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  • GEOPHYSICS  (734)
  • Life and Medical Sciences  (679)
  • 2000-2004
  • 1980-1984  (1,309)
  • 1950-1954
  • 1935-1939  (104)
  • 1981  (1,309)
  • 1937  (104)
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  • 2000-2004
  • 1980-1984  (1,309)
  • 1950-1954
  • 1935-1939  (104)
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  • 1
    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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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 317-324 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The last muscle in the transverse superficial throat series in all genera of salamanders is here called ‘gularis.’ This eliminates a long list of synonyms. A description of its metamorphic changes in Dicamptodon (Ambystomidae) and comparison of the larval and adult conditions in this genus with those in other known genera clears up the homologies of the muscle throughout the series. The study is based on dissections and a survey of the literature covering all important groups except the Hynobiidae.
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  • 3
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 379-391 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The skull, mandible, atlas, scapula and the six long bones from seventy-four male and sixty-nine female skunk skeletons were weighed. Nine dimensions of the skull, two dimensions of the mandible and of the scapula, the length of the os coxa and the lengths of the same six long bones, were measured from 99 male and 109 female skeletons.The weights of the skull and of the nine bones are significantly heavier in the male skunks and all but one of the linear measurements are likewise significantly greater in the males. The weights and the linear dimensions of the skull and the mandible are more variable in the males but the lengths of the long bones are more variable in the females.The rather high positive correlations of the skull weight and the weights of the other parts of the skeleton studied, show that the weight of the skull is a good criterion of the weights of the other bones. These correlations are slightly higher in the males. The nineteen linear dimensions are likewise well correlated with the skull length. They average somewhat higher in the females.The data on the symmetry of the paired bones are not very conclusive, but there is a preponderance of heavier and longer right bones and a crossed symmetry is suggested.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 407-443 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Mexican scorpion Centruroides shows exactly the same type of chondriokinesis (by ring formation) as that hitherto known only in the related form Centrurus, as earlier reported by one of us ('31). The Golgi bodies show no trace of ring formation but are distributed by random assortment like that of the chondriosomes in other scorpions. The Golgi bodies, clearly visible in vivo, show the typical plate-like or lamellar structure characteristic of them in other forms. In the first division, after Weigl, there appear to be two metaphase stages, an earlier one in which the dictyosomes are irregularly scattered and a later one in which they tend to mass near the mitotic poles. In the same division, after Champy-Kull, the (presumable) dictyosomes are regularly massed near the poles and may be traced through the whole mitosis. The neural red bodies (‘vacuome’) undergo an irregular distribution and are cast out in the slough. The problem of distribution and localization in the sperm-cell formation are discussed with reference to the principle of genetic continuity in the germ cell.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Accounts of cortical adrenal development in urodeles are few in number and mostly incomplete from the point of view of development. Hence, an investigation was initiated to fill in existing gaps and present a complete developmental history of the glands in one of the urodeles.The primary anlagen of the cortical adrenal (interrenal) were seen first in the 8.8-mm. embryo as paired or unpaired cell groups in the interrenal area of the 'tween zone lying either in contact with or just beneath the coelomic epithelium. It was not possible to determine definitely whether they originate from the coelomic mesothelium or from the subjacent mesenchyme. Subsequent primordia are formed continuously throughout the period of larval development in an antero-posterior time sequence. Almost immediately they become associated with the postcaval system and the relationship thus established persists throughout life. There is no evidence of a budding process as described by Albrand ('08).During development there is a progressive increase in the size and number of cortical masses, an increase in the total area occupied by them, and a posterior shifting of the tissue as a whole as determined by its position in relation to the spinal ganglia. The definitive distribution is attained at the time of metamorphosis. The tissue occurs abundantly along the postcava, but strands along the median edge of the mesonephroi, as in some urodeles, are only sparingly developed.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 1-26 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Panniculus carnosus is well developed in the five Didelphids studied. It is described in three parts: pars dorsalis, pars thoracoabdominalis and pars pudenda, in Marmosa, Didelphis, Metachirops, Metachirus and Chironectes, and in Orolestes, a caenolestid marsupial. Pars dorsalis is well developed in all five genera, but not so well developed as in Orolestes; pars thoracoabdominalis is present in all five Didelphids, but not in Orolestes; and the degree of development of pars pudenda is correlated with the development of the pouch, being absent in Orolestes, weak in Marmosa and strong in both males and females of the other genera. In Chironectes, in which genus the male develops a pouch, pars pudenda is strikingly developed. The ‘sphincter marsupii’ of other writers is considered to be a portion of pars pudenda.In early development an epidermal ridge arises surrounding part of the mammary area. In Marmosa these ridges move laterally and posteriorly before the expanding mammary area. In Didelphis, Metachirops, Metachirus and Chironectes the ridges form the lips of the pouch. The pouch is formed when the ridges remain stationary and the expanding mammary area throws the skin into a double-walled fold.
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 127-148 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Gelgi bodies in Meretrix casta being visible in fresh eggs, an attempt was made to elucidate the nature of the contents of neutral red vacuoles. These are neo-formations which arise on treatment with neutral red Ringer. As recent researches have shown that neutral red forms compounds with enzymes, it is suggested that the new vacuoles in Meretrix are visible products of the attempt of the Golgi apparatus to eliminate neutral red which is a foreign substance to the egg. The function of Golgi bodies in the control of cell metabolism by production of intra-cellular enzymes is discussed.
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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 175-221 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The reproductive organs of Bruchus quadrimaculatus Fabr., and B. (Callosobruchus) chinensis L., including histology are described in detail. The role of the different parts of the male and female copulatory apparatus is discussed and the physical composition and function of the secretions of the accessory glands are indicated. The specific differences in the structure of the genitalia of the two species are shown.
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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: Using the percentage of mitotic figures in the cells as an index, a study was made of the distribution of cell multiplication in the development of the chick embryo. Counts were made of all regions in embryos ranging from the embryonic shield stage to sixteen somites, and of the neural and sensory epithelia and axial mesoderm of older embryos. Figures are presented which are believed to establish the sufficiency of mitotic division in producing the cell increases in the early embryo. In the developing primitive streak, areas of superior division rate were found in the presumptive medullary plate ectoderm at the sides of the streak. The node and the primitive plate tend to exhibit lower rates than the axis of the streak. The posterior nerve cells multiply more rapidly than the average of the neural tube, and areas of activity in the mesoderm tend to be located near the posterior end. An antero-posterior gradient of the index is indicated in the anterior neural tube, meeting a transient postero-anterior gradient of the hinder cord in the yolk-sac region. A lower rate of division in the floor than in the sides of the neural ectoderm may be implicated in the inrolling of the medullary plate and in the ventral ourvature of older embryos. All indices drop progressively with advancing age and differentiation.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937) 
    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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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 453-471 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the fifty generations of reared Nemeritis, males have been totally lacking. Oogenesis is atypical in (1) the occurrence of a pronounced and lengthy prochromosome stage, (2) the partial fusion of the eleven tetrads at early first anaphase, (3) following first anaphase, a return of all dyads from both poles to form a common second metaphase plate consisting of twenty-two separate dyads, (4) a second division which forms a single polar nucleus and an egg nucleus, each with twenty-two chromosomes, (5) the parthenogenetic development of the egg nucleus with twenty-two chromosomes. Oviposition, which occurs at first anaphase, is followed by a pronounced swelling of the egg through osmosis. Oogonia, follicle cells, cleavage nuclei and somatic cells in later embryogeny all show twenty-two metaphase chromosomes, while pupai tissue shows also tetraploid and octoploid complexes.
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  • 12
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 525-561 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Descriptions and figures of the subordinate sex-organs are given for thirty species taken at random throughout the entire family.It is found: that the higher genera have organs not present in the lower; that they have a storage sac for mineral particles to be added to the secreted capsules within which the eggs will develop; that the anus is more or less fused to the mouth of the oviduct to allow of easy passage of the above materials from anus to oviduct; that spermatophores grade from simple elongated tubes of the lower to stout double tubes with various forms, with spicules, or with spirals, in the higher forms; that the sacs for holding the spermatophores may be simple, when the spermatophores are cast out after discharge, but are more evolved when spermatophores are to be permanently retained and digested; that while lower forms have no sex organs upon the head, peculiar organs occur in the higher genera, in one or both sexes.These organs have value as aids in classification of genera within the family Neritidae. The very marked coordination among these organs may be better understood when further observation reveals how they are used in sperm transfer.
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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 581-611 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anatomically, the structure of the pancreas in four species of anura studied, is very similar during various stages of development. The gland is greatly reduced in size during both artificially induced and natural metamorphosis. When metamorphosis is artificially induced, the regression of the pancreas occurs somewhat earlier and is a little more rapid than in the case of natural metamorphosis, but the condition exhibited at the end of the phenomenon is similar in each case. Correlated with the anatomical regression during metamorphosis, many of the acinous cells, small collecting ducts and sinusoidal capillaries, undergo degeneration. This histolysis occurs somewhat earlier in animals that undergo artificially induced metamorphosis, but regeneration occurs about the same time in both metamorphic types. Most of the degenerated elements are autolyzed in situ; some are sloughed into sinusoidal capillaries; while a small number are eliminated through pancreatic ducts. It is doubtful whether these elements are ingested by phagocytes. The pancreas, in certain cases during later stages of metamorphosis, appears to take on a temporary hematopoietic function leading to the differentiation of red blood cells. Zymogen granules, lipoid granules, and X-granules are demonstrated in the anuran pancreas. X-granules, found in the larvae, are indeterminate in nature and are quite probably remnants of vitelline material found in the early embryo.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 361-377 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The adrenal-autonomic systems were studied in embryonic and juvenile alligators. In the class Reptilia virtually no previous work has been done on the adrenal-autonomic systems.The adrenals are definite bodies, distinct from the kidney. In young forms they are in close proximity to the gonads and in both the embryonic and young forms the adrenals lie against the wall of the inferior vena cava.Cortical cells predominate. In embryonic forms the medullary tissue is not dispersed as in older forms. The medullary tissue lies in close proximity to the blood sinuses or may completely surround them.The arterial supply is scanty there being only a few small arteries to the adrenal while the blood supply from the inferior vena cava is profuse.The innervation is segmental in nature with four or five consecutive sympathetic ganglia giving off sympathetic nerves to the adrenal. Parasympathetic innervation was not observed in the forms studied. The innervation suggests a transition from lower forms with their segmental diffuse medullary material to the higher forms that display concentration of nerve supply and adrenal tissue.
