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  • Life and Medical Sciences  (10,799)
  • ASTROPHYSICS  (7,632)
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  • 1925-1929  (172)
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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
    Electronic Resource
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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
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    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
    Electronic Resource
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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
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 521-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers - exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle.Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 1-20 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound - all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
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  • 12
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 117-125 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the early cleavage stages of Ascaris the homologous chromosomes are of unequal length. Measurements show that these homologues fall into two sharply defined groups suggesting their biparental origin. The shorter are considered to have come from the male.As the age of the embryo increases, these differences between the chromosome mates tend to become less, and it is suggested that at some later period in the history of the animal this difference will entirely disappear in response to the effect of continued existence in a common environment. The length of the chromosomes is very slightly shortened during the early cleavage divisions, while the area of the equatorial cross-section of the cells becomes enormously reduced.
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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 313-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour-moth and bee-moth pupae (Lepidoptera), although all are of the same general U-shaped type. There are strong indications of a specific difference in the curves of the blow-fly pupae. The flour-moth pupae curves differ slightly from those of the bee-moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 363-372 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The history of investigations on the contractile vacuole is reviewed briefly and brought up to date.The study of the contractile vacuole in Amoeba proteus is considered from standpoints of origin, structure, behavior, and function. The results are obtained from a prolonged study of normal organisms and from their reactions when introduced into conductivity water.The origin of vacuoles is studied by means of dark-field illumination which reveals the vacuole to be formed from a fusion and coalescence of extremely minute droplets.The retaining ‘wall’ of the contractile vacuole is not a permanent structure, but is in the nature of a condensation membrane, totally disappearing with each contraction.The loci of the contractile vacuoles are not permanent, but vacuoles are formed more or less at random. It is unlikely that they are supported in gelated areas, for amoebae with a dozen vacuoles are quite active and there is no interference with amoeboid movement.Conductivity water increases the size, number, and rate of contraction of contractile vacuoles, which suggests that they may function in maintaining an osmotic gradient as well as in the elimination of metabolic waste.
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  • 15
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 467-514 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The eggs of Corella develop in the atrial chamber of the parent at a pH below that of normal sea-water (pH 7.4 ±). When removed to normal sea-water in early stages and under certain other experimental conditions, larval development is more or less inhibited, the tail being most inhibited, the dorsal region somewhat less. The free larval stage may be eliminated and later development and metamorphosis may proceed normally to an advanced stage in the chorion and give rise to normal ascidians. The region most inhibited are, in general, those which possess the highest reducing power, as indicated by KMnO4. Experiments made in the attempt to control development all agree in indicating that the early stages are adjusted to a certain CO2 concentration approximately that of the atrial chamber and presumably near that of the body. Solutions of the same pH may or may not inhibit development according to their CO2 content.The tail, the region of highest reducing power in the embryo during its development, is most inhibited; the dorsal region, the next most rapidly reducing region, is next in degree of inhibition. All differences in reducing power disappear when, or soon after, the animals are killed by other agents before treatment with KMnO4.
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  • 16
    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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  • 17
    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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  • 18
    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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  • 19
    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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  • 20
    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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  • 21
    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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  • 22
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    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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  • 23
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    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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  • 24
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    Journal of Morphology 45 (1928) 
    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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  • 25
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amoeba proteus was raised in a modified and diluted Ringer solution. When the pH of this culture medium became less than 6.0, the normal activities of the amoebae were interfered with; and when a still lower pH was attained, the amoebae died off. The same was true when the pH became greater than 8.0. At neutrality the activities were subnormal, very dark, and rounded. The rate of locomotion of amoebae raised in solutions with a pH less than 7.0 showed a maximum rate of locomotion at pH 6.6, which decreased as the pH changed in either direction, dropping to a very low rate at pH 7.0 and above and also below 6.0. For amoebae raised at a pH above 7.0 the rate was maximum at pH 7.6 and decreased as the pH changed in either direction; it was low at pH 7.0 and below and also above 8.0.On increasing the external osmotic pressure of the medium it was found that the effects caused varied somewhat with the hydrogen-ion concentration. Small increases in osmotic pressure decreased the rate from the normal at pH 6.0 and 8.0, increased it at pH 6.6 and 7.6, and did not affect it at pH 7.0. Osmotic pressures above that produced by M/20 lactose caused locomotion to cease in a short time at all pH values.
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  • 26
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    Journal of Morphology 45 (1928), S. 209-231 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The highly specialized cranial musculature of the toadfish is characterized by the following features: 1Absence of intermandibularis and branchiomandibularis muscles.2Presence of levator premaxillaris muscle.3Very large branchial chamber, the outer wall of which is formed by seven branchiostegal rays connected by a strong fascia provided with muscles (oblique levators and adductors).4Highly developed masticator muscles (adductor mandibularis and pterygoids).5The rectus abdominis, sternohyoid, and hyohyoid muscles are attached by a median aponeurosis to the hyoid and basibranchial elements and directly to the hypobranchial cartilages; this muscle complex depresses the buccal floor in opposition to the geniohyoid.6The pelvic fins are in the jugular position.7Two narrow muscles connect the cleithrum with the fourth ceratobranchial.8The cranial musculature is obviously adapted to a carnivorous habit and particularly for increasing respiratory capacity under asphyxial conditions.
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  • 27
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    Journal of Morphology 45 (1928), S. 293-398 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Blindfolded persons walk, run, swim, row, and drive automobiles in clock-spring spiral paths of greater or less regularity when attempting a straightaway. The spirals turn either right or left in one and the same individual, and may do so even in one experiment. But either right or left turns predominate in the great majority of individuals, often to a high degree. The paths show marked individuality, and there is some ground for thinking there exists a correlation between temperamental differences and general character of path.The mechanism which produces the spiral path is not located in the locomotor organs, but in the central nervous system and is probably identical essentially with the spiral mechanism in other motile organisms, all of which move in spiral paths when there are no guiding senses to direct the path. The clock-spring spiral in man is interpreted as the expression in two dimensions of space of a helical spiral mechanism which seems to exist in all motile organisms moving in three dimensions of space and in amebas which move in two dimensions. In a large number of lower organisms the number of body lengths per spiral turn is almost constant, being about 4.5. The smallest regular swimming spirals in man are very close to this value, but the smallest regular walking spirals are somewhat larger. The fundamental spiral mechanism seems to be of molecular dimensions, and there seems to exist a demonstrable locomotor bilateral asymmetry in very nearly, if not quite, all organisms.
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  • 28
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    Journal of Morphology 45 (1928), S. 473-503 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A detailed study has been made of the anatomy of one of the fingernail shells, and preliminary observations on the life-history have been carried out. In its general organization Sphaerium notatum is very similar to the larger fresh-water lamellibranchs. A gastric shield, crystalline style, and style sac, very similar to those found in the stomach and intestine of Lampsilis, are present. A pair of slender muscles extending from the dorsal side of the body into the gills, and evidently not previously described, have been found. The nervous system consists of the typical three pairs of lamellibranchiate ganglia, with their connectives, accessory ganglia, and nerve fibers. Particular study was given to the statocysts and osphradia, and attention is called to the fact that the function commonly ascribed to the osphradia is incompatible with their position in the roof of the cloacal chamber.S. notatum, like all the Sphaeriidae, is hermaphroditic and viviparous. The gonads are paired racemose glands lying behind and below the stomach. The sperm-producing follicles form the anterior portion of each gonad and are somewhat smaller and more numerous than the ova-producing follicles which form the posterior portion. The young pass through the early stages of development in brood pouches in the gills and are expelled as relatively enormous individuals.Preliminary observations on the life-history indicate that reproduction reaches its height in the summer and that fertilization probably takes place during the late summer and fall.
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  • 29
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    Journal of Morphology 45 (1928), S. 579-597 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When Menidia eggs are fertilized with Prionotus sperm, the Prionotus chromosomes react in the Menidia cytoplasmic medium just as they do in the cytoplasm of Fundulus eggs. There is lagging, non-disjunction, and elimination of chromosomes during the early cell divisions. The mitotic behavior of the Prionotus sperm in the Menidia egg also resembles the behavior of the sperm of Ctenolabrus in the same medium. This behavior which was expected from what was known concerning the mitotic behavior of the reciprocal crosses between Menidia and Fundulus and between Ctenolabrus and Prionotus and other intercrosses between the members of these two groups is regarded as a function of the physical state of the egg cytoplasm during the division phase of mitosis. This physical character forms the earliest differential factor in the development of these hybrids and shows no correlation with the width of the cross.A comparison of nine teleost crosses, in which both the development and the early mitotic behavior are known, with a rough numerical estimate of the width of the cross brought out the fact that development is most successful in crosses between nearly related species if mitosis is normal and in distantly related crosses if mitosis is abnormal. This indicates that nuclear relationship is also a factor in the development of hybrids.
