake. Calcium-stimulated ATPase activity, however, did not change significantly during periods of marked increase in calcium uptake, suggesting that these activities are dissociated during development of the sarcoplasmic reticulum. These data demonstrate that calcium uptake and total ATPase activity increase during muscle maturation in tissue culture and that these activities are present prior to spontaneous contractions.
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The response of unfertilized sea urchin eggs stimulated with continuous D.C. was studied using cinematographic techniques. As reported by previous workers, the initiation of the response was anodal in polarity and followed a typical strength-duration curve. However, the anodal response may be swelling and/or contraction, depending on the amplitude of the applied stimulus, i.e., the magnitude of the contraction is directly related to the applied stimulus and is a graded response. It is suggested that the phenomena of anodal swelling and anodal contraction represent a continuum of responses based on ion exchange.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 138 (1972), S. 375-385 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the electric organs of Gymnarchus niloticus has been studied and the origin and histogenesis of an electroplate worked out. A segmental origin of the electroplate is reported for the first time for this fish. Light has been thrown on many hitherto obscure phenomena, viz., growth of core girth, loss of transverse striations on the myofibrillar elements, differentiation of electroplate polarities, shortening in length of the electroplate etc. The transverse striations of the myofibrillar bundle of the electroplate primordium progressively disappear with development owing to splitting apart of the constituent myofilaments and consequent loss of their parallel order, and not to degeneration of the myofibrillar bundle. The excessive growth of the core girth of the electroplates is caused by the deposition of some kind of interfibrillar substance probably secreted by the peripheral cytoplasm.
    Additional Material: 14 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 137 (1972), S. 161-179 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hamster nasal cavity consists of vestibular, non-olfactory and olfactory portions. Much of the non-olfactory nasal cavity surface is lined by cuboidal, stratified cuboidal, and low columnar epithelia, devoid of cilia. Goblet cells and ciliated respiratory epithelium are present over only a small portion of the nasal cavity surface.The largest glandular masses in the hamster nose are the maxillary recess glands, the vomeronasal glands and the lateral nasal gland 1; these three glands contain neutral mucopolysaccharides (PAS-positive). Other nasal glands contain both acidic and neutral mucopolysaccharides; the staining reaction for acidic mucopolysaccharide is stronger in goblet cells and olfactory glands than in the other nasal glands.The ducts which open into the nasal vestibule are the excretory ducts of compound tubuloacinar serous glands. The one major PAS-positive gland whose duct opens into the nasal vestibule is the lateral nasal gland 1. The ducts of the compound tubuloacinar vomeronasal glands open into the lumen of the vomeronasal organ, which is connected to the ventral nasal meatus by means of the vomeronasal duct. The ducts of the branched tubuloacinar maxillary recess glands open into the maxillary recess. Few ducts open into the caudal half of the nasal cavity.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 138 (1972), S. 239-262 
    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 following eight major ossicle types is described and illustrated for the goniopectinid asteroid Ctenodiscus crispatus: terminal plates, superomarginal and inferomarginal ossicles, adambulacral and ambulacral ossicles, odontophores, oral intermediate plates, and superambulacral ossicles. Development, variation, and relationships with soft body-parts and with other ossicles are embphasized. Each ossicle type is distinguished by numerous structures related to its function and to articulation with adjoining skeletal elements. Because major structures (such as pustules, alveoli, and articulation surfaces) distinguishing ossicle types develop early during ontogeny, immature ossicles are readily identifiable. However, changes in form and orientation of these structures occur during ossicle growth. Ontogenetic changes are influenced by development of associated skeletal and soft parts. Ambulacral and adambulacral ossicles near the peristome are highly modified but retain the basic characteristics of structure and orientation which define these major types of skeletal elements.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 138 (1972), S. 407-431 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cephalic organ of presumed sensory function is described in nauplii and copepodids of the ascidicolous copepod Doropygus seclusus Illg. The receptor, located bilaterally in the anterodorsal head region, is composed of dendrites of extra optic protocerebral origin which have ciliary protrusions with basal bodies, no rootlets, and a basal infrastructure of the 9 + 0 type. The cilia do not branch and their distal terminations contain only one to four microtubules. In nauplii and free-living copepodids, a large epidermal supporting cell encapsulates the end of one dendrite and its cilia in a sac. Other dendrites and their cilia pass through the supporting cell and, terminally, the cilia escape to form a whorled fascicle which contacts the anterolateral cephalic cuticle. The latter end organ reaches its greatest development in the second copepodid stage  -  the stage which infects the ascidian. All of the symbiotic stages of the copepod have only a proportionately smaller end organ of the saccular type and apparently lack the end organ consisting of whorls of ciliary ends. The function of the receptor is unknown, but it is suggested that the end organ which disappears in the symbiotic stages functions in second copepodids in host recognition.