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  • 15
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    Journal of Morphology 60 (1937), S. 325-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Comparative data give the basis for reinterpreting alleged chromidia, mitochondria and Golgi material described for certain rhizopods.Three distinct groups of granules can be demonstrated in both Amoeba and Arcella by techniques ordinarily employed for revealing chromatin elements of a cell, mitochondria or Golgi material. With respect to physico-chemical properties the granules appear identical with certain forms of bacteria in the culture media. They are not destroyed by alcohol, ether, or Altmann's fluid containing 5% acetic acid.These granules are apparently bacteria; two groups representing permanent cytoplasmic entities either as symbionts or commensals, the third possibly temporary invaders.None of the cytoplasmic inclusions of these rhizopods have given the characteristic mitochondrial reaction when treated with Janus green. Spherules and granules, or alleged Golgi material, in Amoeba blackened with osmic acid can be revealed by techniques ordinarily employed for demonstrating the chromatin elements of a cell. Similar spherules and granules occur in the gelatinous material of the culture media, free or in bodies similar to those sometimes found in food vacuoles.In Arcella, neutral-red-stainable and osmiophilic bodies, apparently identical with granules or small globules found individually distributed in the cytoplasm, can be observed both in food bodies in food vacuoles and in similar food organisms in the medium. Those occurring in the cytoplasm may represent indigestible material.
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  • 16
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 445-458 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A description is given of the gross anatomy of the tracheal system of the larva of Drosophila melanogaster. Comparisons of findings are made with those of Lowne for Calliphora, Wahl for Eristalis, Simms for Hylemyia, Dufour for Sarcophaga, Wandolleck for Platycephala, Trägårdh for Ephydra, and De Meijere for Lonchoptera.
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  • 17
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    Journal of Morphology 60 (1937), S. 489-519 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Plethodon cinereus is favorable for a study of the history of the germ line. The germ cells are large, while the gonads are small and show an almost diagrammatic structure. Germ cell degeneration is not extensive during ontogeny. As long as all the germ cells contain yolk during development, these cells are derived solely from germ cells. In Plethodon, yolk lasts in all germ celis through sex differentiation. A comparison of the number of mitoses necessary for the primordial germ cells to produce the numbers of germ cells in gonads where every germ cell contains yolk, with the mitoses necessary for the primordial cells to produce the adult complements of germ cells, shows that at least 72% of the increase of germ cells can be followed by yolk. A cytological study from the embryo through the adult sexual cycle gave no evidence that somiatic cells ever transform into germ cells. Mitoses are abundant in the testes of salamanders starved 4 months. This fact together with a statistical study on the adult male sexual cycle indicates that the germ cells present in the testis do not need to be augmented by transformed somatic cells. It is concluded that in Plethodon germ cells alone give rise to germ cells, and that the germ line is continuous.
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  • 18
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cytological study of the complete life cycle of Nyctotherus cordiformis (Ehr.) Stein, a heterotrichous ciliate from the large intestine of tadpole and adult Hyla versicolor hosts is presented. In division a partial dedifferentiation of parental ingestatory structures occurs, then redifferentiation, to be retained by the anterior daughter. For the posterior daughter, the ingestatory apparatus arises de novo. In conjugation, two ciliates fuse along their peristomes. The macronucles undergoes complete fragmentation while the micronucleus divides three times. The first pregamic division results in two micronuclear products; the second division, four micronuclear products, three of which degenerate. The remaining product enters into the third pregamic division to produce the two functional, migratory and stationary, pronuclei. Interchange of migratory pronuclei follows at the fused anterior ends of the conjugants to form the amphinucleus which divides once to produce the micronucleus and the macronuclear anlage. Development and behavior of the unusual macronuclear anlage (‘spireme-ball’ of Stein and Schneider) is described for the first time. At the end of the conjugation process, ingestatory structures of each conjugant completely dedifferentiate while a complete new set arises de novo posterior to the old ones. In this case, conjugation occurs only in tadpoles which are metamorphosing into frogs. Conjugation here is interpreted as an effort made by the ciliates to overcome a physiological crisis during the drastic host transformation changes.
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  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The types of processes encountered in the various species investigated are described. There is included the topography and structure before birth of the gonads, mesonephric ducts, urinary sinus and gut. Following birth, there are but slight changes in the topography of these organs. The most important structural change involves a complete ectodermal reconstitution of the end of the gut to form a true rectum. The vascular supply to the processes in the different species is similar and varies only in the minute details. The arterial supply is furnished by an extension of a single mesenteric artery along the gut. The number of arteries and their position at the gut opening depends on the number and position of the processes at that point. Two venous channels drain the processes; one is somatic and drains into the caudal vein, the other is visceral and empties into the hepatic portal through the subintestinal vein. The former drains the posterior process, the latter, the anterior processes. This basic pattern is constant in all species investigated. A description of the rich capillary plexus on the surface of the processes is included. With the resorption of the processes after birth, vessels that supply them become variously modified. The vein to the anterior processes and the single artery are discontinued. The vein that drains the posterior processes either disappears or is retained in part, undergoing secondary connections.
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  • 20
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    Journal of Morphology 61 (1937) 
    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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    Journal of Morphology 61 (1937), S. 223-255 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the spermatogonia of all the genera studied, there are nineteen rod-shaped telomitic chromosomes, which differ considerably regarding their actual sizes in the different genera. However, an analysis of the measurements of second spermatocyte chromosomes shows that as regards proportional sizes and in seriation there is some degree of uniformity within the sub-family. In Aularches, Atractomorpha, Chrotogonus, Colemania and Pyrgomorpha, the members of the smallest pair of autosomes appear as roundish or oval bodies and are comparable in shape, relative size and behavior with the ‘small’ dot-like chromosomes of the general Acrididae, while in Orthacris and Zarytes they are not so and merge into the general series. The sex chromosome is the largest one in the complexes, or the second largest as in Poecilocerus. The usual forms of tetrads occur in the spermatocytes. It is found that the number of ring tetrads in any genus depends upon the length of its chromosomes; in genera with longer chromosomes there are more of them than in genera with shorter ones. While no final explanation has been offered regarding the chromosome relationship between this sub-family and the other Acrididae, some points arising out of the present study have been briefly discussed, and it is shown that a simple process of elimination of two pairs is not sufficient to explain the smaller chromosome number in Pyrgomorphinae.
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  • 22
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    Journal of Morphology 61 (1937), S. 385-397 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Concomitant with the appearance of the early secretion granules the nucleus enlarges slightly, the basichromatin is reduced and discrete acidophilic granules appear within the nuclei. Some nuclei become vacuolated and in others the basichromatin is practically reduced to a thin shell reinforced with occasional chromatic strands. Such nuclei are filled with acidophilic granules.In many instances the portion of the nucleus adjacent to the secretion is greatly modified, the basichromatin is reduced and presents an alveolar pattern with the alveoli filled with acidophilic material and elongated at right angles to the nuclear membrane. This appearance suggests that material is passing from the nucleus into the cytoplasm but no cytological evidence of such a passage was obtained.During the storage phase giant nuclei are present. They appear to be the result of a simple hypertrophy but in a few instances it appeared that multiplication by direct division, followed by coalescence might be a contributory factor to their formation.Following thyroidectomy or hypophysectomy the production of secretion was retarded but no profound regression was observed. After treatment with implants or injections of anterior pituitary a mild stimulation was observed.The evidence for nuclear participation in the formation of secretion is not conclusive but many of the changes which occur strongly suggest such an activity.
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  • 23
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The silver chromate method used by Cajal, Fusari, and others supporters of the ‘network’ theory, fixes the contraction bands and (M) membranes in contracted muscle and the (Z) membranes and borders of the (Q) discs in relaxed fibers. The same structures are preserved by fixation in gold chloride. Kolatchev, and Bouin solutions. Muscle tissue subjected, prior to fixation, to fat extractives: ether, chloroform, etc., and subsequently fixed by these methods has an appearance similar to control preparations. The Cajal-Fusari ‘network’ is therefore considered to result from an impregnation of the membranes and bands; the various types of ‘nets’ described by these observers being due to fixation of fibers in different stages of contraction.The true Golgi substance of striated muscle consists of osmiophilic bodies located in the sarcoplasm in proximity to the nuclei. Cone, saucer, or crescent-shaped osmiophilic bodies occur at the poles, and granules, rods or curved rods of similar staining material along the sides of the nuclei. The disposition of these structures varies from nucleus to nucleus. Heart muscle possesses a relatively larger amount of the substance than does skeletal muscle.
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  • 24
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    Journal of Morphology 61 (1937), S. 495-523 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The embryos of twenty-one species of the family Goodeidae have extensive rectal processes (trophotaeniae) which serve as absorptive organs, by means of which the embryos while they are retained in the ovarian cavity absorb substances dissolved in the ovarian fluid. Embryos of three species have not been available for study. No trophotaeniae are present in one species Ataeniobius toweri. There are three general types of trophotaeniae, rosette, sheathed and unsheathed. The structure of the trophotaeniae is sufficiently constant in each species to be used in species determination.
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  • 25
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    Journal of Morphology 167 (1981), S. 35-42 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vasculogenesis of the bursa cloacalis (bursa of Fabricius) was examined in 10- to 21-day chick embryos and in chicks during the first 5 days post-hatching. The entire circulatory system was injected with India ink, and the bursae were then removed and either cleared for examination in toto or sectioned serially. The bursa was supplied by three pairs of extrinsic blood vessels. At 10 and 11 days of incubation, most intrinsic vessels were arranged in a superficial, hexagonal network. In regions of developing plicae, the hexagonal plexus extended into the core of each plica, forming middle plical vessels. The latter were interconnected across interplical areas by cross-connecting vessels. The middle plical vessels gave rise to small capillary offshoots, which soon increased in complexity, forming delicate loops. Branches extended from these loops through the subepithelial lamina propria to incipient epithelial buds by 12 days of incubation. All epithelial buds were supplied by at least one such branch, and similar branches extended to the basal aspect of the epithelium in areas where epithelial buds had not yet formed. This observation is consistent with the hypothesis that blood vessels induce formation of epithelial buds. At about 15 days of incubation, the cortex and medulla of each developing lymphatic follicle were defined clearly, and an intricate, web-like, capillary network coursed throughout the follicular cortex. The medulla appeared to be devoid of capillaries. The diameters of all intrinsic and extrinsic bursal blood vessels gradually increased throughout development. During post-hatching stages, the diameters of the extrinsic vessels continued to increase, whereas those of the intrinsic vessels were markedly decreased from late pre-hatching stages.
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  • 26
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    Journal of Morphology 167 (1981), S. 103-108 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The use of hormone replacement to support limb regeneration in hypophysectomized newts has been the subject of many investigations. Growth hormone, as well as prolactin (PL) in combination with exogenously supplied thyroxine, have all been shown to he effective. However, the bovine growth hormone used to support limb regeneration was contaminated by prolactin and thyroidstimulating hormone (TSH). The present investigation evaluates the significance of (1) prolactin contamination and (2) endogenous thyroxine synthesis resulting from TSH contamination on limb regeneration in hypophysectomized newts. The effect of supplying exogenous thyroxine was also evaluated. Our studies showed that when hypophysectomized newts were injected with contamination levels of PL and TSH, regeneration occurred, suggesting that the newt's thyroid synthesized sufficient thyroxine to support a prolactin-thyroxine synergism. The endogenous thyroxine was synthesized by thyroid glands that were indistinguishable from those of saline-injected, hypophysectomized controls.