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  • 30
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Virulent hay-infusion cultures of Bacillus pyocyaneus are toxic to pure-line races of three species of paramecia, but these races may acquire a tolerance for this toxic agent. Races with acquired tolerance have been grown for long periods of time in toxic, pure cultures of B. pyocyaneus by means of the daily-isolation culture method, and here the average division rate is as high as, or higher than, in the chance-mixed bacterial cultures in which these protozoa are usually maintained in the laboratory. The tolerance is lost, however, when the paramecia are removed from the toxic cultures and grown for a number of generations in cultures of non-toxic bacteria.The toxic agent that is lethal to paramecía is probably the soluble toxin of B. pyocyaneus. The investigation shows that the agent is soluble and either thermolabile or volatile. It also shows that all deleterious substances, other than the soluble toxin, known to be produced in cultures of this bacillus, are non-lethal to paramecia.Hay-infusion cultures of Bacillus enteritidis were lethal to paramecia. All attempts to develop tolerance in paramecia for the toxic agent in these cultures failed.Under the experimental conditions that prevailed, diphtheria toxin was found to have no appreciable effect upon the division rate or death rate in three species of paramecia.
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  • 31
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    Journal of Morphology 118 (1966), S. 549-563 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Visualization of stainable material in the neural lobe of the rat provided the most reliable index of the age at which secretory activity can first be recognized, though preceded by both hypothalamic synthesis and axonal transportation. A problem of interpretation was encountered in the neural lobes of fetal and infant animals, due to different staining responses obtained during this age period, to the two methods of staining employed; chrome alum hematoxylin-phloxin and aldehyde fuchsin after oxidation by either acidified potassium permanganate or performic acid. With aldehyde fuchsin the material of the neural lobe is stainable selectively from the eighteenth day of fetal life to adulthood. With hematoxylin phloxine the first staining response also occurred in the posterior lobe but much later, at the end of the first postnatal week.The staining situation in the pars neuralis has its counterpart in the differentiating hypothalamic nuclei; complicated by the differentiation of the supraoptic nuclei some days in advance of the paraventricular nuclei. After aldehyde fuchsin staining, evidences of neurosecretory activity were present in the perikarya of the supraoptic nuclei at birth, but mature neurons were rarely seen in the paraventricularis until at least 24 hours later. Nuclei of fetal hypothalami were not studied, but the demonstration of stainable material in the fetal neural lobes constitutes circumstantial evidence of functional competence of some neurons of either one or both types of nucleus, most likely the supraoptic.
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  • 32
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    Journal of Morphology 119 (1966), S. 1-5 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Small crenulated erythrocytes appear in the circulation of Rana pipiens during metamorphosis, increases in number as metamorphosis proceeds and gradually lose their wrinkled appearance. At the end of metamorphosis the entire red cell population has been replaced by these new cells. Thyroxine induces the premature appearance of these new cells in young tadpoles.
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  • 33
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    Journal of Morphology 119 (1966), S. 39-50 
    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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  • 34
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution and morphology of the argentaffin cell population within the stomach of the albino rat has been investigated histologically. The argentaffin cell's situation is restricted to and evenly distributed over the antrum, lying usually in the basal third of the mucosa among mucous cells. A band of mucosa, less than a millimeter wide, containing argentaffin cells, extends from the antrum and encircles the stomach just caudal to the forestomach. The argentaffin cell population is found in less than three-tenths of the total stomach by weight, a point for consideration in serotonin assay.
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  • 35
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    Journal of Morphology 119 (1966) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 36
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    Journal of Morphology 119 (1966), S. 89-100 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report presents a study of cataracts seen in a random-bred strain of Swiss mice with Balb/c mice used as a control group. The embryonic development, and histological and slit lamp observations of the lenses in the two groups of animals are contrasted.The cataract is dominant in its inheritance (Tissot, '62). It appears either unilaterally or bilaterally as a dense white opacity in the lens substance. The earliest sign of abnormal formation occurs at 14 days of embryonic development. This is associated with a defect in the primary lens fibers formation. Progressive degeneration of these fibers occurs until they are reduced to a mass of cellular debris seen at the last day of gestation. The secondary fibers are also laid down in an abnormal manner. The normal lamellar arrangement of the secondary fibers is not seen in cataractous lenses.The abnormal lens fiber development leads to progressive vacuolization.The mature cataract seen in the adult is filled with many vacuoles, the largest ones occurring at the equatorial region. The nuclear region consists of a clumpy eosinophilic mass with scattered calcified areas. The rate of growth of the secondary fibers is different from that of the normal group. Most of the mature cataracts in the adult contain a vascularized epithelium.There are three possible areas of primary involvement which may lead to the development of the cataract. This are: (1) A defect in the development of the primary lens fibers; (2) A defect in the development of the secondary lens fibers; (3) An abnormal lens epithelium which may interfere with nutrition of the lens and thus initiate cataract formation.
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  • 37
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spiroid orientation of the circumferential heart wall muscles is described for Centruroides sculpturatus Ewing. This muscle arrangement accounts for differences in ostial position when the heart of this species is compared to that of Uroctonus mordax Thorell. Other differences, such as number of lateral arteries present, cannot be explained on the basis of circumferential muscle orientation.The histology of the heart and associated vessels, but not the supraneural vessel, was found to be similar in both species. The lateral, posterior, communicating and sternal arteries all possess a muscularis composed of irregularly spaced, apparently branched, striated muscle fibers. External to this is a covering of connective tissue. The lumina of these arteries, the aorta, and the supraneural vessel are lined with a homogeneous, PAS-positive membrane. This membrane is also seen in blood vessels which penetrate the nervous system. It was not observed in vessels accompanying major nerves.Findings are compared to those of other authors. Differences in the structure of the hearts of these two species are discussed in relation to the microanatomy of other arachnid hearts.
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  • 38
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    Journal of Morphology 119 (1966), S. 233-240 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development and replacement of teeth in the frog Rana temporaria is analyzed by dividing the life cycle of the tooth into a number of stages. These stages are identified by the examination of alizarin whole mounts. The dentition in this species is fairly complete and the percentage of functional loci is approximately 74. The teeth in alternate loci are usually at about the same stage in development. The low percentage of non-functional loci is accounted for by the retention of functional teeth over a large fraction of the total life cycle time and the relatively rapid ankylosis of replacement teeth. It is suggested that tooth replacement is essentially a process which involves teeth in alternate loci and that the replacement waves (which connect alternate loci) run parallel to the longitudinal axis of the jaw and are of infinite length. This basic pattern is obscured by many breaks which occur in the replacement waves. The presence of such breaks may be accounted for by variations in the time intervals between the successive stimuli which initiate the Zahnreihen, or simply by the acceleration or deceleration of the development of teeth in one or more loci.
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  • 39
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The major features of the morphogenesis of the muscles of the hindlimb, exclusive of the foot, are described and illustrated for the frog, Rana pipiens The description is carried through the stage XII larva, in which stage most of the muscles of the adult limb are present in essentially the definitive condition. As is true of other vertebrates which have been studied, the muscles of the hindlimb develop from two major premuscular masses. One of these lies along the dorsolateral margin of the limb and the other along the ventro-medial margin. Each of the two masses is subsequently divided into smaller and smaller subdivisions as the different muscle groups and the individual muscles are differentiated. In general, the more proximally located muscles differentiate before those which are located more distally and those of the dorso-lateral mass before those of the ventro-medial mass.The following muscles of the thigh, shank and tarsus develop from the dorsolateral mass: ileo-fibularis, glutaeus magnus, cruralis, ileo-femoralis, iliacus externus, iliacus internus, tensor fasciae latae, pectineus, adductor longus, peroneus, tibialis anticus brevis, tibialis anticus longus, extensor cruris brevis, tarsalis anticus, extensor digitorum communis longus and abductor brevis dorsalis. The following develop from the ventro-medial mass: compressor cloacae, circumflexor arteriae, pyriformis, semimembranosus, gemellus, gracilis major, gracilis minor, semitendinosus, adductor magnus, obturator internus, obturator externus, quadratus femoris, sartorius, plantaris longus, tibialis posticus, tarsalis posticus, plantaris profundus, intertarsalis and flexor digitorum brevis superficialis.
