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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925) 
    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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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 517-557 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An early segregation of germ cells and migration through a germ track into the gonad does not occur in the albino rat. The germ cells are produced only from the peritoneum of the genital region and their earliest formation is coincident with the thickening of the coelomic epithelium to form the genital ridge. This takes place eleven days after insemination in embryos of approximately 18 somites. Germ cells continue to form from the peritoneum during the early development of the gonad. The peritoneum of this region also produces mesenchyme, smaller cells of the gonads, and the germinal epithelium.The argument for the specific character of the germ cells in vertebrates and their continuity from the egg is based largely upon assumption, and not upon substantial observations, and must be discarded. Germ-cell origin is a problem of cellular differentiatio, and not of early segregation.
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  • 3
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1925), S. ii 
    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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  • 4
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1925), S. 191-216 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Painted turtles, gopher tortoises, and terrapins were fed on various mixtures of sand, salts, dextrin, casein, cod-liver oil, wheat, eggs, lettuce, and meal worms. Each individual was weighted weekly for about a year and then killed for analysis, the water, ash, nitrogen, and fat being determined. Some individuals increased in weight as much as 75 per cent, others lost weight. Judged by growth and chemical analyses, the food requirements of chelonians, as representative poikilothermal vertebrates toward nutritive substances (including vitamines) are similar to those of homoiothermal animals.
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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1925), S. 267-281 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Of the eggs laid by Fasciolaria about 1 per cent develop into veligers, about 2 per cent more undergo a few cleavage divisions, and about 97 per cent do not divide at all. The 99 per cent that fail to develop normally are ‘swallowed’ by the veligers. This study concerns itself chiefly with the ova that do not divide. Notes on normal development and on the ova that undergo atypical cleavage are included.All of the ova are found to be typical when passed from the ovary. To each ovum one to several sperms become attached at the vegetal pole in the region of a mass of undifferentiated protoplasm - the ‘polar mass.’ A fertilization cone forms in each ovum and a fertilization membrane. In typical development a yolk lobe is formed, the sperm enters in the usual way, and fertilization is completed as in many other mollusks. In 97 per cent of the ova the yolk lobe is not formed and the sperm does not enter. In these cases the wall of the egg nucleus remains intact a long time. The nucleus itself and the ‘polar mass’ sink into the egg and meet at the center. Then the nuclear wall disappears and an atypical diaster is formed. However, cleavage is not begun and the chromosomes form vesicles that remain near the center of the ovum until it is ‘swallowed’ and digested by the veliger.
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The blood of Perophora viridis is found to contain six types of cells: (1) Green cells, which have green-colored fatty bodies embedded in clear cytoplasm. (2) Orange cells, with orange-colored bodies of unknown composition in the cytoplasm. (3) Colorless berry-like cells, with fluid-filled vesicles in the cytoplasm. (4) Granular amoeboid cells. (5) Compartmental amoeboid cells, which have box-like vacuoles containing brownian granules of a fatty substance. (6) Vesicular, signet-ring type of cell having a single large vacuole. The cytological structure of these cells and their reaction to various dyes are described.An effort has been made to homologize the types of cells found in the blood of other ascidians with those found in Perophora.It is concluded that the variety of colors found in the cells of ascidian blood is due to the varying chemical states of the vanadium-containing chromogen present in the cells.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926) 
    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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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 111-141 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Disintegration in killing agents was studied throughout development. In the unfertilized egg and cleavage stages the death gradient runs from animal to vegetal pole. In the late blastula stage the future dorsal surface and future point of gastrulation show heightened susceptibility. The gastrula has a gradient from anterior to posterior end along its dorsal surface, with a slight reverse gradient around the blastopore; lateral and ventral regions are least susceptible.Before and after the appearance of the neural groove, the dorsal surface shows increased susceptibility with gradient in it from anterior to posterior end. The neural tube is highly susceptible, with a death gradient from anterior to posterior end and a slight reverse gradient at its posterior end.During late stages and in the larva the double gradient is present; death begins at the two ends and progresses backward from head, forward from anus; from the former most rapidly. The least susceptible place is near the posterior end. The posterior reverse gradient is less developed in the lamprey than in other vertebrate embryos, due, probably, to its lack of a tail bud.Assuming that death differences indicate differences in rate of activity, it appears that such differences in activity may be causes and not results of developmental processes, for the development of certain parts (dorsal surface, blastopore, central nervous system) is indicated by heightened activity before it is evident morphologically.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 83-109 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The summary of this paper is as follows:1A critical review of the developmental evidence shows that the branchial pouches are formed in cephalocaudal sequence subsequently to the segmentation of the dorsal mesoderm.2The pouches interrupt a continuous sheet of mesoderm to form the branchial arches.3The arches when formed do not correspond topographically to the dorsal somites.4Branchiomerism does not therefore coincide with somitic metamerism.3The branchial structures do not support the theory of head segmentation.3The nervi trigeminus, facialis, glossopharyngeus, and vagus cannot be regarded as segmental nerves.3There is no evidence that branchial pouches or arches have been elided from the series.3The problem of meristic homology is briefly discussed.
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  • 10
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The claspers of Centrina are adnate with the pelvic fin and bear a spine as in other Spinacidae. Mustelus canis resembles M. lunulatus rather than M. vulgaris. The claspers of Chiloscyllium end in a pointed spike. Pseudotriakis resembles the Carchariidae. The three North American Atlantic species of the genus Raia are considered, and R. laevis and R. erinacea are placed in the pseudogenus containing R. batis, and a new pseudogenus erected for R. ocellata. A gross and histological account is given of the Cowper's glands of Homo, and they are shown to be homoplastic with clasper glands, similar in structure, arrangement, development, and function.
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  • 11
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the golden-mantled ground-squirrel, Callospermophilus, a spatulate glandular area has been noted in the skin of the back. It has been found in the following species: C. l. lateralis, C. l. arizonensis, C. l. caryi, C. l. saturatus, C. l. tescorum, C. c. chrysodeirus, and C. bernardinus. Probably it is common to the genus.The individual glands making up this area are modified and enlarged sudoriparous glands. They are divided into a tightly coiled and branched fundus, a large sinus, and a duct which passes caudad and outward to its exit at the surface.The glands secrete a strongly smelling oil, which is probably left on vegetation and other objects in the animal's environment and serves as a source of information to other members of the species. The glands are more active in spring and summer than in winter. They are stimulated by excitement. While present in both sexes, both adult and juvenile, they are best developed in adult males.Callospermophilus has three anal glands. These have flat-topped, straight-sided nipples which are protruded from the anus if the animal is frightened. A milky substance with a very weak odor can be extruded.
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  • 12
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The study is divided into three parts. Part I deals with the chromosome number and morphology in the amniotic cells of rabbit embryos. The number of chromosomes has been found essentially constant in amniotic cells of young, but more variable in older embryos. The somatic number is 44. Part II deals with the chromosomes of race crosses (Flemmish Giant X Polish) in which the homologous chromosomes were found to be alike. Part III deals with spermatogenesis. There are forty-four chromosomes in spermatogonia, and twenty-two in primary spermatocytes. The sex chromosomes are of the usual X-Y type.
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  • 13
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 1Monovalent cation salts induce reversal in the direction of the stroke of the cilia; bivalent and trivalent cation salts with a few exceptions do not. Some acids induce reversal, others do not.2The duration of reversed action varies with the kind of salt and with the concentration. As the concentration increases, the duration of reversed action increases to a maximum and then decreases to zero.3Bivalent and trivalent cation salts neutralize the effect of monovalent cation salts. The relative amount required varies with the kind of salt used and with the concentration.4The amount of a given salt required to neutralize another salt is not proportional to the concentration of the salt neutralized. Weber's law does not hold.5The results seem to indicate that ciliary reversal is associated with differential adsorption and consequent changes in electric potential, but that there are also other factors involved.