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  • 27
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    Journal of Morphology 167 (1981), S. 109-118 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β-gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot-pad, shows a pattern of histogenesis directly comparable to that of β-glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis.
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  • 28
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    Journal of Morphology 167 (1981), S. 167-184 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: There are four major tooth attachment modes in actinopterygians. Type 1 mode is characterized by complete ankylosis of the tooth to the attachment bone; it is the primitive attachment mode for actinopterygians. In Type 2 mode there is a ring of collagen between the tooth base and the bone. In Type 3 mode mineralization extends near or to the bone at the anterior tooth border, and there is a relatively large collagen area on the posterior surface of the tooth; Type 3 teeth are hinged with an anterior axis of rotation. Type 4 teeth also have a relatively large posterior collagen area, but there is no collagenous connection between the anterior basal tooth border and the attachment bone; Type 4 teeth are hinged, with a posterior axis of rotation. Types 2, 3, and 4 attachment modes appear to result from retardation of mineralization and resemble, with some modifications, ontogenetic stages in the development of Type 1 mode; they are considered to be paedomorphic features. Attachment modes 2, 3, and 4 are each associated with a major evolutionary lineage within the Teleostei. The degree to which paedomorphosis has been a factor in teleostean evolution is discussed.
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  • 29
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Bolitoglossa occidentalis, a lowland salamander of Mexico and Guatemala, has a highly derived morphology. The features that are derived with respect to the condition in generalized members of the genus include the following: (1) small body size; (2) short tail; (3) fully webbed hands and feet; (4) reduction and loss of certain phalangeal elements; (5) fusion of carpals and tarsals; (6) absence of prefrontal bones; and (7) reduced skull ossification. The ontogeny of this species was analyzed quantitatively and compared with the patterns of growth and differentiation encountered in two morphologically generalized members of the genus, B. rostrata and B. subpalmata. Most of the derived features can be explained by invoking a single heterochronic process: truncation of development at a small size (most likely the product of early maturation). Therefore, B. occidentalis is a paedomorphic species whose morphology has been attained through the process of progenesis. This result supports Alberch's ('80a) prediction, based on functional analysis, that the principle adaptation to arboreality in B. occidentalis is small size; other derived morphological features are associated with the organism's truncated development and may have no adaptive significance. However, patterns of dissociation are found within this overall progenetic process. Some of these include the following: (1) accelerated growth rates of the metatarsals and first phalanges, and retarded growth rates of the second and third phalangeal elements; (2) dissociation between rates of ossification of the skull and the autopodial elements; and (3) dissociation between the timing of termination of the process of shape change during the ontogeny of the foot (the product of differential growth between digital and interdigital areas) and termination of growth in overall foot size (foot surface area). This later result illustrates the independence of morphogenetic phenomena (shape change) from processes of growth (size increase).
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  • 30
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    Notes: A table of development (25 stages) for the period of incubation in the pouch was constructed for Gastrotheca riobambae; it can be used to stage embryos of other egg-brooding hylids. Analysis of embryonic weights during incubation shows that the mother does not contribute nutrients, but gases and other factors are probably exchanged between mother and embryos.According to species, incubation on the back of the mother is carried to the froglet or to the tadpole stages. Development in these hylids is characterized by specialized gills, the bell gills derived from the branchial arches. In some species, the bell gills derive from the first branchial arch and cover less than 50% of the embryo, while in others, the bell gills come from both branchial arches I and II and cover from less than 50% to 100% of the embryo. The most complex bell gills derive from the fusion of the two branchial arches.The majority of egg-brooding hylids live in tropical forests and carry development to the froglet stage. Tadpoles are produced by species of Flectonotus, Fritziana, and Gastrotheca. Tadpole-producing species of Gastrotheca have the most complex reproductive adaptations among egg-brooding hylids Acceleration and retardation in development seem to have played important roles in the evolution of these frogs. The evolutionary trend has been toward direct development, i.e., disappearance of the free-living larval stages through maternal incubation, and later to a recovery of the free-living tadpole stages in species of Gastrotheca with the most complex reproductive adaptations.
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    Journal of Morphology 167 (1981), S. 313-331 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ectodermal eyes, 45-55 μm in diameter, of the cnidarian hydrozoan Cladonema radiatum Dujardin possess a lens approximately 15 μm in diameter enveloped by an eyecup (retina). An overlying layer of intensely vacuolated distal process of the adjoining epithelial cells forms a transparent cornea. The eyecup is composed of three cell types: basal cells, melanin-containing pigment cells, and photoreceptor cells. The last two cell types occur in the ratio of approximately 2:1. Histogenesis of the eye both during ontogeny and regeneration is described from light and electron microscopic investigations. During ontogeny the cell types forming the retina are derived from a compact group of morphologically undifferentiated cells, but during regeneration a primordium is formed by regeneration cells. In both cases the lens is built from distal nonnucleated cytoplasmic portions pinched off from the pigment cells. The cornea is formed by distal lamellar processes of the ocellus adjoining the epithelial cells. Through EM-histochemical methods (silver impregnation and DOPA-oxidase reaction) the pigment of the chromatophores of the retina was identified as melanin.
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    Journal of Morphology 168 (1981), S. 247-247 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 33
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    Journal of Morphology 168 (1981) 
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  • 34
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    Journal of Morphology 168 (1981), S. 189-227 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The neural organization of the olfactory system in the desert iguana, Dipsosaurus dorsalis, has been investigated by using the Fink-Heimer technique to trace the efferents of the main and accessory olfactory bulbs, and Golgi preparations to determine the spatial relations between olfactory afferents and neurons in the primary olfactory centers.The accessory olfactory bulb projects to the ipsilateral nucleus sphericus via the accessory olfactory tract. The main olfactory bulb projects to the ipsilateral telen-cephalon via four tracts. The medial olfactory tract projects to the rostral continuation of medial cortex and to the septum. The intermediate olfactory tract projects to the olfactory tubercle and retrobulbar formation. The lateral olfactory tract projects to the rostral part of lateral cortex. The intermediate and lateral olfactory tracts also merge caudally to form the stria medullaris, which crosses the midline in the habenular commissure and distributes fibers to the contralateral hemisphere via two tracts. The lateral corticohabenular tract terminates in the contralateral lateral cortex. The anterior olfactohabenular tract terminates in the contralateral olfactory tubercle, retrobulbar formation and septum.The relation of olfactory afferents to neurons in the medial cortex, lateral cortex, nucleus sphericus, and septum corresponds to a pattern of organization that is typical of many olfactorecipient structures. Such structures are trilaminar, with neurons whose somata are situated in the intermediate layer (layer 2) sending spine-laden dendrites into an outer, molecular layer (layer 1). Olfactory afferents intersect the distal segments of these dendrites. By contrast, other olfactorecipient structures in Dipsoaurus deviate from the familiar pattern. Olfactory afferents intersect somata lying in layer 2 of the retrobulbar formation. Olfactory afferents include some fibers which course perpendicularly to the surface of the olfactory tubercle and extend deep to layer 2.
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    Journal of Morphology 168 (1981), S. 281-288 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microscopic examination of adipocytes isolated from adult rat epididymal adipose tissue revealed numerous small cells (〈 10 μm) morphologically similar to larger adipocytes. These small adipocytes appear identical to a new classification of adipose cells termed preadipocytes. Electron micrographs of these preadipocytes revealed examples of cells 〈 10 μm in diameter in various stages of maturation and lipid accumulation. The percent distribution pattern of these small adipocytes was not significantly altered by exercise although exercise shifted the distribution patterns of the larger cells (〉 30 μm) toward a smaller mean cell size. The quantitative significance of preadipocytes is not established but these preliminary observations indicate that adipocytes 〈 10 μm in diameter may account for a numerically greater proportion of the total adipocytes observed in collagenase isolated preparations than heretofore recognized, although their contribution to total adipose mass is probably negligible.
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  • 36
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    Notes: When a newt is hypophysectomized prior to or at the time of forelimb amputation a dermal barrier eventually forms between the apical cap of epithelium and the underlying mesenchymal tissues, and the typical regeneration response is transformed to a wound-healing morphology. When hypophysectomized newts are injected on continuous alternate days beginning either at the time of amputation or following a fifteen-day delay, with either growth hormone (GH) or prolactin in combination with thyroxine (PLT4), normal regeneration occurs. Our experiment was designed to examine critically the early changes occurring in apical connective tissue that had been allowed to form as a consequence of hypophysectomy prior to forelimb amputation. Adult newts were hypophysectomized and five days later both forelimbs were amputated distal to the elbow. Following a delay of eight days, to permit the formation of connective tissue beneath the apical epithelium, they were injected intraperitoneally on successive alternate days with GH or with PL in combination with T4 in the aquarium water. The apical connective tissue of the limb stumps underwent a progressive erosion and became discontinuous by day 4. The limb morphology of hypophysectomized newts receiving ACTH or PL or maintained in thyroxine was virtually identical to sham-injected hypophysectomized controls. It appears that an initial effect of GH or PLT4 therapy is to establish the epithelial-mesenchymal interface that previously has been suggested to be a requisite for the regenerative event.
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  • 37
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    Notes: The external features of the embryo and the first instar larva of Pedetontus unimaculatus are described. Blastokinesis of P. unimaculatus is very similar to that of Petrobius brevistylis (Larink, '69), but differs from that of Machilis alternata (Heymons and Heymons, '05). The superficial structures of three pairs of protocerebral lobes are present. The terga of the mandibular, maxillary, and labial segments take part in the formation of the head capsule. In the maxilla and labium, the palpi are homologous with the telopodites of the legs; the other parts proximal to the palpi are homologous with the coxopodites. No sternal element contributes to the postmentum. Both glossa and paraglossa consist of two lobes. The pleuropodium, stylus and ventral sac are derived from distal parts of appendage anlagen. The pleuropodium of the first abdominal segment is homologous with the styli of the successive abdominal segments; the ventral sacs of succeeding segments are serially homologous. The basal parts of appendage anlagen cover each sternum in the first to ninth abdominal segments to form coxites, which are therefore appendicular in origin. The basal part of the cercus also covers the ventral and lateral surfaces of the eleventh abdominal segment.
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  • 38
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    Notes: The micropterygid moth Neomicropteryx nipponensis belongs to the most primitive suborder Zeugloptera of the Lepidoptera. During embryogenesis the small circular germ disk formed on the ventral egg surface invaginates deeply into the yolk. It finally separates from the egg periphery or rudimentary serosa, and becomes a sac-shaped germ rudiment. Its anterior part later develops into the germ band, while its posterior part is the future amnion. Just before revolution of the embryo, the embryo assumes a completely superficial position beneath the yolk. Neither amnion nor serosa rupture during revolution; by completion of dorsal closure they have been incorporated into the yolk to form the secondary dorsal organ.The formation of the germ rudiment and embryonic membranes in N. nipponensis resembles those of swift moths, Endoclyta (suborder Monotrysia) and of the caddisflies, Stenopsyche (Trichoptera), but differs from those of ditrysian Lepidoptera. The secondary dorsal organ has never been found in any other lepidopteran embryos; however, it is formed in N. nipponensis and in the Trichoptera. The results of the present study strongly support the general phylogenetic views that the Zeugloptera have a close affinity to the Trichoptera.