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  • 40
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tissues of White Leghorn embryos of stages 17-45 and chicks of one day, two days, and three weeks of age were frozen, sectioned in a cryostat and, where appropriate, were fixed in cold calcium formol. Acid phosphatase, non-specific esterase, adenosine triphosphatase, 5-nucleotidase, non-specific glycerophosphatase, nucleotidediphosphatase, and glucose-6-phosphatase were localized in these tissues. Ribonucleic acid, acid mucopolysaccharides, triglycerides, and neutral fats were localized in tissues fixed with FAA and embedded in paraffin.Positive acid phosphatase reactions were obtained in the epithelium of the trachea and esophagus at all stages of development. 5-nucleotidase was found in the muscularis mucosae of the esophagus at all stages. Non-specific esterase appeared with histodifferentiation of the esophageal epithelium. Ribonucleic acid was localized in the basal regions of the epithelium.Mucous glands of the esophagus are rich in ribonucleic acid and acid phosphatase at all stages of development. With histodifferentiation and the onset of secretion of sulfated acid mucopolysaccharides, the glands and their ducts become highly reactive for adenosine triphosphatase and nucleotide-diphosphatase, indicating a role of these enzymes in secretion.
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  • 41
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    Journal of Morphology 119 (1966), S. 277-281 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Testicular structure in bisexual teiid lizards (Cnemidophorus and Ameiva) is apparently unique among vertebrates in having a circumtesticular subtunic band of Leydig (interstitial) cells, that varies in species of Cnemidophorus from 1.2 to 42.1 cells in thickness (transverse cross-section), between the outer tunic (tunica albuginea) and the seminiferous tubules. The regression on body size, ontogenetic change, seasonal periodicity, and other aspects of structure and function of this subtunic Leydig cell structure are discussed.
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  • 42
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The egg chamber of Drosophila melanogaster consists of 16 interconnected cells surrounded by a monolayer of follicle cells. Each 16 cell cluster (from which the oocyte and 15 nurse cells differentiate) arises within the germarial region of an ovariole. To study the ultrastructure of the early stages in the formation and differentiation of egg chambers, a three dimensional reconstruction was made from serial thin sections through a germarium from a 24-hour old, virgin female. The germarium was found to be subdivided into three regions: (1) The mitotically active area where clusters of 16 cells originate from a series of cystocyte divisions, (2) the region where these cells interact with mesodermal cells, and (3) the region where the germarial cyst is transformed into the first egg chamber in the vitellarium. Since cystocytes were found to decrease in size with each division, the possibility exists that cell size may determine when the divisions cease. Models are presented which mimic with varying degrees of success the developmental changes the germarial cells undergo with time. Hypothesis are developed to explain why stem line oogonia are restricted to the anterior portion of the germarium, why mesodermal cells first interact with cystocytes in region 2, and why the oocyte is oriented posteriorly. The nuclear differentiations of the component cells of the chamber are described and correlated with observed differences in radiosensitivity. Symbionts were observed in the germaria of several strains of Drosophila, and the bearing of these findings upon nutritional studies is discussed.
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  • 43
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The physiology and fine structure of the vibration receptor of the spider (Achaearanea tepidariorum) was studied throughout the process of molting. The physiological studies showed that there is no dramatic change in the receptor's vibration sensitivity as the time of ecdysis approaches. Only a gradual loss of sensitivity can be detected on a statistical basis using large numbers of spiders. The fine structural studies suggest that the connection between the sensory neurone and the receptor within the old cuticle remains intact up to the time that the cuticle is shed.
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  • 44
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Since the rabbit's eye more nearly resembles the human eye than any other mammal used in experimental investigations, a detailed study of its ciliary arteries has been made. A closely timed series of embryos injected through the living umbilical vein and rendered transparent show, in thick sections, silhouetted vessels in perspective. Heretofore the ciliary arteries have been studied from their first identification until they have reached the primitive choriocapillaris, but no farther. This study shows their complete history including their relation to the circulus arteriosus iridis major and to the pupillary membrane. Our special concern has been ferreting out the mode of migration of the components of the definitive arteries. New findings include: (1) an arteriovenous plexus which mediates the transference from vessels anastomotic with it to other such vessels; (2) functionally different segments of the primitive ciliary arteries; (3) different arterial and venous plexuses which play roles in embryonic development; (4) discovery of the realignment of the choriocapillaris into vertical vessel meshes with transverse anastomoses between them, each of which have different fates; (5) the mode of development of the circulus arteriosus iridis major; (6) a crown of venous vessels looping around the iris margin; and (7) a special arterial supply for the ciliary processes.
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  • 45
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The phylogenetic development of neuroglia (astrocytes, oligodendrocytes) was investigated in homologous cortical and subcortical forebrain regions of selected vertebrates. Microglia were not considered in the current study.Four to seven brains from each species were used. Scharenberg's modification for astroglia of del Rio Hortega's silver carbonate technique was used. The analysis of neuroglia cells was based on (1) the characteristic cellular morphology found in each species, (2) a comparison of the selected regions in each animal, (3) the interrelationships of astrocytes and their relations to neurons, blood vessels, and oligodendrocytes.The predominant type of neuroglia found in the fish, frog, and lizard was the ependymal cell; however, non-ependymal glial cells were also present. The bird represented a transitional phylogenetic stage from a predominance of ependymal glial to a predominance of non-ependymal glia. A progressive increase in the morphological relationships of glial cell bodies and processes to neurons was found with ascension of the phylogenetic scale from fish through primate.Interrelations were observed between adjacent astrocytic processes and cell bodies, and between astrocytes and oligodendrocytes. The processes of adjacent glial cells also appeared to show an increase in thickness at the point of approximation. A variety of astrocytes were observed ranging from small, round-oval shaped cells to large polygonal or stellate forms. Variations in the number of astrocytic processes, their thickness, and degree of secondary branching were described, and their possible functional significance was discussed.
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  • 46
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gland cells of the gastrodermis of Hydra when isolated from the epidermis are capable of dedifferentiating into interstitial cells. Under proper environmental conditions these interstitial cells are capable of undergoing meiotic divisions and forming normal gametes. This dedifferentiation and redifferentiation sequence has been studied at the level of the light and electron microscope. It is concluded that in Hydra there is no specific germinal cell line determined during embryogeny, and that a somatic cell under proper environmental conditions can be induced to undergo meiosis.
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  • 47
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rectal epithelium of Calliphora is made up of three quite distinct cell types: rectal, cortical and junctional cells.The thin wall of the rectal pouch is made up of rectal cells which are relatively simple and unspecialized; their general structure does not suggest any direct participation in ion transport.A function of ion and water transport can probably be ascribed to the cortical cells, which are arranged in the form of four cones which project into the rectal lumen. The cavity of each cone is filled up with tracheae, nerve and neurosecretory terminals, and connective tissue to form medulla. The medulla and cortex are separated from each other by deeply staining bridges or trabeculae to form an infundibular space. The most conspicuous feature of the cortex is the presence of an extensive intercellular sinus formed by complex infoldings of the lateral plasma-membranes. It is postulated that fluid, which is absorbed from the rectal lumen, is transported into the intercellular sinus and finally reaches the haemolymph via the infundibular space. The actual site of ion transport is probably the stacks of lateral plasma-membrane which are closely associated with mitochondria.The junctional cells, which are packed with microtubules, form a collar around the base of the papillae at the point of their insertion into the rectal wall.It is suggested that the neurosecretory terminals present in the medulla might release a hormone which controls rate of ion and water reabsorption by the papillae cells.
