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  • Cell & Developmental Biology  (581)
  • Analytical Chemistry and Spectroscopy
  • Humans
  • 1935-1939  (581)
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  • 11
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flexures in the flexed-tailed mouse consist of unilateral fusions of adjacent vertebrae. Fusions, if complete, produce straight stiff segments.In normal mouse embryogeny, the precartilage cells surrounding the developing nucleus pulposus of the embryonic intervertebral disk in the proximal tail region begin to elongate and become fiber-like at about 14 days after fertilization. In the flexed mouse, such differentiation fails to take place on one side of an affected disk, and these cells develop through cartilage to bone. At such a point there is frequently a bend in the notochordal axis. Other abnormalities of the notochord have been observed. These are not the cause of the flexures.The gene for flexed tail also produces two effects more general in their expression. First, it slows the growth of the vertebral column as indicated by the shorter vertebrae of the proximal tail region. This is observable 13 days after fertilization. Second, it produces an embryonic anemia which is already in existence at 14 days after fertilization. It is postulated that the flexures are due to the retardation of growth at a time which is critical for the intervertebral disks. Whether this retardation is the primary effect of the gene and produces the anemia, or whether the anemia is primary and produces the retardation, the data do not show.
    Additional Material: 3 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 279-284 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histological structure of the eye of the monotreme, Echidna hystrix is described with reference to its comparative relationships. The eye is primarily mammalian in character but its choroid contains a definite cartilaginous plate and its retina is anangiotic.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 58 (1935), S. 555-571 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each contractile vacuole system of Paramecium multimicronucleata is made up of a number of components, some temporary and others permanent. The contracting vacuole with its membrane is a temporary structure as are the vesicles which fuse to form it. The vacuole discharges its contents to the exterior leaving a vestige closing the pore. The pore, with its discharging tubule and the feeding canals are permanent cell organelles. The feeding canals end in injection tubules which extend up to the pore. The vesicles, which later fuse to form the vacuole, are formed at the proximal end of the injection canals, leaving a membrane closing the canal, much as a food vacuole is formed at the gullet. The canal-fed contractile vacuole of Paramecium is very similar to the vesicle-fed vacuole of Euplotes both as to its origin and its fate. The Nassonov homology is rejected.
    Additional Material: 8 Ill.
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  • 14
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paramecium caudatum becomes much elongated upon centrifuging at 21,000 times gravity. The chromatin is sometimes forced from the achromatic matrix of the macronucleus. The materials in the cell are redistributed according to their relative specific gravities as follows: At the centrifugal end of the cell, crystals, layer of fluid, micronucleus and macronuclear chromatin, food vacuoles and neutral red inclusions, achromatic matrix of the macronucleus, endoplasm with large clear alveoli, and fat, at the centripetal end of the cell. The contracting vacuole is displaced sometimes but not the feeding canals or pore. In some cases the crystals, micronucleus and macronuclear chromatin may be extruded from the cell. Animals which survive centrifuging regain their usual shape and the disturbed materials return to their usual distribution rapidly. Sometimes the crystals remain in large compact masses and are so passed to the daughter cells upon fission. The two components of the macronucleus do not fuse the macronuclear chromatin regenerates an achromatic matrix, and division is somewhat delayed. The old macronuclear matrix persists over a long time and sometimes interferes with division. Animals which have no micronucleus may survive and divide, but no amicronucleate races have been established. Apparently macronuclear chromatin is necessary for the survival and division of P. caudatum; in the absence of the macronuclear chromatin no replacement occurs from the micronucleus. The membrane of the contracting vacuole is temporary.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936) 
    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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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936), S. 1-10 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paraphysis of adult Amblystoma is made up of low columnar ependymal epithelit m which forms the paraphyseal tubules which end blindly and which communicate with one another by a common mouth with the third ventricle. Between the paraphyseal tubules venous sinusoids anastomose freely with one another forming a complicated rete. The sinusoids are made up entirely of endothelium. The blood supply to the paraphysis is entirely venous.Mitochondria were found in great abundance in the paraphysis of one female just previous to laying. Other specimens showed very few present. No conclusions can be drawn from these few observations as to the relationship between physiological activity and cellular structures.The Golgi apparatus was observed definitely localized between the nucleus and the ventricular end of the cell.Many large crystalloids were also observed to be localized between the nucleus and the ventricular end of the cell.Intercellular spaces are readily observed in sections stained with Mallory's connective tissue stain. Nassonow's osmic acid technique for the Golgi apparatus and Benda's crystal violet and alizarin stain clearly bring out the intercellular canals. Acid fuchsin stained particles within the intercellular spaces are more abundant toward the sinusoids than the cavities of the paraphyseal tubules. The intercellular canals have not been seen to communicate with either the sinusoids or the cavities of the paraphyseal tubules in any of the preparations observed.