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  • 14
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A special type of cell, called ‘Lichtzellen’ by Hesse, was found in the photosensitive regions of the earthworm. Wherever the epidermis is most sensitive to light these cells are most abundant. They are found in the epidermis of all segments of the body and also in nerve enlargements of the prostomium and the caudal segment, but the intersegmental and ventral regions of the different segments, except the more distal ones, contain none of them. They are supplied by nerves and each contains a characteristic inner structure, the optic organelle, composed of a large central hyaline structure, the lens, which is surrounded by a dense network of nerve fibrillae, the retinella. In hanging drops the lens was found to focus light in the region of the retinella irrespective of the direction of the rays.These cells are similar in structure and function to the visual cells in leeches. Available data indicate that these cells function as photoreceptors and that the fibrillae of the retinella are the direct receptors of light stimuli.Pigment is not associated with the photoreceptors in a way that suggests direct functional relationship, but there is a subepidermal pigment layer through which pinhole windows admit light along the path of nerves to each of the nerve enlargements containing photoreceptor cells. These windows open in such directions as to determine the direction of withdrawal of the worm.
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  • 15
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of removal of the liver has been noted in fishes, frogs, and turtles. As in the higher vertebrates, removal of the liver produced a fall in blood sugar and a loss in muscular tone. The lower vertebrates failed to respond to intravenous injections of glucose, as do the birds and mammals. They also fail to respond to maltose or levulose. The liver maintained the blood-sugar level in the lower vertebrates, which is necessary for the maintenance of life.The mechanism of carbohydrate metabolism in the lower vertebrates may be different from that in the higher ones, in that glucose, when injected intravenously, apparently exercises a progressively less beneficial effect on the characteristic hypoglycemic condition which follows the removal of the liver of mammals and cold-blooded vertebrates.
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  • 16
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1925), S. 239-265 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reports experiments with Fundulus heteroclitus to modify larval development by means of ultraviolet radiation. Eggs were exposed to radiation at various intervals after fertilization for varying periods of time. The results accord with previous work on fish teratology, and the developmental types obtained are essentially similar to those produced by chemicals, cold, and hybridization. The deviations from normal development occur in the same body regions as do those in other vertebrates whose early development has been modified by the action of radiation (x-rays, radium, etc.).The results of these experiments indicate that there is a non-specificity in susceptibility relations with the production of similar types of monsters for widely different reagents. That these eggs are differentially susceptible to the action of ultraviolet radiation is indicated by the fact that those regions which have the highest metabolic activity when an inhibiting influence is active are the ones most generally affected. Thus modifications of the nervous system, sense organs, circulatory system, tail region, and body axis result, respectively, in the production of varying degrees of cyclopia, inadequate circulation, short, stubby or bent, non-motile tails (some bifid), and anterior twinning.As these modifications may be produced by applying inhibiting influences during the first few minutes after fertilization, it is evident that there is in the egg at this stage some constitutional or physiological basis which determines early differences in susceptibility of its various parts.
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  • 17
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 427-439 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Webbing of toes or fingers in man is produced by a local arrest of development, causing retention of the normal embryonic webbing. This type of digital fusion involves only the skin, the skeleton being unaffected. The extensor tendons of the toes may sometimes be fused.Webbed digits occur normally in some marsupials, rodents, and insectivores, in a number of lemurs and catarrhines, and in the siamang and gorilla. They also may occur in varying degree in other Primates, notably Hylobates. An analysis of five new pedigrees together with those already published demonstrates that webbing of toes in man may be inherited in either a mendelian or sex-linked manner. In one case this character follows the course of the Y-chromosome.
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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: 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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  • 19
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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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  • 20
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    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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  • 21
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    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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  • 22
    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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  • 23
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    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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  • 24
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    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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  • 25
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    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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  • 26
    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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  • 27
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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
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  • 28
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    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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  • 29
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    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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  • 30
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    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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  • 31
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    Journal of Morphology 60 (1937), S. 361-377 
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    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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  • 32
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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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  • 33
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    Journal of Morphology 60 (1937), S. 445-458 
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    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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  • 34
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    Journal of Morphology 60 (1937), S. 489-519 
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    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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    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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  • 36
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    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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  • 37
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    Journal of Morphology 61 (1937) 
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  • 38
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    Journal of Morphology 61 (1937), S. 223-255 
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    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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  • 39
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    Journal of Morphology 61 (1937), S. 385-397 
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    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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  • 40
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    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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  • 41
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    Journal of Morphology 61 (1937), S. 495-523 
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    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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  • 42
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    Journal of Morphology 151 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 43
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    Journal of Morphology 151 (1977), S. 81-109 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: (1) In an animal where the corpus allatum complex is inhibited by glucose feeding, the ovariole develops to a certain size without yolk deposition in the oocytes. Histologically this can be registered as: (a) Lipid spheres are found in the young oocytes in the vicinity of the Balbiani body (as in young normal oocytes). However, this lipid decreases in amount and “new” lipid (from the fat body via haemolymph) is not deposited in the later oocytes. (b) No carbohydrate/protein yolk is formed. (c) Glycogen is not synthesized in the oocytes. (d) The follicle cells aggregate glycogen instead of lipid. (e) No qualitative differences have been observed regarding the contributions from the tropharium (the so-called Type 1 vacuole, ribosomes, mitochondria, annulated lamellae: Schreiner, '77).(2) Implantation of a corpus allatum complex results in deposition of lipid, carbohydrate/protein and glycogen yolk. However, the restoration period differs histologically from the normal development as: (a) Glycogen appears in the oocyte earlier than normal, i.e., at Stage 4, while normally at Stage 6′. (b) Glycogen appears in the nutritive tube adjacent to the interfollicular plug cells. (c) Both the inner and outer layer of the ovariole sheath contain glycogen, the outer layer contains lipid spheres as well.
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  • 44
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    Journal of Morphology 151 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 45
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    Journal of Morphology 151 (1977), S. 187-211 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The odontophore and connective tissue-filled portion of the radular sac (called the “collostyle”) of the slug, Limax maximus, were examined by light and electron microscopy. While both of these structures grossly resemble vertebrate cartilage, neither is composed of a type of tissue with the microscopic appearance and histochemical properties of cartilage. The roughly U-shaped odontophore possesses a thin capsule composed of connective tissue. The parenchyma of the odontophore consists of modified muscle cells which are organized into irregular groups by incomplete trabeculae composed of conventional muscle cells. The odontophoral cells are variable in size; they contain glycogen-filled “cores” as well as bundles of peripherally located filaments resembling myofilaments; and they are innervated like muscle cells. The nuclei of the cells are located eccentrically in the glycogen-filled portions of the cells and typically contain prominent nucleoli. The nuclei are surrounded by multiple small Golgi complexes and pleomorphic dense bodies resembling lysosomes. The extracellular matrix of the odontophore is very sparse and contains glycogen and fibrillar material but no histochemically demonstrable acidic mucosubstances. The collostyle consists of a gelatinous type of tissue somewhat like vertebrate mucoid connective tissue. The abundant extracellular matrix contains cross banded filaments, a flocculent material disposed in wavy indefinite strands, and small electron-dense particles. The matrix contains histochemically demonstrable neutral and weakly acidic mucosubstances. The cell population of the collostyle includes solitary muscle cells and fibrocytes containing large quantities of glycogen.
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  • 46
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    Journal of Morphology 151 (1977), S. 213-237 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This ultrastructural study on the localization of Ca+2 in developing skeletal muscle indicates that the formation of calcium-accumulating components begins during embryonic development. Both oxalate and pyroantimonate techniques are used to localize Ca+2 in distinct cellular components of chick pectoral and sartorius muscles. Two major sites for Ca+2 accumulation are present in ultrathin sections of embryonic and post-embryonic muscles: the terminal cisternae of the sarcoplasmic reticulum and specific lines in the I-bands. Calcium oxalate-accumulating vesicles are present in the smallest recognizable myotubes at the twelfth day of incubation, but calcium-accumulating components are not seen at myofibrillar I-band sites until the fourteenth to seventeenth days of incubation. The fact that myofibrils first form and later in development accumulate a Ca+2-binding component suggests that this Ca+2-binding component is not necessary for the formation of myofibrils, but is added to myofibrils before hatching to serve a probable regulatory role in contraction.