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  • 48
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The long, filamentous antennal flagellum of Carausius morosus has on it three types of sense organs (1) tactile hairs, (2) thick-walled chemoreceptors and (3) thin-walled chemoreceptors. Tactile hairs and thick-walled chemoreceptors are present on all of the 40 or more flagellar subsegments while thin-walled chemoreceptors are limited to about one-third of them. Thin-walled chemoreceptors are present on subsegments nine and ten, one of the subsegments between 15 and 20 and from approximately the thirtieth subsegment to the distal end of the antenna. A description of each of these sense organs is given. No coeloconic or campaniform sense organs were found.
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  • 49
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoarchitecture of the choroid plexus of the third ventricle and the paraphysis was investigated in some lower vertebrates to compare the histologic characteristics of these organs. Both epithelia are similar in appearance in the same class. Minor microscopic variations exist in the different classes of vertebrates, but do not provide a fundamental distinction between the two organs. The epithelia, moreover, have similar staining properties, contain mucicarmine- and PAS-reactive materials, and are derived from a common neuroepithelium. Tubules are identified in the choroid plexus and in the paraphysis; all are similarly formed by simple folding of epithelium on the surface into the stroma. The paraphyses in all vertebrates studied contain villi similar to those seen in the choroid plexus. Cilia are identified in both choroidal and paraphyseal epithelia, and are not an indication of degree of epithelial differentiation. Many types of epithelium are noted in both organs during histologic differentiation as well as in the mature stage. Functionally, the choroid plexus is active in both secretion and absorption. Accumulation of particulate material within the epithelial cytoplasm may indicate phagocytic as well as absorptive activity of cells. Based on a common neuroepithelial origin and similar histochemical properties, we conclude that the paraphysis is a modified choroid plexus. The velum transversum is an arbitrary boundary between diencephalon and telencephalon, and is itself formed of choroid plexus. The medial telencephalic ventricle is the rostral portion of the third ventricle. All neuroepithelial infoldings at the rostral end of the diencephalic roof including the velum transversum are intraventricular choroid plexuses; the neuroepithelial outpouchings in this region are the extraventricular choroid plexuses (paraphysis) of the diencephalon.
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  • 50
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The left ovary of the bonnethead shark, Sphyrna tiburo, is rudimentary, and the right ovary supplies both oviducts which share a common ostium situated in the falciform ligament. Preceding ovulation the nidamental gland of each oviduct hypertrophies and the caudal two-thirds of each oviduct is modified to form a uterus. In the Florida-Caribbean area Sphyrna tiburo probably mates in March and 3-7 eggs are fertilized in the vicinity of the nidamental gland of each oviduct.The developing embryo is nourished during the first 3-4 months of gestation by yolk stored in its extensive yolk sac. Approximately three and one-half months after fertilization, the distal portion of the yolk sac becomes convoluted and interdigitates with deep folds in the uterine wall to form a yolk-sac placenta. As the placenta develops, the maternal uterine epithelium is reduced from columnar cells to squamous cells, and the foetal yolk-sac epithelium is reduced from columnar and cuboidal cells to squamous cells. Exchange between the maternal and foetal blood systems takes place through maternal endothelium, reduced maternal epithelium, egg-case membrane, reduced foetal epithelium, and foetal endothelium.
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  • 51
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    Journal of Morphology 120 (1966) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 52
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    Journal of Morphology 120 (1966), S. 347-358 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histochemical methods for mucins were applied to the ovaries of 23 dogs.Solid and hollow groups and cords of epithelial cells (subsurface epithelial structures, SES) in the outer part of the cortex regularly showed evidence of mucin secretion. Intracytoplasmic, sialic acid-containing, acid mucin secretion droplets were seen in solid and hollow SES, and secretion was present in both closed lumina and those opening onto the surface.Intracytoplasmic droplets in the cells of SES were distinctive, and similar droplets were not found in the cells of any other ovarian epithelial component. The secretion of SES was not shown to possess distinctive histochemical features.Mucin production was also observed in follicles, corpora lutea and rete tubules.The significance of ingrowth from the ovarian surface epithelium in adult life, and of secretory activity by the cells of SES, are discussed.
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  • 53
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    Journal of Morphology 121 (1967) 
    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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  • 54
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This is the last of a series of observations involved in a comparative histological study of the ultimobranchial body in vertebrates. Complete serial longitudinal or transverse paraffin sections were made of formol alcohol, Bouin's, and formalin-fixed ultimobranchial and thyroid tissues that had been removed from adult specimens of the cat, cotton rat, ground squirrel, Guinea pig, kangaroo rat, bushytailed wood rat, rabbit, and raccoon. The alcian blue-PAS, aldehyde fuchsin-alcian blue, mucicarmine, alcian blue-safranin, Best's carmine, and toluidine blue staining procedures show that the glandular mammalian ultimobranchial tissue is capable of producing considerable amounts of various mucosubstances, particularly the acid mucopolysaccharides, and other carbohydrate-containing materials. The carbohydrate moiety has been histochemically identified as mucopolysaccharides possessing acidic groups, those having both carboxyl and ester sulfate groups; and as glycogen, muco-and glycoproteins and other carbohydrate-protein complexes. The differences in the intensity and localization of a given staining reaction reflect not only individual and species variations but also significant differences in the position of the ultimobranchial tissue in relation to the thyroid gland. An accessory thyroid lobule found near parathyroid IV and thymus IV in a bushy-tailed wood rat may represent a cystic manifestation of the ultimobranchial body because its follicles varied greatly in size and were lined by a thick stratified squamous epithelium. The possible hormonal mechanisms (TSH, thyroxine) involved in the regulation of ultimobranchial activity are discussed in relation to the gland's production, storage, and release of mucopolysaccharides and other secretory substances.
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  • 55
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An electron microscope study of oocyte maturation in the mouse revealed that some mitochondria undergo gradual transformation in their ultrastructural appearance. In very young oocytes these mitochondria were already found to contain vacuoles, one in each such organelle. In somewhat older oocytes more mitochondria displayed vacuoles which generally appeared to be getting larger. These intramitochondrial vacuoles were found to be essentially optically empty structures surrounded by a single membrane. In favorable sections someof the developing vacuoles had a bottle-shaped appearance, the constricted end of which was attached to the inner limiting membrane of the mitochondrion. With further maturation of the oocytes vacuoles having a pear-shaped appearance became evident. An hypothesis was presented outlining the mode of formation of these vacuoles by expansion of the individual cristae. Intramitochondrial transformations occuring during both oogenesis and spermatogenesis in mammals were reviewed.
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  • 56
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    Journal of Morphology 121 (1967), S. 103-133 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The monotypic perciform suborder Luciocephaloidei possesses the following, previously unknown, salient morphological characters: a third joint, the nasopalatopterygoid, between neurocranium and suspensorium; a toothless and dorsally exposed prevomer; no pharyngeal processes on either parasphenoid or basioccipital; a tympanum-covered foramen exoccipitale in the saccular bulla as a hearing organ; a gular ossification; a craniovertebral joint with small exoccipital condyles widely separated from the basioccipital condyle; and a large physoclystic swimbladder with a notable caudal extension. The seemingly functionless gular-like mental ossification is considered a paleomorphic structure with a neogenetic development. Attenuation in longitudinal growth is evident in the derivatives and dermal additions of the mandibular arch and nasal capsule while other regions of the head have remained independent. The primary adaptive significance of the attenuation in the growth of the entire preorbital region is the accomodation of oral incubation. Secondarily the elongate jaws increase both the speed and grasping range of the bite in prey catching. The degree of jaw protrusion depends mainly on the length of the maxillary. The exaggerated length of the ascending processes of the premaxillaries may be the result of a positive differential growth rate within one growth field. The meaning of the preponderance of parallel-fibered cranial muscles is discussed in respect to holding functions, greatest possible excursion of the insertion with minimum loss of force, and muscle fiber length. Based on the overall morphology, the monotypic suborder Luciocephaloidei is retained.