    Additional Material: 8 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936), S. 91-112 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increases in weight, total body length, and width and length of the head capsule of Japanese beetle larvae were studied. Since the progression factors decreased with succeeding molts and exhibited considerable variation it was concluded that Przibram's principle is inapplicable. Cells were counted in the mid-intestine and brain. Columnar cells of the mid-intestine were measured. The data show: (a) No increase in cell number occurs at the time of molting. (b) The progression in weight and length cannot be correlated with an increase in cell number. In the first instar the progression for increase in weight was 5.73; while for increase in cell number, it was 1.67 for the mid-intestine, and 1.19 for the brain. In the second instar, the corresponding figures were 5.24, 1.98 and 1.69. In the third instar average weight increased 3.18 times, but there was practically no increase in cell number. Thus, molting does not represent a definite increase in number of cells of the insect's body as suggested by Przibram and Megusar, and Bodenheimer's method of calculating cell divisions seems to have no factual basis. Increase in size of the larva is largely due to an increase in cell size. The ratio of increase in total cell volume of the columnar cells of the mid-intestine is approximately equal to the ratio of weight increase.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936), S. 123-161 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An atypical euchromosome, characterized by the large size and deep stainability of its chromomeres during the meiotic prophase, occurs in representatives of seven genera of Acridinae, viz., Chorthippus curtipennis, Euchorthippus pulvinatus, Stenobothrus lineatus, Omocestus ventralis, Stauroderus biguttulus, Gomphocerus rufus, and Aeropedellus clavatus. This element, which is termed the ‘megameric chromosome,’ stains more deeply than the other euchromosomes also during interkinesis and early spermiogenesis. The megameric chromosomes of the individual exhibit striking similarity in the number, size, and arrangement of their chromomeres through successive stages of the meiotic prophase. All the evidence from cytological study indicates that these chromosomes are intergenerically homologous. This is chiefly significant in the support it gives to the theory of chromosome individuality. The heteromorphic megameric tetrad of one individual of S. biguttulus - unequal because of a deficiency - usually undergoes segregation in the second division. The megameric chromosomes display splits previous to synapsis. Pairing begins at their proximal ends and proceeds distally. All the euchromosomes of the spermatid nucleus show splits in preparation for the first cleavage division of the zygote.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936), S. 215-223 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a comparative study of the branchial epithelium of fishes we find the occurrence of three distinct types and seven subtypes of intra-epithelial glands which are in intimate association with the branchial epithelium of fishes.These glands have been classified according to their morphological patterns, cytoplasmic content and other features dealing with structural complexity.Although these structures arrange themselves in a graded series which become increasingly more and more complex, there does not appear to be any definite correlation between the structural complexity of the glands, and the apparent evolutionary history of the fishes.We conclude from the characteristic arrangement, relationships, and specific staining reactions that these structures are intra-epithelial mucous glands.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 57 (1935), S. 473-499 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hypoglossal downgrowth is initiated at about the twenty-somite stage, as ventral extensions from the postotic (occipital) myotomes 3 and 4. At thirty somites, occipital myotomes 2, 3 and 4, and cervical 1 have developed ventral processes. These descending processes with contributions from posterior myotomes later form a common condensed area below myotomes 2 to 7, the submyotomic tract. There develops from this a cord of mesoderm, the hypoglossal cord or downgrowth.The anterior postotic myotomes are classed as indirect (numbers 1, 2, 6 and 7) or direct (numbers 3, 4 and 5) contributors to the hypoglossal downgrowth.Mechanical factors associated with this growth process are discussed.The hypoglossal nerve at 75 hours has six roots, four occipital (numbers 1 to 4) and two cervical. The first two occipitai roots fail to keep pace in development and are subsequently lost. A transïtory connection of the third cervical to the hypoglossal nerve is demonstrated at the age of 5 days. At 6 days the first occipital root is reduced to scattered fibers, the remaining occipital roots, numbers 2 to 4, increase in size, cervicals 1 and 2 join the hypoglossa.The correspondence of the myotomes providing the contributions to the hypoglossal cord and the nerves providing the major contributing roots of the hypoglossal nerve is commented on.
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