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  • 47
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    Notes: This report is an ultrastructural analysis of the organization of the isolated oral apparatus of Tetrahymena pyriformis, strain WH-6, syngen 1. Attention has been focused on the organization of microtubules and filaments in oral apparatus membranelles. Oral apparatus membranellar basal bodies were characterized with respect to structural differentiations at the distal and proximal ends. The distal region of membranellar basal bodies contains the basal plate, accessory microtubules and filaments. The proximal end contains a dense material from which emanate accessory microtubules and filaments. There are at least two possibly three different arrangements of accessory structures at the proximal end of membranellar basal bodies. All membranellar basal bodies appear to have a dense material at the proximal end from which filaments emanate. Some of these basal bodies have accessory microtubules and filaments emanating from this dense material. A possible third arrangement is represented by basal bodies which have lateral projections, from the proximal end, of accessory microtubules and filaments which constitute cross or peripheral connectives. There are at least three examples of direct associations between oral apparatus microtubules and filaments: (1) filaments which form links between basal body triplet microtubules, (2) filaments which link the material of the basal plate to internal basal body microtubules, (3) filaments which link together microtubule bundles from membranellar connectives. KCI extraction of the isolated oral apparatus resulted in the selective solubilization of oral apparatus basal bodies, remnants of ciliary axonemes and fused basal plates. Based on their response to KCl extraction two distinct sets of morphologically similar microtubules can be identified: (a) microtubules which constitute the internal structure of basal bodies and ciliary axonemes, (b) microtubules which constitute the fiber connectives between basal bodies.
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  • 48
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    Journal of Morphology 151 (1977), S. 353-361 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural analysis of initial development of actinotrichia, the skeleton anlage of the pelvic fin buds, was performed on the rainbow trout, Salmo gairdneri. It shows that the first actinotrichial rudiments appear in the subepidermal space of the pseudoapical cap. No mesenchymal cell bodies or their filopods are present. Hyaloplasmic protrusions of the basal epidermal cells are seen in the subepidermal space, limited by a dermoepidermal boundary reduced to a discontinuous thin adepidermal lamina without a collagenous layer. These morphological data suggest that the epidermal pseudoapical cap probably initiates the development of actinotrichia. Later, mesenchymal cells invade the subepidermal space and are probably involved in the further growth of actinotrichia.
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  • 49
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    Journal of Morphology 151 (1977), S. 397-417 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Synaptic organization of the nucleus rotundus was studied with the electron microscope in three teleost species belonging to the same order. In spite of the different histological organization (non-laminated, incompletely laminated, and laminated), the same kinds of axon terminals (S and F) are observed in all species. A fibrous layer which is clearly formed only in the laminated nucleus is composed of F1 terminals and dendrites from a layer of small cells. The same kind of synapses formed between F1 terminals and dendrites of small cells are also found among glomeruli in the non-laminated and incompletely laminated nuclei. The main constituents of glomeruli are S and F2 terminals and dendrites of large cells in the non-laminated and incompletely laminated nuclei, and are S terminals and star-like structures which correspond to the tips of the dendrites of large cells in the laminated nucleus. The star-like structure contains numerous mitochondria and clusters of small polymorphic vesicles. Some of the vesicles aggregate at thickened cell membranes of the structure as in presynaptic dendrites.
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  • 50
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    Journal of Morphology 152 (1977), S. 247-279 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The intrinsic organization of medial cortex in snakes, primarily of the genera Natrix and Boa, was studied using Golgi and electron microscopic techniques. The area has three distinct layers, each containing a characteristic population of neurons. Stellate cells comprise a relatively small population of neurons with their somata and dendrites restricted to layer 1, the most superficial layer. Their axons course horizontally in layer 1. Candelabra cells form the largest population of neurons in medial cortex. Their somata lie densely packed in layer 2 and are joined by specialized junctions. Ascending dendrites extend from the somata into layer 1. They consist of spine-free proximal segments and spine bearing distal segments. Descending dendrites extend from the somata into the upper half of layer 3. The proximal segments bear few spines but branch into several tapered, distal segments which have a moderate covering of spines. One or two axons originate from the descending dendrites and descend through layer 3. The axons bear collaterals in the deep half of layer 3 and eventually bifurcate in the alveus. The medial branches run into the septum; the lateral branches course through other cortical areas. The axons bear frequent varicosities within medial cortex. Periventricular cells lie in the deep half of layer 3, either singly or in clusters. Their ascending dendrites extend radially into layer 1 where they branch into distal segments which resemble those of the candelabra cells. Their descending dendrites arborize horizontally in the alveus and bear a moderate covering of spines. Ependymal cells line the ventricular surface and send radial processes through the area's depth bearing lamellate processes.
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    Journal of Morphology 152 (1977), S. 329-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sex-linked mutation fs(1)42 was induced by ethyl methane sulfonate. It has no effect on either the external morphology or longevity of adult hemizygotes or homozygotes. Heterozygotes and hemizygotes are fertile, but homozygotes are sterile. Egg chamber development proceeds through stage 8, and thereafter chambers degenerate. Dying follicle cells are seen in chambers at all positions in the ovarioles. Profollicle cells also die within germaria, and clusters of sister cystocytes take longer than normal to receive their coverings of follicle cells. Egg chambers in the vitellarium contain only about 60% the normal number of follicle cells, these generally have greater lateral dimensions, and their nuclei and nucleoli are also larger than normal. The follicular envelope of mutant chambers often contains gaps through which cystocytes send cytoplasmic projections. Abnormalities seen in development of the fs(1)42 oocyte are likely to be due to its envelope of defective follicle cells.
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  • 52
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    Journal of Morphology 152 (1977), S. 363-379 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Reproductive organs of four botryllid ascidians, Botryllus primigenus, Botryllus schlosseri, Botrylloides violaceus and Botrylloides leachi, were studied histologically. In every species, the egg follicle consisting of an egg and its inner and outer follicles, is attached to the follicle stalk, the vesicle being composed of a flat epithelium, which in its turn is connected to the atrial epithelium or to the brood pouch specialized from it. In B. schlosseri, the egg is ovulated into the atrial cavity and remains there held by the brood cup, of which the inner epithelium is derived from the follicle stalk and the outer one from the atrial epithelium. In B. primigenus, the brood pouch develops as a diverticulum of the atrial cavity, around the entrance of which a fold differentiates from the atrial epithelium and closes the pouch during embryogenesis. In both species of Botrylloides, the brood pouch is formed by the outgrowth of the thickened atrial epithelium into the blood space, the entrance of which is closed during embryogenesis. The discarded outer follicle completely disintegrates soon after ovulation in B. schlosseri, but part of it remains throughout embryogenesis in the blood space in B. primigenus or projecting into the interior of the brood pouch in Botrylloides. In B. primigenus, the testis, when it accompanies the egg follicle, is placed at the bottom of the brood pouch and the sperm is shed through the pouch prior to ovulation. In B. schlosseri and the Botrylloides species, the testis is located independently from the egg follicle and the sperm matures after ovulation.
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  • 53
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    Notes: The cells of the follicular epithelium of the ovarioles of the mosquito, Aedes aegypti (L.), and of the stable fly, Stomoxys calcitrans (L.), have been found to be interconnected by cytoplasmic bridges. Cytoplasmic bridges have been reported between sibling gamete cells of both male and female insects, but these bridges have not been previously reported to exist between somatic cells of insects.