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  • 57
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    Journal of Morphology 121 (1967), S. 135-157 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Osteology, myology and motion analysis of the head of the anabantoid fish Helostoma temmincki, a specialized filter feeder, has revealed six functional units: neurocranium, suspensory apparatus, opercular apparatus, hyoid apparatus, branchial apparatus and pectoral girdle. Interactions between the functional units take place through four couplings involved in opening and protruding the jaws. The first coupling is activated in the beginning of the opening cycle by the levator operculi muscle through the opercular apparatus, interoperculomandibular ligament and mandible. The second is activated during feeding by contraction of the sternohyoideus through the hyoid apparatus, interopercular, interoperculomandibular ligament and mandible. The third coupling is active during feeding and “kissing” by contraction of epaxial muscles through mediation of the neurocranium to the jaw apparatus. The fourth coupling is the only one active during air intake and involves contraction of the levator arcus palatini which abducts and rotates the suspensory apparatus forwards, causing the mandible to drop. The retention of isolated ancestral characters during mosaic evolution are explained in terms of the maintenance of couplings which represent functional associations of seemingly remote structures. When natural selection acts on one component of a functional unit or coupling, it essentially acts on all associated elements simultaneously causing character complexes to evolve in common evolutionary trends. It is feasible that functional analysis can separate primary from secondary evolutionary trends.
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  • 58
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    Journal of Morphology 122 (1967), S. 89-114 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Large dogs are able to deliver a powerful bite that generates considerable stress in the anterior, prehensile part of the jaws.In the upper jaw most of the biting force is borne by the anterior teeth. The palatal mucosa provides little resistance to deformation. It is easily compressed and rather mobile.In the lower jaw, the mucosa covering the upper surface of the symphysis receives a sizeable portion of the biting force. It is firmly attached to the underlying bone and possesses special connective tissue arrangements that enable it to transduce locally applied pressure to tension distributed over a broad area.
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  • 59
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Goldfish testes were nutritionally regressed in about 115 days regardless of season and without controlled light or temperature. A gonosomatic index (testes weight ″ 100/body weight) of the regressed fish was about one tenth that of spawning fish. The regressed testes were primarily composed of spermatogonia, spermatocytes, and connective tissue. Fish testes were maintained in a regressed state for over 200 days with no change in gonosomatic index. Fish with regressed testes appeared to be in a state of “pseudohypophysectomy” with respect to gonadotropin. Pituitary replacement and a diet of 5% of the body weight per day initiated spermatogenesis and brought the regressed testes to functional maturity in one month. The results suggest that spermatogonial proliferation and the maturation of sperm have different regulatory requirements.
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  • 60
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    Journal of Morphology 123 (1967), S. 1-16 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A theoretical analysis is made of the mechanical advantages of exoskeletons and endoskeletons. More complicated and realistic loading systems are considered than have been by previous authors. For all cases involving static loading, an exoskeleton would seem to be advantageous, but sometimes the advantage is quite small. If impact is considered, the advantage of exoskeletons becomes very much reduced, even on theoretical calculations; and it is likely that in life the advantage may be converted to a disadvantage, particularly in large active animals such as vertebrates.
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  • 61
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    Journal of Morphology 123 (1967), S. 43-61 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Silver stained Cordylophora were examined by light and electron microscopy, which provided a general picture of nerve cell forms and distribution for comparison with electron micrographs of osmium-fixed tissues from the same hydroid. Muscle, nerve and neurosensory components were studied in the nectophore of Nanomia (O. Siphonophora) and in the hydromedusae Sarsia and Euphysa by means of vital staining and optical and electron microscopy of epon sections; particular attention was given to relationships and interconnections between the cellular elements of the two marginal nerve rings. Mitochondrial size, numbers and types of vesicles and the occurrence of neurotubules and of parts of sensory cilia may provide useful ultrastructural clues for recognizing nerve elements, but serial sections are often needed to make identification conclusive.In Cordylophora and Nanomia, some neurites contain massed A vesicles (membrane-bounded dense granules) suggestive of neurosecretion (cf. reports on Hydra). However, a small type of A vesicle also occurs at synapses in Sarsia, indicating a probable role here in junctional transmission. Vesicles occur on both sides of some synapses (as previously reported for Cyanea) but on one side only in others, these being the first examples of polarized junctional ultrastructure in coelenterates.
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  • 62
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    Journal of Morphology 123 (1967) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 63
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    Journal of Morphology 123 (1967), S. 231-249 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A correlated light and electron microscope study was made of lymphocyte-epithelial relations in the appendix of normal rabbits, ranging in age from one week to ten months. The lymphocyte migration into the epithelium was very slight at one week. The lymphocytes were increased considerably in number from two weeks to three months, grouping into unique nests in the epithelium. The basement membrane began to be penetrated by migrating cells at one week and bacame discontinuous in older animals. At one and two weeks, the epithelial cells contained glycogen, which disappeared at three weeks. Degenerating cells as well as bacilli were found in the epithelial cells and in the macrophages of the nodules. The varied appearance of bacilli in the macrophages indicates that they were being digested. The lymphocytes in the epithelium were larger, having less crowded cytoplasm as compared with those in the lymph nodules. Many lymphocytes were in deep folds of epithelial cells. There was evidence favoring an intracellular position for some lymphocytes in the epithelium.
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  • 64
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: White Leghorn eggs were incubated to desired prevasular stages. Each embryo, upon its intact yolk and surrounded by albumen, was rolled from the shell into a sterile 50 ml beaker. In an uppermost position, the blastoderm was lightly stained with neutral red. Three types of localized cuts were made as indicated below, and the beaker-embryo unit placed in a sterile humidified chamber for further incubation. Results: (1) Unilateral cuts adjacent to the body and parallel with its axis blocked or suppressed formation of the vitelline artery on the cut side, even though healing occurred; (2) A specific site was found in the area pellucida opposite the sinus rhomboidalis which, when lightly cut perpendicular to the body axis, resulted in blockage or shifting of the final junction between aorta and vitelline artery as far cephalad as the thirteenth somite level. Formation of a dual final junction with the aorta also occurred. (3)Transverse cuts through the body axis and into the area pellucida bilaterally, frequently resulted in bilateral blockage or bilateral shifting. In still other cases, growth of a functional loop around the cut to connect the aortae in anterior and posterior segments with the vitelline artery were observed. Other unique circulatory patterns are described.Apparently, slight interference with the capillary plexus which precedes the vitelline artery causes anomalous development. Circulation is considered a major factor in arterial differentiation. Cutting probably alters the plexus and relation of its components to the onset of blood flow.
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  • 65
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Branches of the coronary arteries of normal human hearts, supplying both atria and ventricles, were found by fine dissection and have been named rami atrioventriculares. They comprise atrial branches from ventricular arteries and ventricular branches from atrial arteries. Their incidence was 74% in the 50 adult individuals studied. The subjects had committed suicide with a poison which did not damage the coronary arteries. The atrioventricular branches constitute communications across the coronary sulcus, thus establishing a continuity between the atrial and the ventricular arterial supply. Therefore, there is not invariably a sharp demarcation of blood supply between atria and ventricles, as has been commonly taught. Neither atrial nor ventricular branches consist exclusively of ascending and descending branches of the coronary arteries, as has been assumed. Atrioventricular branches can play a role in collateral circulation and may, in individuals who are born with them, provide an explanation for some of the variability in signs and symptoms incidental to heart attacks.
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  • 66
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paper deals with the development of the salivary gland system in Melipona quadrifasciata anthidioides, which begins in the prepupal stage. The silk glands degenerate by autolysis at the end of the larval stage. Degeneration is characterized by cytoplasmic vacuolization and pycnosis of the nuclei of the secretory cells. The glandular secretory portion of degenerated silk glands separates from the excretory ducts. The salivary glands develop from the duct of the larval silk glands. The thoracic salivary glands develop from the ducts of the secretory tubules and the head salivary glands from the terminal excretory duct. The mandibular glands appear in the prepupa as invaginations of mandibular segments, and their differentiation to attain the adult configuration occurs during pupation. The hypopharyngeal glands have their origin from evaginations of the ventral anterior portion of the pharynx. A long tubule first appears with walls formed by more than one cellular layer. Then some cells separate from the lumen of the duct, staying attached to it by a cuticular channel in part intracellular. The initial duct constitutes the axial duct, in which the channel of the secretory cells opens. During the development of salivary and mandibular glands, they recapitulate primitive stages of the phylogeny of the bees. During the development of salivary glands system, mitosis accounts for only part of the growth. Most of the growth occurs by increase in size of cells rather than by cell division. In brown-eyed and pigmented pupae six days before emergence, the salivary gland system is completely developed, although not yet functioning.