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  • 39
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    Journal of Morphology 169 (1981) 
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  • 40
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    Journal of Morphology 169 (1981), S. 29-47 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning and transmission electron microscopic observations were made on the rattlesnake lung, which has the form of a cigar-shaped bag enclosing a large axial air chamber. The lungs were fixed by tracheal instillation of fixative to preserve the structural features of inflated lungs. An open tracheal groove along the ventral aspect of the lung is the only structural “airway” present. The wall of the lung has two histologically distinct regions: anteriorly, a respiratory portion, where up to three generations of septa subdivide the wall into cup-shaped gas-exchange chambers, termed faveoli; and posteriorly, a simple, thin-walled saccular portion. The epithelium lining the internal surface of the lung is composed of several cell types: (1) ciliated cells; (2) type I pneumonocytes; (3) type II pneumonocytes, secretory cells characterized by the presence of lamellar bodies; and (4) serous epithelial cells, secretory cells characterized by the presence of homogeneous, densely staining secretory granules. However, the distinctiveness of the secretory cell types in the snake lung is blurred because intermediate-appearing cells have both the lamellar body and homogenous type of secretory granule. The nonepithelial components of the pulmonary wall and septa consist of blood vessels and lymphatics, smooth muscle cells and fibroblasts, embedded in a matrix of extracellular connective tissue fibers. Tubular myelin figures were observed in the faveolar lining layer.
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  • 41
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    Journal of Morphology 169 (1981), S. 91-111 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Autoradiographic, HRP, and Fink-Heimer techniques define olfactory bulb efferents in the channel catfish. The olfactory bulb projects bilaterally to eight targets in the area ventralis telencephali including the preoptic area, five targets in area dorsalis telencephali, and the posterior tuber of the diencephalon. There is additional input to the peripheral margin of the internal cell layer of the contralateral olfactory bulb. Fibers cross in rostral (nervus terminalis and commissure of Goldstein) and caudal components of the anterior commissure and the habenular commissure. HRP techniques reveal the origin of bulb efferents from the internal and mitral cell layers of the olfactory bulb. The olfactory tract is divided into five major components, each with a unique subset of ipsilateral and commissural pathways.
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    Journal of Morphology 169 (1981), S. 149-159 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anuran (Rana) and urodele (Ambystoma) amphibian eggs were subjected to prolonged unnatural orientations in relation to gravity. In some cases eggs were rotated 90°, while in other instances eggs were rotated 180° (complete inversion). Alterations in the pigmentation pattern, cleavage pattern, and site of involution were observed. Despite these unnatural orientations to gravity, the morphogenesis of axial structures was frequently normal. Reorganization of the egg cytoplasm apparently takes place after the unnatural orientation. Rather than being localized in a fixed position in the egg (e.g., the egg cortex), the determinants for the pattern of early embryogenesis are probably located in that portion of the cytoplasm (e.g., “internal” cytoplasm) that orients to gravity.
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  • 43
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    Journal of Morphology 169 (1981), S. 207-223 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoarchitecture and neuronal morphology of the torus semicircularis in the red-eared turtle, Chrysemys scripta elegans, were examined in Nissl-stained and Golgi-impregnated material. The torus semicircularis begins in the caudodorsal mesencephalon and extends rostrally and laterally to end ventrally to the tectal ventricle. The torus semicircularis consists of a central nucleus and a laminar nucleus, which is interposed between the central nucleus and the ventricle.The central nucleus can be divided into two regions, a small, large-celled area, located dorsally, and a larger area of small spherical (6-17 μm), large spherical (18-25 μm), triangular (15-27 μm) and fusiform (10-26 μm) neurons. The small spherical cells have two dendritic patterns: “radiate” and “single.” The radiate pattern has a dorsoventral orientation, several secondary branches and few dendritic spines. These cells are usually located in the center of the central nucleus. The single pattern is oriented mediolaterally. This cell type is most often observed at the periphery of the central nucleus. These neurons have few secondary branches and dendritic spines. The large spherical neurons display two dendritic orientations: dorsoventral and mediolateral. All dendritic trees have numerous secondary branches and few dendritic spines. The triangular neurons exhibit primary dendrites projecting from the corners of the somata and have few secondary branches and dendritic spines.The fusiform neurons have a majority of their dendrites oriented mediolaterally, few secondary branches and a small number of dendritic spines.The laminar nucleus consists of several layers and three cell types: ovoid (9-15 μm), triangular (20-40 μm), and fusiform (20-40 μm). All neurons have few secondary dendritic branches and few dendritic spines. The dendrites of many neurons course perpendicularly to the long axis of the brainstem and encapsulate the central nucleus. Some ovoid and fusiform neurons display dendrites that enter the central nucleus.
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    Journal of Morphology 170 (1981), S. 113-131 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the foregut muscles of five spider families (Theraphosidae, Agelenidae, Araneidae, Lycosidae, Salticidae) was described, and the individual fibre numbers and fibre cross diameters of the muscles were determined. The nomenclature of these muscles was reviewed and modified if necessary.Oxidative enzyme and myosin-ATPase histochemistry revealed eight dilatatory muscles of the foregut to consist of slow (type I) fibres, while fast fibres (type IIB), and intermediate fibres, were only to be found in the two other muscles of the foregut, and in the remaining prosomal muscles (type IIA fibres around the poison gland).The eight sucking muscles proper of the foregut also showed stronger activities of transmitter metabolizing enzymes [monoamine oxidase, glutamate dehydrogenase(NAD)], and comparatively distinct amounts of glycogen and lipids.
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    Journal of Morphology 169 (1981), S. 325-336 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reports observations on the innervation of gill filaments of the lamprey, Lampetra japonica. Nerve fibers run on each side of the afferent filament artery (AFA nerve) and in the connective tissue compartment along the efferent filament artery (EFA nerve). The AFA nerve supplies vasomotor fibers to the afferent filament artery and arteriovenous anastomoses and special visceral motor fibers to branchial muscle fibers (musculus compressor branchialis circularis). Nerve endings of the vasomotor fibers contain large, cored vesicles (60-180 nm in diameter) with a variable number of small, clear vesicles (30-70 μm in diameter), whereas those of the visceral motor fibers have many small, clear vesicles with few large, cored vesicles. The EFA nerve supplies vasomotor fibers to the efferent filament artery. Their endings, containing mixtures of predominantly large, cored vesicles and small, clear vesicles make close synaptic contacts with reticular cells. The latter in turn are connected with each other or with smooth muscle cells in the wall of the efferent filament artery by nexuses. No nerves are found in the axial plate between the afferent and efferent filament arteries nor in the secondary lamellae of individual gill filaments. No afferent nerve supply to the gill filament has been found.
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    Journal of Morphology 169 (1981), S. 351-355 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study, using the cobalt chloride technique, clarifies the origin of the giant axons in the cockroach, Periplaneta. Each giant axon in the ventral nerve cord arises from a single cell body located in the sixth abdominal ganglion. The position of the soma is always contralateral to the giant axon; it projects anteriorly. In six giant neurons, the axonic and dendritic branches are ipsilateral while the somata are contralateral. In two neurons, both the soma and the dendritic branches are ipsilateral while the axons are contralateral. The dendritic arborizations of the giant neurons form a dense and compact mass of neuropile in each half of the posterior and middorsal part of the ganglion where sensory fibers, primarily from the cercal nerves terminate. The relation of these findings to earlier electrophysiological studies is discussed.
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    Journal of Morphology 170 (1981) 
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  • 48
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    Journal of Morphology 168 (1981), S. 309-319 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Untreated adult newts do not undergo normal limb regeneration following hypohysectomy. A fibrocellular dermal barrier (cicatrix) atypically forms between the apical epithelium and the underlying mesenchymal tissues. Historically, continuous administration of growth hormone or of prolactin in combination with thyroxine restored regenerative capacity to these newts. In a previous investigation, we demonstrated that the initial effect of these two hormone treatments, when administered on alternate days to hypophysectomized newts beginning eight days post-amputation, was to facilitate the erosion of the fibrocellular barrier and establish the epithelial mesenchymal interface that is observed in a regenerating limb.The present investigation was designed to evaluate the necessity of continuous hormone therapy to maintain limb regeneration in hypophysectomized newts. One, two, or three injections of growth hormone or of prolactin in combination with thyroxine was administered on successive alternate days to hypophysectomized newts either immediately following limb amputation (ID) or beginning eight days post-amputation (DD). The ID and DD newts receiving one, two, or three injections of growth hormone showed evidence of regeneration to the digitiform stage by day 30 post-amputation, while those receiving prolactin and thyroxine underwent wound healing. While both hormone treatments initially promoted a dermis-free apical epithelium, only hypophysectomized newts that had received growth hormone were able to continue regenerating.We have, therefore, concluded that discontinuous growth hormone therapy is sufficient to initiate and maintain the conducive environment for limb regeneration to advanced stages in the hypophysectomized newt. While initiating this process, prolactin and thyroxine therapy on a discontinuous regime does not maintain regeneration. The direct and indirect role of growth hormone in supporting limb regeneration in normal and hypophysectomized newts is discussed.
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  • 49
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    Journal of Morphology 170 (1981) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 50
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    Journal of Morphology 169 (1981), S. 71-90 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoarchitectonics of the telencephalon of the channel catfish, Ictalurus punctatus, are described as a basis for experimental analysis of telencephalic afferents and efferents. The olfactory bulb comprises: (1) an outer layer of olfactory nerve fibers, (2) a glomerular layer, (3) an external cell layer, (4) an inner fiber layer, and (5) an internal cell layer. The telencephalic hemispheres comprise the areas ventralis and dorsalis telencephali. The area ventralis consists of: (1) a precommissural, periventricular zone including nucleus 'nother (Vn), the ventral nucleus (Vv), and the dorsal nucleus (Vd); (2) a precommissural, migrated zone of central (Vc) and lateral (VI) nuclei; (3) a supracommissural nucleus (Vs); (4) a caudal commissural zone of postcommissural (Vp) and intermediate (Vi) nuclei; and (5) a preoptic area (PP). The area dorsalis comprises: (1) medial (DM), (2) dorsal (Dd), (3) lateral [DL, containing dorsal (DLd), ventral (DLv), and posterior (DLp) regions], (4) posterior (DP), and (5) central (DC-1, -2, -3) areas. Nucleus taeniae (NT) is transitional between areas dorsalis and ventralis.