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  • 54
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    Notes: An unusual organelle in the oocytes of the marine mud snail Ilyanassa obsoleta is described and called a polymerosome, because of its several components. Polymerosomes appear at the beginning of vitellogenesis and persist, in part, through postvitellogenesis. The persistent part is similar to an organelle that has been described by other workers in the vegetal region and the polar lobe of the Ilyanassa egg.
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  • 55
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    Journal of Morphology 153 (1977) 
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  • 56
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    Journal of Morphology 152 (1977), S. 315-327 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An analysis of mechanical and architectural aspects of three hamstring muscles in the cat, semitendinosus (ST), semimembranosus anterior (SMa), and semimembranosus posterior (SMp), is presented based on whole muscle tetanic tension profiles. Length-active tension curves for each muscle were obtained by electrical stimulation of the whole muscle with a train of stimuli at 100 pulses per second (pps) for 600 milliseconds.Information from motion picture analysis (Goslow et al., '73) and electromyographic (EMG) activity (Engberg and Lundberg, '69) as seen during the step cycle is combined with analysis of joint torques to present a picture of the differential functions of the three muscles. The length-active tension characteristics of ST and SMa are such that they develop high amounts of tension throughout their physiological excursions. Maximal tension is produced over a much more limited range by SMp. A division of labor for the three muscles is proposed: the one-joint SMa is shown to be a primary hip extensor whose action facilitates smooth oscillation of the leg. Torque and electrical activity during the step cycle indicate the two-joint ST is a primary knee flexor. The more limited range of maximum torque and variable EMG pattern of the other two-joint muscle, SMp, relate to the fact that it has primary activity during high speed gaits when it may act to initiate spine flexion and assist in hip extension.Excursion and activity data have led to the conclusion that biarticular muscles (ST and SMp) may benefit from the combined action of two joints to maintain near maximal tension and torque during active phases of the step cycle. Thus, biarticular muscles may have evolved as much for the mechanical and physiological benefits they derive as for two-joint action itself.
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  • 57
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    Journal of Morphology 152 (1977), S. 381-400 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Oogenesis has been investigated utilizing both light and electron microscopical techniques in the squid, Loligo pealei. This complex process has been divided into five stages according to the structure of the follicle. Because of the highly coordinated differentiation of the follicle cells (and follicular syncytium) and the oocyte, their development is described in concert. Specific attention is given to the contribution of the follicular syncytium to vitellogenesis and the formation of the extracellular egg envelope or chorion. Our observations indicate heterosynthetic yolk production and the synthesis of the secondary envelope by the follicular syncytium.
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  • 58
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    Journal of Morphology 153 (1977), S. 39-79 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A recently presented model of tongue projection dynamics is used to generate a series of predictions concerning morphologies to be expected under selection for increased distance of projection, increased speed of projection, and increased directional versatility. A general understanding of biomechanical events and the model are used as points of departure for making specific predictions concerning details of structure in skeletal, muscular and connective tissue components of the tongue and associated structures. Comparative methods are used to examine these predictions in the genera of plethodontid salamanders. These salamanders are known to project their tongues to different degrees, and this knowledge is used to test the hypotheses concerning morphological specialization. Three distinct groups of plethodontid salamanders have evolved specializations for long distance projection, and these genera differ from one another in important ways in respect to specific character complexes. For example, the tropical genera and Hydromantes use CBII as the major force transmission element in the skeleton, while Eurycea and its allies use CBI in this role. Hydromantes differs from both in having a uniquely proportioned and structured hyobranchial skeleton and associated musculature. Less extreme specializations for tongue projection are found in different combinations in three other groups. Finally, two distinct groups of generalized species having only limited tongue projection capabilities are recognized, each having a unique complex of inter-related features. Each of these eight groups is recognized and characterized as a functional mode, and hypotheses concerning the biomechanical meaning of the character complexes of each are formulated.
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  • 59
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    Notes: The mechanical properties of the whole muscle and fast-twitch muscle units of the cat hindlimb pretibial flexors have been explored and related to normal locomotion. Tibialis anterior (TA) is parallel-fibered and functionally crosses a single joint, the ankle, whereas extensor digitorum longus (EDL) is pinnate and spans the ankle, knee, metatarsophalangeal and interphalangeal joints. The active tetanic tension of TA remains near its peak value over a range of muscle lengths associated with normal ankle movement. In contrast, the length-tension curve of EDL is sharply peaked. However, normal corollary action of the knee, ankle and metatarsophalangeal joints during stepping minimizes EDL's excursion and maintains it at or near a length optimal for peak tension development. EDL is capable of producing synchronous but sterotyped digit and ankle movements while TA provides for independent ankle flexion at all relevant joint angles.The mechanical properties of 84 TA and 98 EDL fast-twitch muscle units were studied by measuring twitch contraction time (≤45 msec), peak tetanic tension, response to repetitive stimulation, and contractile fatigue resistance during electrical stimulation of single alpha axons, functionally isolated from ventral root filaments. These mechanical properties were essentially similar for both muscles with the exception of mean peak tetanic tension which was 30% lower for TA units (14 gm-wt) than for EDL units (20 gm-wt). A high proportion of units in both muscles demonstrated fatigue resistance which is reflective of the repetitive, phasic demand upon these muscles during locomotion.
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  • 60
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    Journal of Morphology 153 (1977), S. 263-297 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey is made of some ultrastructural features of the developing cornea of Macaca mulatta. The observations are confined to the anterior central area, starting with the lens vesicle stage and progressing through midgestation, when the morphologic characteristics of the cornea are fully established. Subepithelial filaments and some partially aggregated collagen fibrils are present in the earliest embryo and are of a size and appearance similar to those in the future vitreous cavity. Epithelial secretory activity points to, but does not prove direct contribution to the deposition of the acellular matrix components beneath it. No trace of a structured, orthogonal collagenous stroma can be visualized. The primitive endothelium forms prior to the fibroblast invasion of the distended filamentous matrix. Bowman's layer has undoubted epithelial contributions. Its aggregated collagen fibrils have approximately the same diameter as those of the anterior stroma. Intraepithelial appearance of single nerve fibers and fascicles takes place during the first trimester of gestation, as soon as the two continuous epithelial layers are formed. Terminal areas approach closely to the basal cell's nucleus, without touching it. The plasmalemma of the invaginating nerve fiber is surrounded by that of the epithelial cell in a mesaxon-like manner, with occasional gap junctions uniting adjoining neural and epithelial cell membranes. The fetal neurites contain microtubules, some clear vesicles and dense vacuoles resembling those of mature monamine and non-monamine neurons. Mitochondria are small and compact, their presence indicating a high rate of metabolic activity in the immature terminal area.
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    Journal of Morphology 153 (1977), S. 333-353 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structural features of sinus hair follicles in Sorex unguiculatus were studied by macroscopic dissection, serial section light microscopy and electron microscopy. The shrew has about 540 sinus hairs regularly arranged on the snout. The maxillary nerves innervating them are extremely thick, while the optic nerves are very thin. Thus the follicle must be one of the most important sense organs in this animal. In the follicle the ring sinus is well-developed and the trabeculae of the cavernous sinus are reduced in number and thickness. The ring bulge is not a unified structure but a pair of bodies which consist of head, stalk and attachment plaque. It is characterized by the presence of numberous thick collagen fibrils (400 nm) and appears to be mechanically rigid. Lanceolate nerve terminals, free endings, Merkel cells with nerve terminals and unmyelinated fibers are observed, but encapsulated endings are lacking in and around the follicles. Straight lanceolate terminals on the posterior side of the follicle are thick and three-sided in cross section, while those on the anterior side are thin and two-sided. Free endings are located on the anterior side of the follicle. These and other findings are discussed on the basis of the assumption that the Sorex sinus hair follicle is more specialized as a vibrating system than in other mammals.