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  • 67
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The caudal anatomy (caudal skeleton, musculature, vascularization, innervation, and urohypophysis) and swimming behavior of three clupeiform and three perciform fishes: Elops hawaiensis (Cupeiformes: Elopidae), Oncorhynchus nerka (Cupeiformes: Salmonidae), Chanos chanos (Clupeiformes: Chanidae), Kuhlia sandvicensis (Perciformes: Kuhlidae), Apogon menesemus (Perciformes: Apogonidae), and Gnathanodon speciousus (Perciformes: Carangidae), were studdied. The taxonomic significance of caudal structures was determined and evaluated by detailed examination of differences in caudal anatomy. An interpretation of functional significance of these differences was attempted by relating them to observed differences in swimming behavior. The swimming behavior was studied by the observation of swimming activities of fish while resting or cruising and while feeding in the aquarium, and by an analysis of each frame of an 8 mm movie film of swimming activities.There are certain consistent and basic differences between all three species of the order Clupeiformes and all three species of the order Perciformes in respect to caudal structures. Although certain caudal structures show overlapping in number and/or complexity of arrangement, they seem to indicate more complex structural organization in Clupeiformes than Perciformes. The differences confirm the conclusion of others that the order Clupeiformes is more “primitive” than the order Perciformes.With respect to caudal structures of the three clupeiform species studied, E. hawaiensis is the most “primitive” and, of the three perciform species studied, K. sandvicensis is the most “primitive.”Caudal structural variations from one species to another are related to the mode of adaptation to swimming as well as to the evolutionary status of the species.
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  • 68
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    Journal of Morphology 124 (1968), S. 37-77 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cells surrounding a wound in the integument of Rhodnius adults show an increase in RNA content, cytochrome oxidase and esterase activity. An excision in the integument is filled by blood which coagulates and is tanned into an insoluble membrane. The basement membrane of the adjoining epidermis acts as a self-sealing membrane and contracts to cover the excision. The epidermis is attached to the cuticle by the subcuticular layer which it resorbs and by pore canal filaments which are left behind as it migrates. The epidermis migrates as a sheet in contact with the cuticle then with the coagulated blood and basement membrane which cover the excision. Blood cells migrate individually into an excision and do not adhere to a surface in the process. Microtubules cannot be identified with movement. Both epidermal and blood cells remove the cells killed by wounding as evidenced by the appearance of coated vesicles and phagocytic bodies in both cell types. The reconstituted integument consists of a surface membrane in which the layers of the epicuticle are not distinguishable, a nonlamellate cuticle secreted by an epidermis which also appears to secrete the new basement membrane.
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  • 69
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    Journal of Morphology 124 (1968), S. 295-311 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of intraneural vessels was studied in response to an induced hypermorphosis of neural tissue inthe midbrains of 38 chick embryos ranging in age from three days through 14 days of incubation. The pattern of vascularization was compared with that of normal chick embryos at comparable stages of development. In the experimental embryos, the increase in mitotic figures along the ventricular borders of the mesencephalon is accompanied by the establishment of an endoneural plexus approximately one day earlier than is the case during normal vascularization of the midbrain. This plexus also penetrates more deeply and extensively into the ependymal layer. Surface vessels and intraneural vascular elements are dilated, and the cerebrospinal fluid contains varying amounts of blood released from large intraneural vessels which protrude into the ventricle. The most prominent cerebrovascular effects seem to occur between the fourth and eighth days of incubation. Thereafter, the cerebrovascular pattern becomes more normal except for relatively few isolated hemorrhagic areas.
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  • 70
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    Journal of Morphology 124 (1968), S. 345-351 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The eye of Haideotriton wallacei is more reduced histologically than those of othe troglobitic salamanders. The tiny eye is imbedded in a mass of adipose tissue. No extrinsic eye muscles are present. A rudimentary lens is present in about half of the eyes examined. In two instances the lens is surrounded by a small chamber; most eyes lack a chamber. The retina and iris are relatively undifferentiated. The relatively massive retina lacks rods and cones, an outer plexiform layer and subdivided nuclear layers. A tiny optic nerve runs to the brain.
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  • 71
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The aesthetascs, short thin-walled pegs on the antennule flagella of Coenobita clypeatus, a terrestrial hermit crab, are similar to those of other decapod crustacea in containing the dendrites of many bipolar neurons whose cell bodies are grouped in spindle-shaped masses beneath the bases of each hair. The dendrites contain rootlets, basal bodies, and cilia, which divide dichotomously before entering the aesthetasc, so that within the hair, each cilium becomes represented by a group of slender branches.The aesthetascs themselves are short, blunt, and partially recumbent so that each has an exposed and an unexposed side. The cuticle on the exposed side is thinner and more tenuous than that on the protected side, and the dendrite branches are concentrated just underneath. The protected side, on the other hand, is lined with nondendritic supporting cells, and the cuticle is thicker, more lamellar, and probably less permeable.All dendritic elements proximal to the dendrite branches are enclosed within the main body of the antennular flagellum, and the initial segments of the cilia lie within a vacuole. In these respects, the aesthetascs of Coenobita resemble the thin-walled pegs on insect antennae more than they do those of the marine decapods thus far examined. This convergence in the terrestrial forms may be in response to the need to conserve water.
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  • 72
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Brittle Star digestive system is composed of buccal, pharyngeal, esophageal and stomach cavities. The buccal and pharyngeal cavities are lined by columnar cells covered by a cuticle, and are apparently concerned with mucous production. Coelomocytes and tall columnar cells are described in the esophagus and stomach epithelia. The columnar cells are adapted for nutrient absorption, enzyme synthesis, and lipid storage. Nerves are found beneath the epithelia within a connective tissue layer. Smooth muscle and coelomic layers lie external to the connective tissue layer. The coelomic layer lines a perivisceral space and has diverse modifications of its perivisceral surface; a pedicle-cuticle modification perhaps having general significance in echinoderms.
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  • 73
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    Journal of Morphology 125 (1968), S. 61-70 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two complete composite photographs of the optic nerve of Limulus, made by electron microscopy, reveal the presence of neurosecretory granules in the large axons of the rudimentary eye neurons. The number of intermediate sized, (3-7 μ), of eccentric cells corresponds with the number of ommatidia as expected, but only their sheath of Schwann cells show an intimate interfolding. Based on the number of fine axons within the nerve each ommatidium has an average of 12-13 retinular cells. The diameter of their fibers is between 0.2 and 3 μ although the majority are between 1 and 1.5 μ. They are aggregated into bundles of six to seven fibers by the sheath cells although some bundles contain only two, others as many as 181 fibers. There is no indication in these studies that retinular cell axons within a bundle are associated with the same, adjacent, or other pattern of ommatidia. The photographs suggest that physiological activity in retinular cell axons might be detected most easily in the smallest bundles because they contain the fewest, but the larger retinular cell axons.
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  • 74
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The lateral and ventral external surfaces of the third and fourth abdominal segments were described and muscle attachments were correlated with surface indentations of the larva. The proleg of this species has a symmetrical planta with a complete circle of crochets. Furthermore, it differs externally from the grasping type of proleg in having a largely membranous coxal region confluent with the body wall, and a relatively large subcoxal lobe.The body wall musculature and innervation of the third and fourth abdominal segments are similar in many respects to those described for other lepidopteran larvae to which they are here compared, but differ from most because of the simpler structure of the prolegs which lack highly developed adductor muscles. Like most muscles innervated by the ventral nerve, the principal plantar retractors of these two segments cease to function in the first day of the pupal stage and have completely degenerated by the forty-fifth hour of pupal life. The ventral nerve retains its four primary branches in the adult, in which many smaller rami can be traced to the cuticle and to the neoblastic body wall muscles.
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  • 75
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gross anatomy of muscles, the topography of nerve tissues, and the histology of the pregenital abdominal glands of Nomia melanderi Ckll. are reported in detail. The movable and fixed points of muscle attachment were utilized in establishing a system of nomenclature for a typical abdominal segment. Names of nervules correspond to those of the tissues they innervate. The points of attachment of muscles of the fifth abdominal segment are essentially the same in both Nomia and Apis, except for the second tergo-sternal muscle which, in Nomia, has shifted its point of movable attachment to the membranous integument in front of the intersegmental membrane gland where it helps in relasing glandular secretion. The general plan of the nerves in the fifth abdominal segment in Nomia is more diffuse than in Apis, but there is no difficulty in establishing homology between the nervules of the two species. A pair of intersegmental stretch organs was found in abdominal segments 3-6. Glands of the sixth intersegmental membrane possess a reservoir with peripheral pouches both of which are absent in those of the fifth. Both types of glands have neither closing nor opening mechanisms, and neither is innervated. Release of glandular secretion is accomplished by the action of the tergo-sternal muscles.