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  • 51
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    Journal of Morphology 169 (1981), S. 61-70 
    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 newly hatched larva of Carcinonemertes epialti Coe has been examined by light and electron microscopy. The newly hatched larva is covered with cilia and measures about 110 μm in length. Four types of epidermal cells are recognizable: (1) Multiciliated cells, (2) vacuolated cells, (3) mucous cells, and (4) “knob cells”. The knob cells protrude from the posterior end of the larva and contain granules and bundles of microfilaments. The gut is incomplete and is located ventral to the bipartite proboscis. A bilobed brain and two subepidermal ocelli are found in the anterior end of the larva. The anterior and posterior cirri are composed of long, tightly appressed cilia that arise from an invagination of the epidermis at each end of the larva. The anterior cirrus is surrounded by two types of glandular cells. It is proposed that the knob cells have a role in larval attachment, combining the functions of the adhesive cells and anchor cells described in the duo-gland system of turbellarians. The cirri are believed to be larval sensory structures that function in substrate selection. Histological and ultrastructural observations suggest that the larvae of Carcinonemertes are relatively long lived and develop into juveniles without a drastic metamorphosis.
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  • 52
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    Journal of Morphology 169 (1981), S. 141-148 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glycoproteins are present in the web of the orb-weaving spiders Argiope trifasciata and Argiope aurantia. Periodic acid-Schriff reactive glyco-proteins are confined in large part, to the sticky spiral and sticky spiral-radial junctions. Glycoproteins containing amino sugars appear associated with all fibers, especially the radial fibers. Enzymes may be used to remove glycoproteins selectively from the sticky spiral and stabilimentum.
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  • 53
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    Journal of Morphology 169 (1981), S. 191-206 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pineal organ of Ensatina eschscholtzi, a terrestrial and secretive species of salamander of the family Plethodontidae, is a photoreceptive structure lying on the dorsal surface of the diencephalon. The pineal is flattened with a broad lumen and consists of three cell types: photoreceptors, supportive cells, and neurons. Pineal photoreceptors are typical vertebrate photoreceptors and possess outer segment formations which, however, are frequently contorted and disorganized. Sloughing of apical portions of outer segments and vesiculation along the lateral edges of outer segment membrane disks are consistently observed and presumed to represent mechanisms of outer segment membrane recycling. Photoreceptors have basal processes which synapse with neural dendrites. Synapses between photoreceptor basal processes are occasionally observed. All synapses are characterized by synaptic ribbon structures of variable number, size, and configuration. Dense-core vesicles are occasionally observed mingled with clear synaptic vesicles within photoreceptor basal processes. Supportive cells within the pineal function in phagocytosis and recycling of shed outer segment membrane material, and neurons are localized at the lateral margins of the organ. The latter send axons into the ipsilateral side of the dorsal diencephalon. The pineal organ of Ensatina shows marked variation in overall size (cell total), cell type proportions, absolute neuron number, and ratio of photoreceptor number to neuron number for individual pineals. None of these morphological parameters is correlated with body size, sex, or season, and it is assumed that such variability represents significant variation in photosensory capabilities. It is suggested that the pineal organ of Ensatina is a partially degenerate photoreceptive structure.
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  • 54
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    Journal of Morphology 169 (1981) 
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  • 55
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: In order to investigate quantitatively and objectively the influence of the normal microbial flora on the ultrastructure of the alveolar macrophage, three groups of mice were studied stereologically: germ-free (GF), conventionally reared under non sterile isolation conditions (IC), and conventionally reared in an open environment (OC). The alveolar macrophages of GF mice possess a smaller mitochondrial compartment, possibly with fewer organelles, than the macrophages of conventional mice. Other influences of the normal microflora on alveolar macrophage substructure are obscured by the effects of nonmicrobial stimuli such as droplets of lung surfactant.No previous comparison exists of alveolar and peritoneal macrophage ultrastructure. Lung macrophages are larger than the phagocytes of the peritoneum, but the difference in size is much less than is commonly believed. Alveolar macrophages are rounder than peritoneal macrophages, and exhibit much less rough endoplasmic reticulum (RER) as well as differences in mitochondrial morphometry. No difference in mitochondrial volume fraction exists between the two types of macrophage even though alveolar macrophages represent the extreme of aerobic adaptation in the mononuclear phagocyte system. Phagosomes occupy a significant fraction of cellular volume only in the alveolar macrophages. Moreover alveolar phagocytes contain fewer but larger lysosome-like granules than are found in peritoneal macrophages. The results represent the first objective, quantitative structural evidence confirming the common belief that alveolar macrophages experience greater physiological stimulation than peritoneal macrophages. The normal microflora accounts for only a small proportion of the differing degree of stimulation exerted on the two types of macrophage.
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  • 56
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this work, we have completed a study of the development of the ovoviviparous lizard Liolaemus tenuis tenuis. Ovoviviparity in this lizard is a condition in which eggs are retained within the reproductive duct for about 60 days. During this period the phases of segmentation, gastrulation, neurulation, presomitic, and somitic embryos transpire. During the months of December and January the eggs are laid, and at this time the embryos are comparable to stage 27 Liolaemus gravenhorsti lizard embryos, or to stage 29 Calotes versicolor lizard embryos. Differentiation of the facial region occurs between Days 12 and 42 after egg laying. Limbs develop rapidly between the 8th and 23rd days. By 53 days the appendicular skeleton is completely formed. After 36 days the mesonephros begins to degenerate, and its function is gradually taken over by the developing metanephros. Newborn lizards do not possess an egg caruncle. During the period up to hatching, there is a great increase of liquid within the egg, presumably amniotic fluid. Cracks develop in the leathery shell shortly before hatching and are, perhaps, the first sign of the onset of hatching. Increase of liquid in the egg during postlaying development accounts for its increase in weight and change in shape. Weight of the embryo at hatching does not exceed 32% of the total weight of the egg.
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  • 57
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    Journal of Morphology 170 (1981), S. 1-27 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The coronary arterial supply and associated structures have been examined and described for 29 species covering 11 reptilian families, with supplementary observations on other species. Variation in the origin, number, and configuration of coronary arterial vessels is mainly interfamilial and the same is true regarding the presence or absence of a gubernaculum cordis. It is suggested that the presence of a hitherto unrecognized intertruncal branch of the coronary artery has been responsible for much of the alleged intrafamilial variation reported in earlier literature. A general review of the cardiac blood supply and coronary arterial supply of other lower vertebrates is presented and used as a basis for interpreting phyletic and functional aspects of the reptilian conditions.
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  • 58
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    Notes: The enameloid and dentine of Squalus acanthius have been compared histochemically with those of Bos taurus. Squalus enameloid is much less reactive to a variety of stains or reagents than dentine or bovine immature enamel but it does have positive reactions with picromethyl blue, Mallory's and Van Gieson's stains, and Alcian blue. It stains faintly with Biebrich scarlet, indicating some anionic groups. Specific reactions for tyrosine, tryptophane, lysine, histidine, arginine, and cysteine are negative. Bos immature enamel is positive for cationic, anionic, and aromatic reactive groups by all test procedures, and dentine was positive for the anionic components. Bovine maturing enamel, however, is more similar in terms of lack of reactivity to Squalus enameloid but differed because the bovine enamel was moderately positive for tyrosine; tryptophane, and anionic groups and negative with Mallory's picromethyl blue and Van Gieson's stains. A fibrous transitional area between Squalus dentine and enameloid has staining reactions characteristic of both collagen and keratins.
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  • 59
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    Journal of Morphology 170 (1981), S. 181-194 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five concentrations of nitrogen mustard (methyl-bis-chlorethylamine) have been administrated to different stages of development of trout embryos (Salmo gairdneri), in order to study their effect on the formation of both pelvic fins soft tissue and skeleton. Sensitivity of epidermis and mesoderm toward this cytotoxic agent has been assessed histologically. Although both components are sensitive to nitrogen mustard, mesoderm is more sensitive than epidermis. These results are compared with the results of similar studies on tetrapod limb buds. The pelvic fin skeleton of some treated animals was doubly stained in toto for cartilage and bone by Alcian blue and alizarin, followed by clearing. Other specimens were processed for histological serial sections. Analysis included comparison of the following parameters: (1) dose of nitrogen mustard, (2) stage of fin bud development at the time of treatment, (3) importance of necrosis in the fin bud, and (4) abnormalities of the endoskeleton of the fin (pelvic girdle and radials) and of the dermal skeleton (lepidotrichia and actinotrichia) one month after the hatching of control animals. Results suggest (1) that material of endoskeleton and lepidotrichia are laid down simultaneously, and (2) that differentiation of actinotrichia is independent of differentiation in endoskeleton and lepidotrichia.
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  • 60
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    Journal of Morphology 61 (1937), S. 149-163 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spermatozoon of Palaemon lamarrei is like a cricket ball having a small hole at the top. The outer leather covering of the ball represents the nucleus and the internal stuffing the cytoplasmic vesicle, in the formation of which almost the whole of the cytoplasm of the spermatid along with its mitochondrial and Golgi material is sacrificed. The hole is very efficiently plugged with a ring-like centrosome, which gives off inward a large number of axial filaments radiating through the vesicle toward the nucleus and outward a long prominent spine ending into a fine point. The acrosome is conspicuous by its absence. It has been suggested that, as in Paratelphusa spinigera, the cytoplasmic vesicle forms the mechanism, which is responsible for the explosion of the sperm at the time of fertilization. It has also been suggested that the bizarre structure of the sperm is closely associated with the necessity of ensuring the safety of this explosive vesicle until the time of fertilization. The chromatoid bodies described by Fasten in the crayfish, Cambarus virilis, must be interpreted as the Golgi masses.
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  • 61
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    Journal of Morphology 61 (1937), 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: The method of micro-injection was used in the study of a large number of tubules. The limits of the several parts of the tubule were determined with a high degree of accuracy without sectioning; the error of the measurements was small. Of 137 tubules studied the measurements of forty-nine comprised the entire length from renal corpuscle to collecting duct or ureter.The proximal tubule was found to be about twice as long as the distal. While the longest proximal tubule was nearly six times the length of the shortest, the great majority of tubules fell within a much shorter range. There was little or no correlation between proximal tubule length and weight of the animal.The proximal tubule is larger in diameter than the distal tubule. Calculations indicate that the area of exposed cell surface in the proximal tubule is nearly four times as great as in the distal; however, compared to tubule volume, a relatively greater cell surface is exposed in the distal tubule.
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  • 62
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    Topics: Biology , Medicine
    Notes: A study is made of the development of ovarian ova in mature rabbit does before and during various stages of pregnancy and after the injection of thyroid and anterior-pituitary-like hormones. No appreciable ovogenesis during sexual maturity was found. Nine types of ovarian follicle are distinguished according to size and degree of development. Full ovum size is reached in pre-antral follicles, and is marked by the formation of a dictyate nucleus and slight reduction in nuclear size. Full follicle size is attained much later. The nature of follicle migration in the course of development is described. Ovum migration within the follicle is found to be a consequence of the nature of the egg's attachments to the follicular epithelium. The least atresia is found in young oocytes (10%), the larger follicles showing about 60% atretic at all stages of the reproductive cycle. The hormone preparations administered affect only the largest follicles and their contained ova.