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  • 62
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    Journal of Morphology 153 (1977), S. 371-385 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Neurosecretory cells are arranged in 16 NSC centers in the different regions of the brain of O. tholozani. The component cells belong to 13 different types, of which five types are paraldehyde fuchsin positive and the remaining types are negative. Three of these cell types are here described for the first time. Some of these NSC show an affinity to certain localities inside the brain. Cells comprising a neurohaemal organ were found near the exit of the esophagus.
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    Journal of Morphology 153 (1977), S. 419-425 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Yolk platelets in differentiating embryonic amphibian cells degrade by a membranous “unraveling” or “delamination” process. Acid phosphatase activity was demonstrated at the peripheries of those platelets which were in the process of degrading and thus this lytic enzyme appears to be involved in the breakdown process. We believe that this relationship provides a means by which early cells obtain the nutrients necessary for early differentiation.
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  • 64
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    Journal of Morphology 153 (1977), S. 467-477 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The coelomocytes of Lumbricus terrestris have been classified and described, based on Wright's stained preparations and on living cells. The five major categories consist of basophils, acidophils, neutrophils, granulocytes and chloragogen cells. Both the acidophil and chloragogen cell groups contain two subgroups. Granulocytes also exhibit heterogeneity with respect to staining properties of granules. Some possess acidophilic granules, some basophilic granules, and others contain both types. Granules of acidophils have been observed to be occasionally excreted from the cells. All cell types, with the exception of chloragogen cells, produce pseudopodia and are capable of phagocytosis, a vital component of the earthworm's immune response.
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  • 65
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    Notes: Newly metamorphosed Kenyan reed frogs, Hyperolius viridiflavus ferniquei, are able to regenerate amputated digits. The terminal digital pad is also completely reformed. Differentiation of the regenerating digital pad was studied by scanning electron microscopy. External differentiation of the digital pad began late in the second postamputational week with the appearance of small patches of specialized epidermal cells on the ventral surface of the regenerating digit. The differentiation of the pad spread out radially until late in the fourth week, when its overall shape approximated that of the normal digital pad. The appearance of patches of digital pad epidermis on the ends of spike regenerates arising from the forearm was also confirmed.
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  • 66
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    Journal of Morphology 153 (1977), S. 427-460 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The objectives of this research were to investigate the morphology of the thoracic skeleton and muscles of the mosquito, Culiseta inornata (Williston). The results are presented in 25 text figures and descriptions of each skeletal part and muscle. Undescribed exoskeletal structures are the postmediotergite, intersegmental cleft on the caudal margin of the metapleuron, and the parascutellar process. This process is considered a homologue of the fourth axillary. The acrotergite 2 and subalifer were identified. The prescutum has been called the paratergite by previous authors. The morphological basis for self amputation of legs is described. Undescribed parts of the endoskeleton are: lateral arm of sternal apophysis 1 and its socket on the mesal surface of coxa 1, furcopleural apodeme on sternal apophysis 1, precoxal and postcoxal apodemes arising from the ventral pleural arm, upper and lower laterotergite apodemes on the postnotum, and the pleural and intersegmental apodemes for attachment of halter muscles. Seventy-two muscles are illustrated with their attachments and the origin, insertion, and action of each is described. Ten of the muscles are newly described for the mosquito. There are no muscles inserted on the subalare, second axillary, or third axillary.
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  • 67
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    Journal of Morphology 154 (1977) 
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  • 68
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    Journal of Morphology 154 (1977), S. 1-17 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The results of reversing the polarity of the middle gastric region in Hydra viridis with multiple-gastric region grafts (3grp animals) are contrasted to previously reported results on comparably elongated animals (3g animals) whose middle gastric regions retain their original polarity. The middle gastric regions of 3grp animals are also bisected (the animals are hemisected) at various times after grafting. Compound heads and compound feet form at the proximal and distal graft borders, respectively, in nearly all 3grp animals. The regeneration of structures at points is a built-in property, not influenced by reversing the polarity of pieces during grafting. Regeneration is accelerated when comparable wound surfaces are brought together by grafting with reversed polarity. Graft rejection is influenced by the total length of an animal and distances from terminal structures, but not the polarity of pieces. Budding is also influenced by total length and distance, but is dependent on polarity and diminished by head regeneration. When fresh wound surfaces are made on the middle piece of 3grp animals, an initial refractory period, during which head and foot (but not budding region) regeneration is inhibited in about half the animals, is followed by an indefinite period in which head and foot regeneration is permitted (and budding region regeneration prevented). Hemisection does not interfere with the regeneration of compound structures already in progress. These results are interpreted in terms of theories of competence, negative dominance, threshold (positional value), inhibition (positional signal), and induction (positive or constructive dominance, stimulation or enhancement).
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  • 69
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    Notes: Neurosecretory A cells in the pars intercerebralis of O. fasciatus were identified at the ultrastructural level. Fine structural study of the A cells of female insects during the period of production of the first batch of eggs revealed that these cells undergo qualitative and quantitative changes during the first eight days of adult life. The A cells appear to be inactive in the newly emerged females. There is a significant depletion of neurosecretory granules (NSG) in the perikarya in the 2-day-old females followed by an increase and decrease in the 4- and 6-day-old females, respectively. The A cells in the 8-day-old females showed an accumulation of NSG. The mitochondrial population increases after adult emergence reaching a peak in the 4-day-old females, and then declines gradually in the subsequent age groups. The effect of sublethal dose of gamma radiation on the ultrastructure of the A cells was also investigated. Radiation damage is evident as early as four hours after irradiation with 10 kR. There is considerable swelling of the lysosomes and the membrane system in the A cells of irradiated insects. Synthetic activity of the A cells, based on the distribution of the endoplasmic reticulum, Golgi complex and mitochondria, as well as release of the NSG are apparently inhibited after irradiation. Radiation-induced damage becomes more conspicuous as post-irradiation interval increases. It is surmised that the damage to the A cells might have contributed at least in part, to the failure of yolk deposition in the irradiated insects.
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    Journal of Morphology 154 (1977), S. 133-145 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The junction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid-etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid-soluble than the peritubular matrix of primary dentine.
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  • 71
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    Journal of Morphology 154 (1977), S. 427-458 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Simultaneous cine and electromyographic records of freely feeding, unanesthetized golden hamsters show that their motion and muscular activity during mastication differ from those of albino rats (Weijs, '75). Rats show only propalinal motion while hamsters show lateral translation as well. The masticatory muscles of hamsters and rats are generally similar, but their molar dentitions differ. The interlocking molar cusps of hamsters restrict propalinal protrusion and retrusion when the molars are in occlusion; however, hamsters readily unlock occlusion by a twisting movement in the horizontal plane. Rats may perform propalinal movements even with the teeth in occlusion.In mastication the hamstery's jaw moves laterally as well as vertically and anteroposteriorly. Chewing orbits typically reverse after one to three orbits. Reversal begins at the start of the upstroke and involves a lateral shift in the opposite direction with the mouth closed.Electromyograms show that symmetric and asymmetric activities of closing protrusive and closing retrusive muscles produce a unilateral force couple on both sides. (This couple accompanies a midline closing stroke.) When the mouth is closed, unilateral activity of closing retrusors and closing protrusors also induces lateral translation. A bilateral force couple pits the retrusors of one side against the protrusors on the opposite side. Simultaneous with lateral excursion to the opposite side of midline and the action of these closing muscles, the anterior digastric and lateral pterygoid muscles of one side fire asymmetrically.The mandible moves downward coincidently with bilateral activity of the digastrics and lateral pterygoids. As the jaw opens further, activity differences of the lateral pterygoids accompany a shift of the mandible toward midline. At the end of the downstroke, all masticatory muscles studied are silent. The jaw returns to midline when the adductors fire asymmetrically at the start of closing.Trituration appears to coincide with an initial simple protrusion, which is subsequently accompanied by lateral translation. Different food types are reduced by distint chewing patterns with the differences clearest when the teeth are near occlusion. During gnawing the lateral pterygoids and digastrics fire longer, and the closing muscles fire less strongly. Chewing patterns in golden hamsters appear more generalized than those of rats; the differences may be directly associated with the ability of hamsters to store food in their cheek pouches.