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    Journal of Morphology 125 (1968), S. 253-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report describes the capacity of larvae of the Leopard frog, Rana pipiens, to regenerate pineal tissue after embryonic pinealectomy, and presents experimental evidence for frontal organ dependence on the epiphysis. In addition, it was found that the “brow spot,” a pigment-free region located in the epidermis betweeen the eyes, is dependent on the frontal organ for its formation. This report also substantiates that the absence of the pineal organ in larval animals does not affect growth or development through metamorphosis.
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  • 77
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    Journal of Morphology 125 (1968), S. 315-328 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Interest in the structure of the antennae of the Florida Queen butterfly arises from the finding that a pheromone is active in their courtship. Light and electron microscopic techniques were used to study the sensilla on the antennae and three types of sensilla with perforated walls were identified. The most common of these are short, thin-walled pegs which are distributed over most of the antennal surface. Long, curved, thin-walled pegs occur in patches on the inner medial antennal surface. Multiple coeloconic sensilla are present having up to 50 pegs in one sensillum. On the outer 28 flagellar subsegments there are two such sensilla per subsegment. In addition there are on the antennae long, thick-walled hairs which are mechanoreceptors and probably also contact chemoreceptors. Sunken pegs, the function of which is not known, occur on the antennae. Grooved sensilla were found with the electron microscope but could not be identified with the light microscope. There was no indication of sexual dimorphism in sensilla types or numbers on the antennae.
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  • 78
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    Journal of Morphology 125 (1968), S. 403-417 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Succinic dehydrogenase, NAD and NADP diaphorases, choline oxidase, d-amino acid oxidase, α-glycerophosphate dehydrogenase, glutamic dehydrogenase, lactic dehydrogenase and aldolase were identified histochemically in the esophagus and proventriculus of the developing chick embryo. In general, the deep glands of the proventriculus reacted more strongly than the epithelium and mucous glands of the esophagus to the tests. The intensity of the enzymatic activity seems correlated with the number of mitochondria and metabolic activity of the cells.
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  • 79
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    Journal of Morphology 126 (1968) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 80
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Two kinds of tactile hairs, plain and wavy, thick-walled chemoreceptors and two types of thin-walled chemoreceptors are present on the antennal flagellum of Gromphadorhina portentosa males. These are described and their location on the antenna noted. Females of this species have plain tactile hairs and the same types of chemoreceptors as do the males but wavy tactile hairs are absent. The antennal sense organs of a few specimens of five other species of cockroaches  -  Periplaneta americana, Blatta orientalis, Supella longipalpa, Pycnoscelus surinamensis and Diploptera punctata  -  were also examined. All lacked tactile hairs but were provided with thick-walled chemoreceptors and with two types of thin-walled chemoreceptors similar to those described for Gromphadorhina portentosa.
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  • 81
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    Notes: Pulse labeling with tritiated thymidine has permitted the identification of a progenitor cell compartment at the base of the hypostomal glandular ridges of the marine hydroid Podocoryne carnea. This progenitor compartment produces cells which move out on the ridges differentiate as digestive gland cells, and are ejected into the gastro-vascular cavity. Spherous gland cells of the body appear not to be part of this circumscribed replacement system. There appears to be no proximal movement of gastrodermal cells in the body of this marine hydroid.
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  • 82
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Among eight species of mammals in this study (cattle, sheep, pig-tail and rhesus monkeys, rabbit, pig, rat, and dog) four basic patterns of anatomical structure at the uterotubal junction are described. The classification of types is based upon the presence or absence of an intramural portion of the oviduct and of isthmal folds or plicae projecting into the lumen of the uterine cornu.Histological variations are reported for three tissues: epithelial and connective of the mucosa and smooth muscle of the tunica muscularis. In the epithelium during the estrous cycle the differences recorded include: (a) absence of ciliated cells in the distal end of the oviduct in rat and dog; (b) variations in ciliated and nonciliated cells in (1) cell height, (2) location, shape and stainability of the nucleus, and (3) in amount and stainability of apical cytoplasm; (c) presence of lymphoblast-like cells which appear to migrate through the epithelium from the lamina propria. The connective tissue of the mucosa, as a circular layer and as cores for the mucosal folds, shows variations in thickness and in relative density of cells and fibers of the matrix. Emphasis is given to the presence of an inner longitudinal layer of smooth muscle in the tunica muscularis of the distal oviduct in six of the eight species.
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  • 83
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    Journal of Morphology 125 (1968), S. 259-279 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of cells in the colleterial glands of the Cecropia silkmoth was examined. Morphologically and functionally the gland is divided into two regions, a tubular one in which columnar protein-synthesizing cells are located, and an expanded region in which flattened cells with very different structure are most prominent. The fine structure of the latter cells which are presumed to secrete a phenolic glucoside, closely resembles that of cells described in the colleterial glands of orthopterans. The protein-secreting cells have many features normally associated with pancreatic acinar, and other cells of similar function. Among these are extensive rough endoplasmic reticulum, an elaborate Golgi complex, and a modest number of mitochondria. Other features which are less usual in cells of this type are an elaborate secretory apparatus consisting of a cuticular tubule inserted into a microvilli-lined cavity at the apical end of the cell, and large numbers of cytolysomes, myelin figures, and lipid droplets. A chitogenous cell with a very distinct and specific type of ultrastructure is found associated with the secretory cell. This cell type is attached to the cuticular elements of the gland, and the main features of its cytoplasm are extensive bundles of microtubules which presumably serve as supportive elements for the secretory cells.
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  • 84
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    Journal of Morphology 125 (1968), S. 329-365 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryonic chick myocardium (stages 8+ to 12-) was studied by light and electron microscopy. The myocardium, which is initially comprised of radially oriented cells with large intercellular spaces gradually becomes more tightly packed. Intercellular spaces decrease and the cells assume a circumferential orientation. Myocardial cells remain epithelial throughout formation of the functional tubular heart and specialized epithelial junctions (apical junctional complex or terminal bars) undergo modification to form intercalated discs. Embryonic myocardial cells contain large amounts of free ribosomes and particulate glycogen, the latter often associated with portions of granular reticulum. Unlike developing skeletal muscle. The amount of granular reticulum contained in the myocardial cell cytoplasm is large and, along with a hypertrophied Golgi apparatus, suggests that these cells may have a secretory function. These organelles persist during the initial period of fibril formation. Myofibrils apparently form from non filamentous precursor material and not by alignment of sequentially synthesized components.
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  • 85
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    Journal of Morphology 125 (1968), S. 379-401 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The characteristic anoline climbing organ consists of a number of lamellar scales, on whose outer scale surface are numerous keratinized setae which contact the substrate. These setae are derived from the Oberhautchen of the epidermal generation, and as such are renewed and shed periodically along with the rest of the epidermal material. The histological development of the setae is described, and modifications of the surrounding elements are noted. The relative lengths of the setae and their congregation to form a pad unit poses certain mechanical problems during morphogenesis, simply in terms of accommodation between the functional outer epidermal generation and dermal core of each lamella. Regression of the dermal core and a distal migration of some cells permits accommodation within the lamella for the distal aspect of the Oberhautchen layer, or free margin. Additionally, changes in the gross shape of the lamella occur throughout the sloughing cycle, and a swelling of the cells of the lacunar tissue results in a gap between the stratum corneum of inner and outer epidermal generations. There is a considerable amount of variation in mitotic activity between the germinal layers of opposite sides of the lamella.