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  • 63
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    Journal of Morphology 61 (1937), S. 309-319 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anlage of the swim bladder of the Atlantic salmon arises as a small mass of undifferentiated cells resting dorso-laterally on the posterior wall of the fore-gut. This mound of cells is proliferated from the narrow band of mesoderm which lies between the epithelium and the serosa of the alimentary canal. The concentration thus formed elongates slowly for 11 weeks. At the end of this time an evagination from the lumen of the right side of the oesophagus grows into it. This tube commences to elongate rapidly just previous to the time of hatching, and reaches the posterior end of the body cavity at approximately the time when the young salmon emerge from the gravel. Throughout the fresh water life of the fish this organ is a relatively large thin walled sac, lying dorsal to the body cavity. Microscopic examination reveals layers typical of those of the digestive tract.
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  • 64
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    Journal of Morphology 61 (1937), S. 485-494 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper presents an account of the morphology of the hypophysis and adjacent hypothalamic regions of young adult Amblystoma tigrinum. The description deals primarily with reconstructed models made from blotting paper; transverse and sagittal sections are also considered. A new term, hypophysis, pars subdistalis, is used to describe a discrete portion of the hypophysis embedded in the medial and ventral portion of the pars distalis. The other portions of the hypophysis also are described in detail.
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  • 65
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    Journal of Morphology 61 (1937), S. 563-579 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper correlates the various aspects of the author's previous work on embryonic columnar epithelia and deals especially with the mechanical factors that determine the form of an epithelium. The origin of the terminal bars, the various forms the terminal bars assume, and the significance of the terminal bar net in maintaining the epithelial structure are discussed. The paper also gives detailed consideration to the elongation of columnar cells after division. When this change in shape cannot be attributed to crowding from without, it is suggested that a thrusting action of elongating spindle fibers is the internal force responsible. In either case elongation is influenced by the development of the terminal web limiting the free surface. Further observations on this structure, first described by the author in 1935, are presented. The terminal web, which is generally present in columnar epithelia, is a specialized part of fixed cytoplasm, condensed, and lying in the plane of the terminal bars. It disappears in mitosis, but its reappearance as the new cell elongates limits the area of the free end of the cell. Hence, the terminal web plays an important part in determining the form of columnar cells.
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  • 66
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    Journal of Morphology 60 (1937) 
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    Journal of Morphology 60 (1937), S. 393-405 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The epididymis in the male bird consists of the rete testis, ductuli efferentia, and epididymal tubules. The rete testis is lined with cuboidal epithelium not resting on a basement membrane. When distended with sperm the epithelium appears squamous-like. The tubuli efferentia are lined for the most part with pseudostratied ciliated columnar epithelium resting on a basement membrane. The epithelium is thrown into permanent longitudinal ridges. The epididymal tubules are lined with ciliated columnar epithelium resting on a bastment membrane.The three types of genital ducts are intermingled to some extent, but maintain a definite sequence in their connection with one another. The rete testis drains into the tubuli efferentia, and the latter into the epididymal tubules. These drain into the vas deferens.
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  • 68
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    Journal of Morphology 60 (1937), S. 459-487 
    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 male sexual cycles of five species of Plethodontid salamanders indicated that annually occurring non-functional regions at the anterior and posterior ends of the testis are associated with the two types of germ cell degeneration: (1) extensive degeneration of secondary spermatogonia in the anterior region; (2) complete degeneration in the posterior region, beginning with the young spermatocytes, of all germ cells except the primary spermatogonia. The improbability of the posterior degenerations being caused by a suggested climatic action is discussed. The presence only in urodeles of a caudo-cephalic polarity of spermatogenesis over the length of the testis and of these degenerations seem more than a coincidence. The abortive spermatogenetic cycle of immature males shows a caudo-cephalic sequence and the stages of degeneration that are identical with the adult. Inanition experiments indicate that the formation of secondary spermatogonia and the ability to form sperm are not synonomous. It is suggested, therefore, that normally more of the testis is activated than can be brought to a successful spermatogenesis. Since spermatogenesis moves caudo-cephalically, the posterior end will be left outside the functional zone, and consequently the cells degenerate. The anterior degenerations and the failure of anterior end of the testis to be involved in spermatogenesis, mark the anterior regulation of the spermatogenetic process. Degenerations can be regarded as the by-product of the regulation of overactivation.
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  • 70
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    Notes: Testicular cells obtained from Manchurians were chiefly employed for the study. In the primary spermatocyte the X-chromosome presents a three-segmented structure similar to that of rats. This was not clear in our previous studies, probably due to some technical failure. Of the three segments, one frequently assumes a shape suggestive of the Y-chromosome to some authors, but this never disjoins in the first maturation division, and accordingly it cannot be regarded as a true Y. The three segments are designated as P, D1 and D2 segment, the latter two are occasionally combined to form a single D segment. The P segment presents such a great modification of shape, that it led some authors to misinterpretation. The identification of the X-chromosome was uncertain in the spermatogonial group of chromosomes, but in every case of good fixation forty-seven distinct chromosomes were found.
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    Journal of Morphology 61 (1937), S. 165-173 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations are reported which fully establish the aglomerular nature of the kidney in the following teleostean species: Hippocampus trimaculatus, Hippocampus kuda, Hippocampus hudsonius, Microphis boaja, Batrachus grunniens and Pterophryne histrio. It is possible that we are dealing with an additional aglomerular species (Microphis sp.), but this cannot be determined from the available material. All species were taken in sea water except Microphis boaja and Microphis sp., which were taken in fresh water.
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    Journal of Morphology 61 (1937), S. 285-307 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoplasm of Opalinid infusorians contains two principal components; the mitochondria and the vegetative granules of the endoplasm. A third component in the form of Golgi bodies has been previously described. Under the influence of radium radiations the mitochondria are re-orientated so that they assume a transverse polarity to the longitudinal axis of the organism. Later the mitochondria are segregated by the radiations so that they lie apart from the vegetative granules with which they are closely associated in the normal organism.
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    Notes: The development of the gonads of the marsh hawk, Circus hudsonius, Cooper's hawk, Accipiter cooperi, and the red-tailed hawk, Buteo borealis borealis has been investigated. The occurrence and relatively long persistence of the cortex on both testes of the marsh hawk is evidence of bilateral amphisexuality in this form. The embryonic condition of the ovaries is related to the degree of asymmetry in the adult organs. Nearly symmetrical, paired ovaries were found in three species and varying amounts of reduction of the right ovary in all others.The disappearance of the right oviduct in the ontogeny of the female red-tailed hawk and the occurrence of accessory gonad tissue in male embryos of the same species are described and figured. The extent of reduction of the right ovary of eleven species is described, figured and classified. The following species are listed in the above order of classification: Circus hudsonius, Accipiter cooperi, Accipiter velox velox, Accipiter atricapillus atricapillus, Falco sparverius sparverius, Aquila chrysaëtos canadensis, Buteo borealis borealis, Buteo lineatus lineatus, Buteo lagopus sancti-johannis, Cathartes aura septentrionalis, Buteo platypterus platypterus.It is concluded that two ways by which organs may disappear are realized in the right ovary and oviduct of the hawks. (1) by failure of an embryonic inductor in the case of the ovary, and (2) in the right oviduct by secondary atrophy of an originally well-developed embryonic structure.
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  • 74
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    Journal of Morphology 61 (1937), S. 433-451 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The nasal capsule of the chameleon differs greatly from that of other lizards in several respects. Cartilage is extremely persistent, particularly in the roof. The anterior chamber is produced backward to form an accessory posterior chamber. This posterior extension lies lateral to the olfactory chamber, from which it is incompletely divided by a longitudinal fold which may represent the normal concha.The organ of Jacobson is extremely reduced and occupies an abnormal position with relation to other structures. The olfactory nerves and their branches are much reduced, and the olfactory epithelium is poorly developed. The chameleon is at best a microsmatic animal.
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  • 75
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    Journal of Morphology 61 (1937), S. 473-484 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: This work was undertaken in an effort to determine the reason why the hepatic cell mitochondria of some animals show a structural response to adrenalin while others show no such reaction.It was found that those animals whose mitochondria are altered by adrenalin undergo a relatively great increase in the percentage of water in the liver. This acquisition of fluid by the liver is accompanied by a disturbance of the cell-plasma ratio of the blood. Those species whose mitochondria show no reaction to adrenalin have no change of volatile liver water, haematocrit reading, and probably have no change of total blood volume.
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  • 76
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    Journal of Morphology 168 (1981) 
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  • 77
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    Journal of Morphology 168 (1981), S. 121-135 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper describes the regeneration of the caudal axial skeleton after amputation of the tail, including about 20 vertebrae, in the gymnotoid fish Eigenmannia virescens. Seven days after amputation, a regeneration blastema developed and soft tissues degenerated. A cylinder of cartilage developed at the end of the notochord. When this cartilage was about 10 mm long (21 days), perichondral ossification began. The cartilage continued to elongate and ossification increased while osteoclasts began to destroy the cartilage ventrally. Finally, a bony rod formed and at its tip the cartilage persisted as a rod, 2 to 3 mm long. The anal fin also regenerated: Endoskeletal cartilage developed first, following by differentiation of the lepidotrichia, and finally ossification of the endoskeleton.
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  • 78
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    Journal of Morphology 167 (1981), S. 91-102 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The endemic Antarctic teleosts of the suborder Notothenioidei are bottom dwellers. They lack swim bladders, are heavier than seawater, and feed on or near the bottom. The midwaters surrounding the Antarctic continent are productive and underutilized by fishes. There is an evolutionary trend toward pelagism in some notothenioids. We discovered that the largest Antarctic fish, Dissostichus mawsoni, was neutrally buoyant. Attainment of neutral buoyancy was associated with specializations of the skeletal, integumentary, muscular, and digestive systems. The skeleton had a low mineral content and contained considerable cartilage. Scales were also incompletely mineralized. Static lift was obtained from extensive lipid (mostly triglyceride) deposits. A 2-8 mm subcutaneous lipid layer accounted for 4.7% of the body weight. White muscle also contained much lipid-23% on a dry weight basis, or 4.8% of the body weight. Microscopic examination suggested that the liver was active in lipid metabolism, although it was not an organ of buoyancy. Stellate (perisinusoidal) cells with many lipid droplets were a very prominent cytological component of the liver. These specializations made Dissostichus neutrally buoyant and capable of inhabiting the food-rich Antarctic midwaters.