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  • 72
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    Journal of Morphology 179 (1984), S. 229-242 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Wild-collected adults of Bombina orientalis are bright green dorsally and red to red-orange ventrally. As a prelude to an analysis of the differentiation of pigment cells in developing B. orientalis, we describe structural and chemical aspects of the fully differentiated pigment pattern of the “normal” adult.Structurally, differences between dorsal green and ventral red skin are summarized as follows: (1) Dorsal green skin contains a “typical” dermal chromatophore unit comprised of melanophores, iridophores, and xanthophores. Red skin contains predominantly carotenoid-containing xanthophores (erythrophores), and skin from black spot areas contains only melanophores. (2) In ventral red skin, there is also a thin layer of deep-lying iridophores that presumably are not involved in the observed color pattern. (3) Xanthophores of red and green skin are morphologically distinguishable from each other. Dorsal skin xanthophores contain both pterinosomes and carotenoid vesicles; ventral skin xanthophores contain only carotenoid vesicles. Carotenoid vesicles in dorsal xanthophores are much larger but less electron dense than comparable structures in ventral xanthophores.The presence of carotenes in ventral skin accounts for the bright red-orange color of the belly of this frog. Similar pigments are also present in green skin, but in smaller quantities and in conjunction with both colored (yellow) and colorless pteridines. From spectral data obtained for xanthophore pigments and structural data obtained from the size and arrangement of reflecting platelets in the iridophore layer, we attempt to explain the phenomenon of observed green color in B. orientalis.
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  • 73
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    Journal of Morphology 180 (1984) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 74
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    Journal of Morphology 180 (1984), S. 29-35 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study describes intercellular bridges in the ovaries of neonatal gerbils. Electron microscopy has revealed the presence of true intercellular bridges, connecting oogonia or oocytes, in ovaries of newborn gerbils. The cytoplasm of the intercellular channels is similar to that of the connected cells, with mitochondria, smooth and rough endoplasmic reticulum, and free ribosomes present. Lysosomes are also occasionally present in the intercellular bridges and they may be involved in early waves of oocyte atresia. An electrondense substance, 350-500 Å thick, is located immediately beneath the unit membrane of the intercellular bridges. Accumulation of electron-dense material increases the thickness of the walls of the intercellular bridges, supporting and maintaining the patency of the channels. It is suggested that the intercellular channels probably allow the interchange of nutrients, organelles, and possibly regulatory materials as well.
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    Journal of Morphology 180 (1984), S. 55-68 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparative study of the forelimbs of the semifossorial prairie dog, Cynomys gunnisoni, and the scansorial tree squirrel, Sciurus niger, was focused on the musculoskeletal design for digging in the former and climbing in the latter. Based on lever arm mechanics, it was expected that the forelimb of the prairie dog would show features appropriate to the production of relatively large forces and that of the fox squirrel to relatively great velocity. Force and lever arm measurements were made of select forelimb muscles at the shoulder, elbow, and wrist joints for a series of angles in both species. Contraction time and fatigue indexes were determined for the same forelimb muscles. Contrary to expectation, in the few cases in which significant (P 〈 .05) differences were found, the forces, lever arms, and torques (force times its lever arm) were greater in the smaller fox squirrel. The observed variation in the torques produced fits the demands on the forelimb during climbing and digging as estimated from films. Several forelimb muscles of the fox squirrel show significantly higher mean contraction times than do the homologous muscles of the prairie dog. There were no significant differences between the two species in the fatigability of the selected forelimb muscles, although the mean fatigue index was always higher (less fatigable muscle) in the prairie dog. Similarities in the forelimbs of these two sciurids suggest that only minor modifications may have been required of the ancestral forelimb in order for descendent forms to operate successfully as climbers and diggers.
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  • 76
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    Journal of Morphology 180 (1984), S. 105-124 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy of neurons of the stomatogastric nervous system of Ascheta domesticus was studied using heavy metal iontophoresis through cut nerve ends followed by silver intensification. Nineteen categories of neuron are described and compared with neurons known from the stomatogastric nervous system of other insects. Possible functions for the neurons are suggested. Motor neuron candidates are suggested for all parts of the gut served by the stomatogastric nervous system, and axons of sensory neurons of the anterior pharynx are located. There are four neuron types that cannot readily be assigned motor, sensory, or interneuron functions: large dorsal cells of the frontal ganglion; the two neurons of the nervus connectivus, and two categories of neurons in the median neurosecretory cell group of the pars intercerebralis, the axons of which are contained in the stomatogastric nerves.
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    Journal of Morphology 180 (1984), S. 159-169 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the pedicellar segment of the fly antenna there is a large campaniform sensillum. The central projection of the sensory cell (LCC) of this large campaniform sensillum is described from labeling with horseradish peroxidase (HRP) and cobalt. The LCC projects bilaterally to several regions of the brain and subesophageal and thoracic ganglia. The LCC processes in these termination areas were analyzed in relation to other neural processes, including the remaining antennal sensory and motor projection. This analysis was aided by combining HRP labeling with Golgi silver impregnation. Based on earlier findings and the present data we suggest that the LCC, with its various outputs in, e.g., antennal and leg motor centers, serves as a multifunctional sensory path involved in control functions necessary in flight.
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    Journal of Morphology 180 (1984) 
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  • 79
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    Journal of Morphology 180 (1984), S. 173-180 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the long starvation period (November to June) of the lizard (Varanus exanthematicus), pancreatic B cells undergo profound modification. The degeneration of β granules observed in electron microscopy appears correlated with the diminution of the immunoreactive insulin-like content of the pancreas. The analogy between the phenomena observed here and those reported in animals treated with alloxan is discussed.
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    Journal of Morphology 180 (1984), S. 195-211 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure and crystallography of the internal shell of the pulmonate gastropod slug Limax maximus were studied at the levels of light and scanning electron microscopy, revealing patterns of shell ontogeny and morphogenesis. The calcified portion of the slightly convex ovoid shell is composed of a single palisade layer of calcitic crystals. Numerous projections, 100 μm in width at the dorsal tip, are found on the dorsal surface of the shell and coincide with local nucleation sites of primordial calcium salt deposition onto the periostracum. With continued calcification these projections coalesce ventrally, forming the single crystalline shell layer. The organic portion of the shell includes the periostracum and an extensive PAS-staining conchiolin. In EDTA-etched preparations, conchiolin appears as a spongy network of fibers throughout the shell. Both horizontal and vertical components of the conchiolin are present, the former of variable thickness and occurring in an intercrystalline manner, the latter always occurring normal to the horizontal set. Macromorphogenic growth is characterized by three distinct temporal stages. Primary growth occurs radially from the umbonal region. Secondary growth is synonymous with shell thickening. Tertiary growth is characterized by both a lateral component, in which the shell extends beyond the primary growth boundaries, and a ventral component, in which the shell continues to grow in thickness. SEM of the ventral shell surface reveals a pattern of growth at the crystalmatrix interface. Proteinaceous fibers of the conchiolin occur unidirectionally in horizontal rows. Zones of incipient calcitic crystallization onto these hypostracal fiber bundles are contrasted by zones of increasing crystallization until the fibrous template (reduced hypostracum) is completely covered by crystals.