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 136 (1972), S. 181-190 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cortical lobules of the avian kidney are branched structures in which the efferent venous system forms an intralobular axis. The latter receives portal blood through an intertubular capillary plexus. Capillary distribution is regionalized thus delimiting the boundaries of individual cortical lobules.The size of cortical lobules (combined length of individual branches) varies intraspecifically from less than 1 mm to more than 18 mm. The largest units are peripherally located in the dorsal and lateral aspects of the kidney, while smaller lobules are deeper within the renal mass. A system of naming the branches of the efferent venous drainage is described. Cortical lobules take origin at varied levels along this venous network.A typical cortical lobule provides collecting ducts and loops of Henle to several medullary lobules. The latter contact the cortical unit at intervals along its length, and each may be associated with more than one cortical lobule. Although boundaries are indefinite, a renal lobe can be regarded as a group of medullary lobules usually draining into a secondary ureteral branch plus their associated cortex.
    Additional Material: 9 Ill.
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the integument of the aquatic mite Arrenurus major Marshall is presented. When the cuticle is examined with the unaided eye and the light microscope, it appears to possess numerous tiny pits. However, scanning electron micrographs of the cuticle reveal that it is a solid surface with topographical sculpturing of the epicuticle, indicating that the “pits” are an internal phenomenon. In cuticle which has been sectioned, areas devoid of cuticular material beneath the thin exocuticle are revealed. These areas are the pits which are goblet-shaped.The integument consists of five major strata. These are from the outside to the inside: (1) a superficial layer with a maximum observed thickness of 725 Å, (2) an epicuticle with a thickness of about 900 Å and composed of at least four sublayers, (3) an exocuticle with a thickness of about 1.5 Å. Fibers of the exocuticle are arranged in a Bouligand pattern and exhibit a regularly occurring discontinuity with a spacing of 200 Å. (4) An endocuticle ranging from 15 to 20 μ in thickness. The endocuticle is characterized by bandings which superficially resemble the lamellae of insects but are not homologous, microfibers which exhibit a preferred orientation, and the presence of the pits; and (5) an epidermis lying beneath the endocuticle and extending into the pits.Pore canals are present only in the exocuticle and have their origin at the apices of the pits. The pore canals contain a central filament, and a plug is present just beneath the epicuticle.
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  • 9
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report presents light microscopic descriptions of lymphoid organs and aggregates in the snapping turtle Chelydra serpentina. The thymus and spleen were found to be similar to those of other ectothermic vertebrates. Certain gut associated lymphoid aggregates suggest the presence of reptilian equivalents of tonsils, Peyer's patches and the avian bursa of Fabricius. Lymphoid aggregates located in the axillary and inguinal regions were apparent for the first time in an ectothermic vertebrate. These are of particular interest since they may represent ancestors of true lymph nodes in analogous locations in mammals. It is concluded that the snapping turtle is not deficient in lymphoid tissue, although there is a conspicuous absence of typical germinal centers, characteristic of mammalian organs.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 80 (1972), S. 299-312 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Improvements have been made in methods of preparation of single cell suspensions from mouse testes for separation by sedimentation at unit gravity. Mechanical means of preparation specifically damage spermatogonia, young primary spermatocytes, and spermatids at various stages of development, resulting in apparent sedimentation velocities which correspond closely to those of free nuclei. Trypsin has been used to release these cells from the seminiferous tubules allowing measurement of the sedimentation properties of the intact cell. The exclusion of trypan blue from the cells, resistance to trypsin, and the persistence in vitro of the highly differentiated forms of macromolecular synthesis demonstrate the integrity of the cells in the suspensions prepared with trypsin. Differentiation pathways in terms of sedimentation velocities of the cells and nuclei have been constructed and are in agreement with morphological changes.
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