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  • 79
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    Notes: The spongillid freshwater sponges asexually produce an encapsulated dormant stage, the gemmule. With release from dormancy, internal, yolk-laden, binucleate thesocytes differentiate into histoblasts or archeocytes. The histoblasts emerging first from the gemmule form the initial pinacoderm of the hatching sponge. Immunohistochemistry was employed to examine the distribution of cyclic GMP (cGMP) and cyclic AMP (cAMP) following dormancy release and during gemmule germination and hatching in the freshwater sponge, Spongilla lacustris L. Cyclic nucleotide fluorescence patterns were analyzed in relation to the distribution of cytochemically demonstrable macromolecular constituents and intracellular organelles. Twenty-four hours following temperature-activated release from dormancy, cGMP fluorescence levels are elevated in thesocytes at the gemmule periphery prior to histoblast formation. The cAMP fluorescence in the gemmule also occurs first in those thesocytes differentiating into histoblasts. Cytochemical patterns in germinating gemmules are comparable with those described by Ruthmann ('65) and Tessenow ('69). However, cytochemically demonstrable events of cytodifferentiation follow the earlier appearance of cGMP and cAMP in the histoblast precursors by approximately 12 hours. In addition, cGMP appears to be associated with the membranes of cytoplasmic organelles, possibly lysosomes or lipid inclusions, in the region of vitelline platelets and with symbiotic algae. cAMP is located primarily on the membranes of the vitelline platelets and on membranes of vacuoles involved in forming the spicular skeleton These observations suggest that cGMP and cAMP are involved in the mobilization of nutrient reserves and in ion transport during dormancy release and development from gemmules in freshwater sponges.
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  • 80
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    Journal of Morphology 167 (1981), S. 119-134 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The cranial nerves of the cutlassfish, Trichiurus lepturus, were described from their external brain origin to their most distal points. The nervus olfactorius, nervus opticus, nervus oculomotorius, nervus trochlearis, nervus abducens, nervus glossopharyngeus, and nervus vagus of Trichiurus are characteristic of teleosts. The cephalic autonomic nervous system also follows the general scheme for teleosts.Atypical patterns are exhibited by portions of the ramus mandibularis facialis, ramus mandibularis trigemini, nervus stato-acusticus, and nervus lineae later-alis. A cutaneous ramus mandibularis externus facialis arises from the ramus mandibularis; this cutaneous nerve has been recorded specifically in only certain siluroid catfish. A connection from the ramus mandibularis trigemini to the cutaneous ramus mandibularis externus facialis is present; an equivalent of this connection has been reported only in the silversides, Menidia, and the siluroid catfish Parasilurus. This nerve pattern probably represents an archaic arrangement. The nervus stato-acusticus of Trichiurus is typical for teleosts, except for a branch extending from the posterior part of the nerve; this branch sends connections to the nervus lineae lateralis and then exits the cranium via the vagus foramen. Connections between the nervus lineae lateralis and the nervus stato-acusticus have previously been reported in only the hatchetfish, Argyropelecus, and the bristle-mouth, Cyclothone. This condition may represent a specialized adaptation of certain mesopelagic teleosts having extreme vertical-migration capabilities.
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  • 81
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    Journal of Morphology 167 (1981) 
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  • 82
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    Journal of Morphology 168 (1981), S. 229-237 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Males of the cockroach, Nauphoeta cinerea (Olivier), possess a thickened secretory epithelium limited to the inner surfaces of sternites three to seven and tergites two to eight. The epithelium consists of three cell types: 1. large columnar secretory cells, 2. squamous nonsecretory cells, and 3. duct cells. Type 1 cells constitute the innermost layer and contain large nuclei and vacuoles, which are especially prominent in the epidermis of older males. This cell type may be involved in “seducin” secretion. Type 2 cells lie in the narrow basophilic zone which separates the secretory cells from the cuticle. Here, cellular boundaries are poorly defined. Type 3 cells with condensed nuclei are associated with cuticular ductules leading from the epidermis to the exocuticle. The epidermal height in the secretory zone of the sclerites approaches 40-200 μm depending on the age of the male. The changes in appearance of the secretory cells (increase in height and vacuolation) indicate heightened secretory activity. This is supported by the results obtained when extracts of these regions from different aged males are bioassayed for pheromone (Dimeo et al., '78). A striking difference in the morphology of the cuticle and epidermis of the secretory halves of sternite and tergal integument is noticeable.
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  • 83
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    Journal of Morphology 168 (1981), S. 239-245 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Mitotic waves during superficial cleavage and early gastrulation were analyzed quantitatively in Calliphora. Three consecutive patterns are present: (1) a monotonic anterioposterior mitotic gradient during early superficial cleavage; (2) a double mitotic gradient from the anterior and posterior poles during superficial cleavage, especially toward the end of the period; and (3) more complicated patterns with intermediate mitotic centers during the last superficial cleavage division and during early gastrulation. Mitotic gradients are absent in many eggs during early superficial cleavage, but they then become ubiquitous. The gradients are longitudinal; no transverse component was detected before gastrulation. Anterior and posterior gradient patterns are not mirror images of each other; mitotic activity always starts earlier anteriorly. The gradients are accompanied by a pronounced increase in interphase length. The mitotic gradients are compared with the morphogenetic gradients predicted in a current model for pattern specification in insect eggs.
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  • 84
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    Journal of Morphology 168 (1981), S. 289-295 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Marked tendinous bands lie along the lateral sides of the fingers in Varanus and Iguana and have asymmetrical roots in the metacarpal region. The radial band of each finger represents the distal extension of an oblique band arising at an ulno-dorsally located line in the proximal part of the metacarpal, whereas the ulnar bands each form a tendinous extension of an interosseus muscle bundle. The function of this metacarpo-digital system must be seen in relation to the deformations of the hand, imposed during locomotion by longitudinal rotation of the forearm. The latter motion results from the foreward and backward sway of the humerus with the elbow bent at 90°.
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  • 85
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    Journal of Morphology 168 (1981), S. 249-267 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Two aspects of the avian renal cortical microanatomy previously were unclear. The precise in situ folding patterns and orientations of the nephrons with respect to the other cortical elements had not been demonstrated. It also was not known whether certain nephron segments are supplied exclusively by either the arterial or the portal blood flow. In the present study, a new casting compound was developed to allow selective examination of the cortical components by light microscopy. Cortical nephrons at the surface of the kidney were serially sectioned and reconstructed in order to determine: (a) their relationships to the vasculature and collecting ducts; (b) the location and characteristics of the tubule segments; and (c) the primary and secondary folding patterns of the tubules. The anatomical findings were documented individually and then summarized in a comprehensive diagram of the superficial cortical microanatomy. In addition, an in vivo method was used to determine the extent of portal blood distribution to the nephron segments. It was demonstrated that renal portal blood suffuses all of the segments except for the loops of Henle.
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  • 86
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    Journal of Morphology 168 (1981), S. 331-338 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The theory of Kukalova-Peck ('78) is examined and rejected except for the hypothesis of the partially pleural origin of wings. Data suggest that the arthropods ancestral to insects left the water, and that movable precursors of the wings, possibly exopodites, were immobilized and fused with the tergum to form part of the complex paranota. Later, during insect adaptation for flight, parts of the complex paranota were separated secondarily and became wings.
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  • 87
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    Journal of Morphology 169 (1981), S. 225-242 
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    Notes: This study provides a detailed account of the development of the digestive system of larval lobsters (Homarus americanus H. Milne Edwards, 1837) and the morphological changes that occur at metamorphosis. The most dramatic of these changes involves the gastric mill of the cardiac stomach. First-and second-stage lobsters lack the medial and lateral teeth characteristic of the grinding stomach of adult lobsters. Clearly recognizable, heavily cuticularized teeth first appear in the third stage, and accessory lateral teeth do not appear until the fourth stage. In place of the teeth of the gastric mill, first- and second-stage stomachs have a series of pads and ridges which are the apparent rudiments of the teeth. The development of the gastric mill during the larval stages enables lobsters to deal successfully with the more substantial food they encounter in the benthic environment, and corresponds to the drastic change of habitat and diet which occurs at metamorphosis.Confusion about the extent of the midgut and hindgut in larval lobsters has been clarified. The results of this study have shown that the larvae have a long midgut, which lacks a cuticle, and a short hindgut with a cuticular lining, just as in adult lobsters. The junction between midgut and hindgut lies in the sixth abdominal segment in all of the first four stages, as well as in the adult.
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  • 88
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    Journal of Morphology 169 (1981), S. 275-281 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The embryonic development of the viviparous scorpion, Heterometrus fulvipes, has been followed throughout the gestation period and the successive stages of the developing embryos have been examined. The morphological features of the embryos are also described and illustrated according to their approximate age.
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  • 89
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    Journal of Morphology 169 (1981), S. 293-323 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The vascular system of the digits of the tokay is more complex than has hitherto been suspected and has a configuration which suggests it is intimately involved in the process of adhesion. Distinction can be made between lamellae (expanded scales beneath the proximal portion of the digit) and scansors (elaborations of lamellae that contain a large amount of subdermal material and therefore do not technically qualify as scales). Such a distinction is made on anatomical grounds and can be appreciated only if anatomical investigation is carried out. There are no externally obvious features by which lamellae and scansors can be distinguished, except position. Scansors are found beneath hyperextensible phalanges, whereas lamellae are located more proximally and are not subjected to digital hyperextension during locomotion. Whether this distinction can be applied to other pad-bearing geckos and to anoline lizards remains to be seen.The large sinus beneath the penultimate phalanx appears to govern the pressure within the system; the reticular blood systems of the scansors appear to manifest the pressure changes with respect to the locomotor substratum. Changes in pressure within the system probably permit the overlapping scansors to comply precisely with each other and with the substratum. The presence of a system based on fluid pressure differentials means that scansors are deformable along multiple axes at any one time, thus permitting a high degree of compliance with their entire surroundings. It is probable that changes in pressure within the system promote release from the substratum as well as compliance with and attachment to it. The mechanism of control of the system awaits further investigation.The pattern of the digital vascular complex has been considered in relation to the mode of operation of the digits during locomotion. Distal drainage of the sinus is ideally suited to the activity of hyperextension of the digits. This combination permits sequential pressurizing and depressurizing of the scansors and allows the bond to be created or broken in a gradual fashion rather than in an all-or-none manner. By avoiding sudden shifts in the pattern of dynamic loading (the bond is not broken instantaneously but sequentially), the risk of transverse instability during locomotion is lessened. The increase of loading on the other feet is thus gradual. The importance of this is discussed more fully elsewhere in a consideration of the structure and function of scansors. That the digits of the tokay are hyperextended during horizontal as well as vertical locomotion (Russell, '75, p. 463) can now be rationalized not only from the point of view of protection of the setae but also because of the manner in which the vascular system of the digits functions and is drained.
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  • 90
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    Journal of Morphology 170 (1981), S. 29-42 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retinal afferents and efferents were examined in Crotalus viridis. Retinofugal fibers were traced by injecting horseradish peroxidase (HRP) or tritiated leucine into the eye, or by removing the eye and staining degenerating axons with silver methods. Terminations were seen contralaterally in the suprachiasmatic nucleus, the dorsal and ventral lateral geniculate nuclei (extensive), the pretectal nuclei, including the nucleus posterodorsalis (a very heavy input), the nucleus lentiformis mesencephali, nucleus geniculatus pretectalis, and nucleus pretectalis, the superficial layers of the optic tectum, including the stratum zonale, the stratum opticum, the stratum griseum et fibrosum centrale and the upper portion of stratum griseum centrale, and the basal optic nucleus. Ipsilateral input reaches the intermediate portion of the dorsal lateral geniculate nucleus, a small portion of the pretectal nucleus and nucleus posterodorsalis, and the basal optic nucleus (very minimally). Retinopedal fibers were traced with the HRP method. The cell bodies lie in the ventral thalamus within the nucleus of the ventral supraoptic decussation. These neurons project primarily to the contralateral retina, but some more rostrally located neurons project to the ipsilateral retina.