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    Journal of Morphology 180 (1984), S. 271-296 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microscopy shows that the pharyngeal lining of the larval lamprey Petromyzon marinus is a structurally complex epithelial system that can be separated into eight epithelial types: gill lamellar, gill interlamellar, goblet cell, protective, terminal (taste) bud, preciliated, ciliated in tracts, and ciliated in grooves. Furthermore, these epithelial types encompass at least sixteen different cell types based on ultrastructure and, in some cases, correlative histochemistry (PAS, Alcian blue). Common to nearly all the epithelial types are basal cells and intermediate cells. These two cell types are seen as undifferentiated. Among mature cells, structural specialization as proceeded in three directions: (1) elaboration of mitochondria, probably related to molecular transport (ion-uptake cells, chloride cells); (2) ciliogenesis (preciliated and ciliated cell types); and (3) production of mucous secretory granules (mucous-platelet cells, goblet cells, superficial protective cells, columnar mucous cells, “cobblestone” cells, and marginal and dark cells in the terminal buds). Many of the functions of the cell types relate to the process of suspension feeding in this animal.
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    Journal of Morphology 180 (1984), S. 243-252 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A small short muscle frequently acts across a joint in parallel with a vastly larger and longer muscle; therefore it should play a minimal role in the mechanical control of that joint. This study provides evidence suggesting that the small member of such a “parallel muscle combination” (PMC) may serve an important sensory feedback role. The spindle densities of large and small members of PMCs in man and the dog were determined and compared. Epaxial PMCs controlling canine intervertebral joints were dissected and tissue samples were embedded in paraffin, sectioned transversely to the muscles' long axis and, stained with hematoxylin-periodic acid-Schiff (PAS). Representative tissue sections were projected on to stereological grids and the percentage volume of spindles was determined. Data existing in the literature were used to ascertain spindle densities in human PMCs controlling joints in the cervico-occipital region and the extremities. The spindle density for each muscle in a group of PMCs controlling a particular motion was listed, and the mean spindle densities were determined for both the large and the small members of the group. Student's unpaired t test was used to determine the significance of the differences between mean spindle densities. Linear regression was calculated and the data were plotted graphically.In all PMCs examined, the spindle density of the small muscles was significantly higher than that of their large counterparts. It is therefore proposed that the small muscles of PMCs may function as “kinesiological monitors” generating important proprioceptive feedback to the central nervous system.
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    Journal of Morphology 181 (1984), S. 1-8 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The internal reproductive apparatus of female Platynotus punctatipennis is composed of the paired ovaries, paired lateral oviducts, common oviduct, spermatheca associated with its accessory gland, and a bursa copulatrix. The accessory (colleterial) glands are absent. The ovary is made up of a large number of telotrophic ovarioles which are covered by a double-layered peritoneal sheath. The terminal filament is separated from the germarium by the basement membrane of the latter and consists of a syncytial core surrounded by the peritoneal sheath. Nutritive cords are absent. The pedicel shows highly eosinophilic and PAS-positive secretion of obscure origin. The spermatheca reveals a number of interesting features. It is composed of a pair of sperm-storing tubules, enclosed in a very thin muscle layer. A winecup-like structure, provided with a thick coat of circular muscles, connects the spermathecal gland with thespermathecal duct. Four types of intimal linings occur in the spermatheca and its associated structures. The wine-cup-like connection and four types of intima are entirely new features observed. Histology of the various parts of the reproductive apparatus is described.
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    Journal of Morphology 181 (1984), S. 29-47 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation of somites, coelomic sacs, splanchnic mesoderm, fat bodies, circular system, gonads, and musculature in the embryo of the primitive moth, Neomicropteryx nipponensis Issiki, is described. The following paired somites are formed: the labral, antennal, intercalary, mandibular, maxillary, labial, three thoracic, and 11 abdominal. Small but distinct coelomic cavities appear in all these somites. Labral somites differentiate into the labral muscles, stomodaeal muscles, and dorsal dilator muscles of the pharynx. Antennal somites differentiate into the antennal muscles, aorta, and the ventral dilator muscles of the pharynx. Intercalary somites are short-lived, disintegrating to liberate many free cells into the yolk. The suboesophageal body is not formed. Mandibular somites differentiate into the mandibular flexor and extensor muscles. Maxillary and labial somites differentiate into the splanchnic mesoderm, fat bodies, and into muscles of the maxillolabial region. Three pairs of thoracic and ten pairs of abdominal somites split into the splanchric and somatic mesoderm. The 11th abdominal somites merge into the proctodaeal mesoderm, and differentiate into the musculature of the hindgut. The heart is formed by the fusion of the cardioblasts derived from the first thoracic to the tenth abdominal segment. The aorta arises from the antennal median mesoderm. Blood cells are derived from the median mesodermal cells of the maxillary to the tenth abdominal segment. Germ cells appear at the mediodorsal corner of each somite in the fifth abdominal segment. They become enclosed with a mesodermal sheath to form a pair of rudimentary gonads in this segment. Major muscles in the head, thorax, and abdomen of the fully grown embryo are described.
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    Journal of Morphology 181 (1984), S. 155-160 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The architectural and histochemical properties of the anatomically distinct compartments of the semitendinosus muscle (ST) of mice, rats, guinea pigs, and rabbits show that the ST is composed of two separate compartments aligned in series - a destal compartment (STd) and a proximal one (STp). The STp is further subdivided into a ventral head (STpv) and a dorsal head (STpd). The muscle fibers were arranged in parallel to the line of muscle pull within each compartment. The STd has the longest and the STpv the shortest fibers in all species. The physiological cross-sectional area and the estimated tetanic tension was greatest in the STd. Based on the staining pattern for myosin ATPase (alkaline preincubation) and an oxidative indicator (NADH or SDH), the STpv has the highest percentage of slow-oxidative (SO) or SO plus fast-oxidative-glycolytic (FOG) fibers of any portion of the muscle. The differences in fiber-type distributions and architectural designs of the separate compartments suggest a specialization of function of the individual compartments.
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    Journal of Morphology 181 (1984), S. 97-131 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The three-dimensional structure of the organ of Bellonci in the marine amphipod Gammarus setosus and the relationship between its sensory cells and concretion are described using light, transmission, and scanning electron microscopy, with chemical treatment for cell lysis, calcium chelation, glycogen staining, and lanthanum labelling. The organ is encapsulated and has three units called fuselli. Each is enclosed by two fusellar cells which generate and release calcium granule strands into the cores of the fusellar concretions, which are united in the center of the organ. The surface of each fusellus is traversed by spiral dendrites entering dorsally and ending ventrally. The spiral dendrites arise from sensory neurons contained in a palm-shaped ganglion in the center of the capsule, beyond which they are twisted like a rope before reaching the concretion. The spiral dendrites are linked in pairs by gap and tight junctions and each gives origin to two pairs of 9+0 sensory cilia 30 μm apart. The ciliary distal segments give rise to long tubules which are in contact with the calcium granule strands. The ciliary proximal segments are expanded by many long mitochondria which interdigitate with the branched striated ciliary rootlets. The concretion is suspended in the capsule cavity by axons originating from four neurons of a remote mechanoreceptor. The structure of the organ suggests that it is a sensory organ involved in the reception and integration of a variety of stimuli.
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    Notes: The fine structure of the kidney and the bladder of the bullfrog (Rana catesbeiana), the bullfrog tadpole, and the mudpuppy (Necturus maculosus) were studied with special attention to the innervation of renal tubule cells and bladder epithelial cells. In the bullfrog kidney, nerve terminals and varicosities were frequently associated with the tubule cells, apparently in an increasing order from the proximal tubule to the connecting tubule. Although these terminals and varicosities did not directly contact the tubular cell membrane, an aggregation of synaptic vesicles on the side facing the tubule was considered as morphological evidence that neurotransmitter can be released here and can affect the transport activity of the tubule cells. The association of nerve varicosities with canaliculi cells in the connecting tubule was also demonstrated. In the bullfrog tadpoles, renal tubule cells were occasionally innervated. In the mudpuppy, renal tubule cells were only poorly innervated. The epithelium of the bullfrog bladder was commonly innervated. Nerve terminals with synaptic vesicles were located very near basal cells and even contacted them directly on rare occasions. In the mudpuppy, the innervation of the bladder epithelium was observed infrequently. The bullfrog tadpoles did not possess an apparent bladder. In all materials studied, renal arterioles and bladder smooth muscle cells were innervated.