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  • 91
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    Journal of Morphology 169 (1981), S. 253-257 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mesenchyme in the hind limbs of Rana pipiens tadpoles may serve as an important influence on the development of specific neural structures involved in limb innervation. Thus a histological quantification of mesenchyme was undertaken to identify landmark stages with respect to mesenchyme presence and neural events. Mesenchyme remained as a high percentage of the limb tissue until stage V (Taylor-Kollros stages, '46), after which it declined dramatically until its virtual absence after stage XI. The volume of mesenchyme, however, was greatest at stages VIII-IX. Periods of high and low mesenchyme content were correlated in time with potential limb involvement in regulating limb innervation and motor neuron loss from the lateral motor columns. This provides additional evidence for developmental relationships between events of the limb and neural tissues.
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  • 92
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    Journal of Morphology 170 (1981), S. 171-180 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this paper we document retial supply of the spinal cord and describe the arterial vascular pattern of the brain in the whale family Monodontidae. Observations are based on gross dissections of four brains, two each of Monodon monoceros and Delphinapterus leucas, and one spinal cord from M. monoceros.Vessels of the spinal cord arise from extradural retia in the neural canal. Arteries originating from the retia penetrate the dura between successive spinal roots (mainly ventral) and not in association with them, unlike radicular arteries of other mammals. Also, these vessels are uniformly distributed and contribute equally to a plexus surrounding the cord. An A. radicularis magna is not present, and neither are dìstinct anterior or posterior spinal arteries.Circulation to the brain is effected by two pairs of arteries originating from intracranial retia. The rostral pair supplies most of the forebrain (prosencephalon), whereas the more caudal pair supplies mainly the midbrain (mesencephalon) and hindbrain (rhombencephalon). The circulatory pattern is characterized by (1) complete independece of anterior cerebral arteries (no anastomoses); (2) extensive cortical supply by the anterior choroidal arteries; (3) absence of subdural communicating vessels between rostral and caudal trunks; (4) union of caudal trunks to form a small basilar artery; and (5) absence of vertebral arteries and hence of a vertebral basilar system. There are some obvious differences between subdural arteries in the Monodontidae and those in other mammals; however, their general patterns of distribution are similar, and we suggest that most of the vessels, at least in the cranium, are homologous.
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  • 93
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    Journal of Morphology 170 (1981), S. 147-169 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Optoelectronic analysis of mandibular movement and electromyography (EMG) of masticatory muscles in Cavia porcellus indicate bilateral, unilateral, and gnawing cycles. During bilateral and unilateral cycles, the mandibular tip moves forward, lateral, and down during the lingual phase of the power stroke to bring the teeth into occlusion. EMG activity is generally asymmetric, with the exception of activity of the temporalis muscle during bilateral cycles. During gnawing cycles, the mandible moves in an anteroposterior direction that is opposite that during bilateral and unilateral chew cycles. Bilateral and unilateral cycles of pellets were significantly longer than carrot. With the exception of the width of bilateral cycles, the magnitude of cycle width, length, and height during the mastication of carrots was greater than that during the mastication of pellets. Significant differences exist between EMG durations during mastication of pellets and carrots. The lateral pterygoid displays continuous activity during gnawing cycles. Significant differences also exist in the durations of EMG activity between the working and balancing side during all three cycle types. High level activity of balancing side temporalis and anterior belly of digastric (ABD) during bilateral cycles occurs during rotation and depression of the mandible during the power stroke. The temporalis apparently provides a „braking“ or compensatory role during closing and power strokes. Differences between Cavia masticatory patterns and those shown by Rattus and Mesocricetus are apparently due to differences in dental morphology, occlusal relationships, and, possibly, the poorly developed temporalis in Cavia. The large number and wide diversity of rodent groups afford students of mammalian mastication an opportunity to investigate and compare different masticatory specializations.
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  • 94
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    Journal of Morphology 170 (1981), S. 239-251 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning electron microscopy was used to characterize the external morphology of the molar surface of the mandibles of the brine shrimp, Artemia salina. Unlike many other branchiopod crustaceans, Artemia has symmetrical mandibles, ie, the molar surfaces of the two mandibles of an individual are similar in size and surface structure. Each molar area has three basic regions: the anterio-ventral region, posterio-dorsal region, and transition zone. On the anterio-ventral region there are complex, parallel furrows and ridges, which are specializations for clasping masses of fine, particulate food. The general surface of this ridged area is flat, except at the ventral and anterior edges, where there is a fringe of long projections that probably serve to retain food in the space between the paired mandibles. The posterio-dorsal region, which has simpler, more sparse cuticular projections, is adapted for reception of food. Stereomicrographs reveal that the general surface of this region is sloped and thus forms a cleft along the posterio-dorsal margin of the two apposed molar surfaces. Anatomical relstionships suggest that the cleft is an adaptation for accommodating maxillular setae that push food forward onto the mandibles. The transition zone has cuticular specializations that are morphologically intermediate between those of the anterio-ventral and posterio-dorsal regions. Three types of pores, possibly openings of glands or sensilla, were observed in the cuticle of the molar surface.
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  • 95
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An aggregation of sessile spherulocytes in the cephalon of female Gammarus setosus surrounds the ramifications of the dorsal aorta and the peripheral ganglion of the frontal organ nerve. It is not a hemopoietic organ. The spherulocytes are of three distinct varieties that may represent phases of a secretory cycle possibly synchronized with molting or reproduction. In addition, four other hemocyte types were identified in the cephalic blood sinuses: prohemocyte, plasmatocyte, granulocyte, and adipohemocyte. The cellular and nuclear dimensions of these hemocytes were analyzed. They were shown to be uniform in cell size with average cell area of 69.27 μm2, and average maximum cell diameter of 11.75 μm. The mean nuclear area and mean maximum nuclear diameter of the prohemocyte are significantly larger than those of the other cell types. The structure of the hemocyte types is described and compared to those of other crustaceans and insects.
    Additional Material: 35 Ill.
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  • 96
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 283-299 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructural features of spermatogenesis were investigated in the nudibranch mollusc Spurilla neapolitana. Sperm develop in the proximal half of numerous sac-like acini which are radially arranged within about ten ovotestis lobes. Accessory cells line the inner wall of the testicular portion of each acinus and are connected to developing sperm by numerous desmosomes. Stages of spermatid development have been divided into precup, cup, postcup, and elogate stages depending on the general shape of the nucleus. Nuclear differentiation includes the formation of anterior and posterior nuclear plaques, condensation of chromatin fibrils into nuclear lamellae, the insertion of the developing flagellar axoneme into a shallow, nuclear implantation fossa, and eventual formation of an elongated sperm head with a terminal twist. Spermiogenesis also includes the differentiation of an anterior, perinuclear structure having the characteristics of an acrosome, the appearance of peculiar arrays of ER cisternae, and the fusion of mitochondria into a large mitochondrial derivative which eventually encircles the axoneme, forming a crystalline-like periaxonemal sheath.
    Additional Material: 47 Ill.
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  • 97
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 357-372 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Feet of two-toed sloths (Choloepus) are long, narrow, hook-like appendages with only three functional digits, numbers II, III, and IV; Rays I and V are represented by metatarsals. Proximal phalanges of complete digits are little more than proximal and distal articulating surfaces. All interphalangeal joints are restricted, by interlocking surfaces, to flexion and extension. Ankle and transverse tarsal joints, however, allow extreme flexion and inversion of foot. Powerful digital flexion is augmented by several muscles from extensor compartment of leg. Intrinsic foot musculature is reduced to flexors and extensors but these, with the exception of lumbricals, are large and well developed. Choloepus uses its feet much like hooks with distal phalanges and covering claws forming the “hook” element. These hook-like appendages are seemingly best suited for supports less than 50 mm in diameter suggesting that two-toed sloths may prefer supports of this size in their natural habitat.
    Additional Material: 8 Ill.
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  • 98
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 383-399 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The perirhopalial tissue and swimming muscle of Cyanea were examined with light microscopical and electron microscopical techniques. The perirhopalial tissue is a thin, triangular septum found on the subumbrellar surface of the animal. It separates part of the gastric canal system from the surrounding seawater, and is bound on two sides by radial muscle bands and on the third, the shorter side, by a rhopalium and the margin of the bell.The ectoderm of the perirhopalial tissue is composed of large, somewhat cuboidal, vacuolated, myoepithelial cells. The muscle tails of these cells form a single layer of radial, smooth muscle. Neurons of the “giant fiber nerve net” (GFNN), which form an extensive net over the perirhopalial tissue, lie at the base of the vacuolated portion of the myoepithelial cells. These neurons are visible in living tissue. The morphology of individual GFNN neurons was examined following intracellular injection of the fluorescent dye Lucifer Yellow. The neurons are usually bipolar and free of branches. At the electron microscope level, one usually finds that the GFNN neurons contain large vacuoles. The other characteristic feature of these cells is that they form symmetrical, or nonpolarized, synapses; that is, synaptic vesicles are found on both sides of the synapse.The swimming muscle is striated and composed of myoepithelial cells. Each myoepithelial cell has several muscle tails, and those of adjacent cells are linked to gether by desmosomes. The endoderm of the perirhopalial tissue also was examined.This investigation of the organization and ultrastructure of the perirhopalial tissue and surrounding muscle was undertaken to provide essential background information for an ongoing physiological study of the GFNN neurons and their synapses.
    Additional Material: 11 Ill.
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  • 99
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 373-382 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to determine the temperature sensitive stages for sexual differentiation of the gonads in Emys orbicularis, eggs of this turtle were shifted at different stages of embryonic development from the male-producing temperature of 25°C to the female-producing temperature of 30°C and reciprocally. Based on the series of developmental stages described by Yntema (′68) for Chelydra serpentina, temperature begins to influence sexual differentiation of Emys orbicularis at stage 16, a stage in which the gonads are still histologically undifferentiated. Its action lasts over the first steps of histological differentiation of the gonads. The minimal exposure at 25°C required for male differentiation of all individuals extends from stage 16 to somewhat before stage 21. For 100% female differentiation, incubation at 30°C must be longer, from stage 16 to somewhat before stage 22. Shorter exposures at 25°C or 30°C during these periods result in different percentages of males, females, and intersexes. Our results show that there is a critical stage (stage 16) which is the same for both male and female differentiation of the gonads. The thermosensensitive periods are rather long, corresponding to 11-12 days at 25°C and 30°C.
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  • 100
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 271-272 
    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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