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  • 90
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    Journal of Morphology 40 (1925), S. 261-297 
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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 parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V-shaped leptotene threads are polarized with their apices embedded in one plasmosome-like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring-shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.
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    Journal of Morphology 41 (1926), S. 441-546 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryological study of bullfrog tadpoles collected from various parts of the United States has shown the existence of local races which differ markedly in regard to the time of occurrence and character of the developmental processes involved in the formation of the definitive testis of the male individuals. Those races in which the gonads of the two sexes are easily distinguished in early larval stages are called differentiated. Other local races show a peculiar gonadic development chiefly affecting the males, the definitive testis sometimes not appearing until near the end of the second year of larval life. Such races are called undifferentiated, because the morphological features of the definitive testes are not established until late. The larvae first develop a peculiar gonad (progonad) which later degenerates and is replaced by the definitive testis. All male animals of the undifferentiated strains exhibit the gonad cycle.The progonad varies among the local frog races in regard to the length of persistence and degree of differentiation attained before undergoing degeneration. Its germ cells may exhibit a typical male maturation cycle ending in degeneration, or the cells may differentiate along both male and female lines or remain sexually neutral.The development and differentiation of the progonad in the various races are described and a detailed account given of the origin of the definitive testis. The problems of sex differentiation and continuity of the Keimbahn in anurans are discussed.
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    Notes: The primordial germ cells of urodeles and anurans can occupy comparable positions in the embryo only in very early stages of development, if at all. When first recognizable as reproductive elements, their situation in the two amphibian orders is quite strikingly different.The germ cells first become recognizable in urodeles in the medial edge of the lateral mesoderm; there is no evidence that their position previous to this time is other than mesodermal. In the anura they are entodermal in association during early development; they are finally separated from the dorsal portion of the roof of the archenteron to form a single axial germ-cell cord. No amphibian species studied showed a mode of origin different from that characteristic of its order.The so-called migration of the amphibian germ cells to their definitive situation is interpreted as the result of growth shiftings of related parts. Germ cells do not migrate independently through the tissues. Aberrant or ectopic cells for the most part result from failures or faulty correlations of growth processes. Certain aberrant cells of the caudal portion of the body in urodeles indicate the inclusion of sex elements in the ventral as well as in the lateral mesoderm.
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    Notes: The musculature of the ophidian head is a fairly complex structure, due to the specialization of the skull and the peculiar movements and motions made possible by the high degree of streptostylism.This musculature has been derived from the lacertilian type by a splitting and a shifting of the original elemental muscle masses of this group. Most of the muscles are clearly homologous with those of the Lacertilia. Some cannot be homologized by a study of the mature forms.The greatest differences lie in the separation of the muscle masses in the ophidia, as compared with the undivided masses in the Lacertilia. Since the jaw movements of the Lacertilia are rather simple, there is no need for any subdivision or splitting of the jaw muscles, but with the complex movements of the ophidia this becomes necessary.A few of the ophidian muscles appear to be neomorphs, as no key to their origin could be determined by a comparison with lacertilians.
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    Journal of Morphology 41 (1926) 
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    Journal of Morphology 41 (1926), S. 333-345 
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    Notes: In a leech infesting the Alaskan codfish germinal masses in the ovary proliferate secondary groups, comprising about forty cells in which a follicle and central supporting cell early differentiate. Active division results in approximately 500 cells which apparently develop ductules extending to a point on the surface of the egg. Granules of unknown origin then appear in each nurse cell, and are drawn down the ductules into the egg which can now be distinguished. Reasons are given for the belief that the nutritive material is drained from the nurse cells by amoeboid activity of the egg. In early stages the nutritive mateiral forms a loose reticulum which gradually becomes transformed into a more extensive network, persisting until the maturation divisions. In this latest period the follicle and nurse cells, which become shrunken as the ovum enlarges, usually are stripped off and soon disintegrate.
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    Journal of Morphology 41 (1926), S. 547-579 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pelvic fins of the ancestors of the Chondrosteoidei possessed a metameric musculature and their skeleton consisted of a large number of metamerically arranged cartilaginous fin-rays, to which were attached osseous lepidotrichia. Evolution has involved the concrescence of separate elements to form the basal cartilage, the proximal end of which forms the girdle of the fin; the loss of a number of the fin-rays, and the atrophy of distal elements of the rays. The adult Chondrosteoidei have retained the primitive fin structure which characterized the elasmobranchs of the Palaeozoic period and which has disappeared in recent forms.
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    Journal of Morphology 42 (1926), S. 143-195 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: On the basis of experimental study and observations on the morphology of the legs of spiders, P. Friedrich described a cutting device within the trochanter which would sever that appendage from the body when the leg was stimulated by injury.A reinvestigation of the problem yielded entirely contrary results. Experiments calculated to induce spontaneous amputation through an automatic reflex in the leg were negative on scorpions, harvestmen, and more than a dozen species of spiders. A detailed morphological study of the skeleton and musculature of the arachnid leg showed that no autotomizing device exists, either in the skeleton or in the arrangement of muscles (as is usually supposed). In all species studied, except the scorpion, severance of the leg from the body occurs most readily at some given point. The point at which severance readily occurs is directly correlated with a definite structural weakness in the skeleton and musculature. The spider itself removes an injured leg by grasping the stump with its mouth-parts. No such injured stump falls off spontaneously or without the application of tension. Scorpions do not autotomize appendages under any stimulation, nor do they show any anatomical weakness in the leg skeleton or musculature.Autotomy as an automatic reflex does not exist in the Arachnida.
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sixteen species of the genus Scyllium are here considered and arranged in groups according to the accessory structures present on the claspers as follows:1Canicula, sufflans, ventriosum.2Catulus, stellare, capense, variegatum (var. pantherinus), umbratile.3Burgerii, hispida, bivium, anale, natalense, edwardsii.4Marmoratum, laticeps.The structure of the wall of the oviduct and vagina is demonstrated, and it is shown that the epithelium of both is at first columnar, then ciliated in immature specimens; at maturity that of the vagina further undergoes by transitions a change to stratified. The walls are highly vascular, but contain no special glands.
    Additional Material: 14 Ill.
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  • 99
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amoeba responds to a mechanical shock by a cessation of movement which occurs shortly after the application of the stimulus. The length of the reaction time, the period intervening between application of stimulus and the response, varies inversely with the magnitude of the shock. After stopping Amoeba remains quiescent for a short time, and the length of this period of quiescence varies directly with the magnitude of the shock. A certain amount of time must elapse after a reaction before another can be obtained; during this time the animal reverts to the physiological state which existed prior to the first shock.Partial recovery from the effects of a shock is manifested by a reaction time that is longer than after complete recovery, and a period of quiescence which is shorter. A shock which in itself is too slight to cause a cessation of movement may result in the lack of a response to a heavier one which follows immediately after it, although under other conditions the second shock would have called forth a reaction. If the second shock, however, is made sufficiently heavy, it will bring about a response, despite the effects of the first. This is what would be expected if the reactions take place in accordance with the Weber-Foechner law.
    Additional Material: 4 Tab.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 523-560 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The different kinds of scales characteristic of the adult sturgeon are described and the facts of ontogenesis which throw light on the history of these structures are presented.The scales of Acipenser are exclusively mesenchymatous and therefore are not morphologically comparable with the placoid scales of elasmobranchs. Salensky ('80) drew erroneous conclusions as a result of failure to study the earlier stages of ontogenesis. Goodrich ('03) has correctly described the ontogenesis of the lepidotrichia.The original form of ganoid scale was that of an elongated rhomb with a longitudinal crest on its external surface. The various forms of scales of the adult sturgeon have been produced by the differentiation of such a scale by change in size, shape, and the fusion of the different elements.The conclusions are extended to the entire family of Acipenseridae.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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