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  • 86
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Function and ultrastructure of the excretory organs (antennal glands) of the shore crab Uca mordax were investigated. The crabs were maintained at three different salinities: 50%, 100% and 200% seawater. In spite of previous reports to the contrary, the investigation showed that the powerful osmoregulatory ability found in Uca mordax is not due to participation of the antennal glands. Freezing point depression of urine under all conditions was found to be slightly less than that of the hemolymph, indicating a slightly hypoosmotic urine. It was further found that the antennal gland is extremely effective in resorbing sodium from the filtrate. The higher the salinity to which the crabs were acclimated the lower the sodium concentration in the urine. No water was resorbed from the filtrate as shown by the fact that the inulin U/P ratio remained unity regardless of the salinity to which the crabs were adapted. Electronmicroscopy of the antennal glands revealed that the coelomosac cells are similar to the podocytes described in the crayfish by Kümmel ('64), and the coelomosac appears to be a typical filtration organ. The cells of the labyrinth showed brush border and very elaborate basal infoldings with numerous mitochondria. The deep cytoplasmic infoldings which represent interdigitations with neighboring cells may be correlated with the effective sodium reabsorption in the labyrinth, but apparently not with water movement.
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  • 87
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    Journal of Morphology 126 (1968), S. 31-65 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitochondria in early spermatids of many insects aggregate and form a round body, the nebenkern. The nebenkern undergoes a structural differentiation and then divides into two separate equal-sized bodies. In the present study, nebenkerns of Murgantia histrionica, a Hemipteran insect, were reconstructed using electron micrographs of serial sections to determine how the mitochondria transform into the two separate bodies.Newly formed nebenkerns are made of one piece, an anastomosis of rod-like segments. Some segments interconnect to join networks of rings. Each network interlocks with another similar network, but networks which interlock are connected with each other by other segments of the nebenkern. Later, the entire nebenkern is made of two unconnected and interlocked networks of rings. The nebenkern appears to remain bipartite during subsequent differentiation. Since the two pieces are interlocked, breaks must occur before the pieces can separate. As breaks occur, each network transforms into a set of curved sheets, producing a nebenkern made of four concentric layers. The three outer layers are each made of two curved sheets which surround a bipartite central core. The surface sheets meet at a furrow in the surface of the nebenkern; segments in each layer are roughly symmetrical with each other about the plane in which the furrow lies. Rod-like segments join alternate segments. The number of layers then decreases to three, and later, to two. These nebenkerns resemble four-layered nebenkerns, but fewer connections between alternate segments are present. The two pieces constituting the nebenkern probably separate after most of the latter connections disappear. Hypotheses to account for the observed changes in nebenkern structure are presented.
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  • 88
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  • 89
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    Journal of Morphology 126 (1968) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 90
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    Journal of Morphology 127 (1969), S. 177-203 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The venom system of Nasonia vitripennis is well-developed and composed of an unbranched acid gland and associated reservoir. Fine-structural, histochemical and electrophoretic studies indicate that the venom is produced by two protein-secreting epithelia. The bulk of the venom is synthesised in the columnar cells of the acid gland and discharged via “vesicular organelles” and the efferent ductular system into the lumen of the reservoir. The acid gland also contains squamous chitogenous cells, situated either around the central lumen or interposed between the bases of the columnar cells. Once within the reservoir, the venom is probably activated by enzymatic secretions from the reservoir secretory cells. Each of these cells has a “vesicular organelle” but, in contrast to the columnar cells of the acid gland, the cytoplasm contains a preponderance of free ribosomes, and protein segregation apparently occurs outside the Golgi complexes.The venom is expelled through the efferent discharge duct by muscular contractions, which open the duct lumen and bring it into contact with the funnel of the ovipositor. Excessive distortion of the duct is prevented by a massive ventral ligament.
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  • 91
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    Journal of Morphology 127 (1969), S. 233-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: There are eight retinula cells in the ommatidium of the compound eye of the toadbug (Gelastocoris oculatus), two of which are central in position. Along the axial sides of the six peripheral retinula cells expand six cytoplasmic processes from the apical crystalline cone cells. These processes, which contain longitudinally-oriented microtubules, are associated with all eight retinula cells by means of desmosomal junctions. In addition to providing structural support, the possibility is set forth that the interconnecting cone processes might also serve to functionally integrate the retinula cells of an ommatidium. The eight retinula cells possess microvillus surfaces, which are especially prominent in the six peripheral cells, where they extend into the lumen of the ommatidium. There is evidence of pinocytotic activity at the bases of microvilli. Multivesicular bodies are present in the cytoplasm of retinula cells, and the means by which these bodies might be elaborated are discussed.
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  • 92
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    Topics: Biology , Medicine
    Notes: The mechanism of respiration in the bullfrog has been analyzed by means of pressure recordings from the buccal cavity, the lungs and the abdominal cavity, by cinematography and cinefluorography, and by electromyography of buccal, laryngeal and abdominal muscles. Gas flow was investigated by putting frogs in atmospheres of changing argon and nitrogen content and monitoring the concentration of the nostril efflux.Three kinds of cyclical phenomena were found. (1) Oscillatory cycles consist of rhythmical raising and lowering of the floor of the mouth, with open nares. They have a definite respiratory function in introducing fresh air into the buccal cavity. (2) Ventilatory cycles involve opening and closing of the glottis and nares and renewal of a portion of the pulmonary gas. More muscles are involved and the pattern of muscular activity is more complex than in the oscillatory cycles. (3) Inflation cycles consist of a series of ventilation cycles, interrupted by an apneic pause. The intensity of the ventilatory cycles increases before this pause and decreases immediately thereafter. This results in a stepwise increase in pulmonary pressure, to a plateau (coincident with the pause) followed by a sudden or stepwise decrease.The respiratory mechanism depends on the activity of a buccal force pump, which determines pulmonary pressure whose level is always slightly less than the peak pressure values of the ventilation cycles. The elevated pulmonary pressure is responsible for the expulsion of pulmonary gas during the second phase of the next ventilation cycle. This pressure is maintained by the elastic fibers (and the smooth masculature) of the lungs.
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  • 93
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    Notes: The complete regeneration of a new oral-disc and tentacles has been observed and described for Aiptasia diaphana. These structures are regenerated quite rapidly: seven to ten days at 20°C. At three days post-amputation, the new primary, secondary, and tertiary tentacle buds begin to develop in direct association with the underlying primary, secondary, and tertiary septae (respectively) of the column, suggesting that the latter organize the form of the regenerating oral-disc. Two days after amputation, the zooxanthellae of the presumptive oral disc arrange themselves into a ring which quite precisely delimits the area from which the tentacle buds will form. In spite of its suggestive proximity, this accumulation of algae plays no role in the induction of tentacle buds as was shown by studying regeneration in anemones which essentially lacked large quantities of these symbiotic algae.Cuts perpendicular to the longitudinal axis of the column result in an equal rate of tentacular regeneration around the entire circumference of the presumptive oral disc. Oblique amputations foster an asynchronous regeneration: the tentacle buds of the distal-most area of the severed column are larger and regenerate much sooner than those of the proximal region. Similar results were obtained by studying anemones which were cut perpendicular to their longitudinal axes at different levels along the column. The data suggest that an oral-aboral gradient exists concerning the time required for the initiation of tentacle budding and the rate of tentacle regeneration.
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  • 94
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    Journal of Morphology 128 (1969) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 95
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A rapid method for examining rat fetuses is presented. The technique consists of fixing the fetuses in Bouin's solution, serially sectioning the head, neck and lower trunk with a razor blade and doing sagittal sections of the heart after opening the thoracic cavity. Examples of sections from normal 20 day rat fetuses are given as well as some with the following abnormalities: cleft palate produced by chlorcyclizine and eye and heart malformations resulting from anti-adult rat kidney serum.
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  • 96
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    Journal of Morphology 127 (1969), S. 7-39 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A structure for a generalized insect epidermal cell during the formation of the epicuticle is proposed, based on studies of several different epidermal cell types. The protein epicuticle is defined as the dense homogeneous layer below the cuticulin. The formation of the protein epicuticle involves secretory vesicles arising in Golgi complexes, and marks an interlude in the involvement in cuticle formation of plasma membrane plaques. The plaques are concerned in cuticulin formation before and in fibrous cuticle formation after the deposition of the protein epicuticle.The epidermis is characterized by the possession of a cytoskeleton of microtubules and a matrix of microfibers. In the elongated cells forming bristles and spines, the microfibers are often oriented in bundles with an axial banding which repeats every 120 Å. The microtubules are also arranged in columns with a trigonal packing and center to center spacing of about 800 Å. These cytoskeletal structures separate the other organelles into channels which may restrict the pathways open for the movement of secretory and pinocytotic vesicles. The protein epicuticle arises from the secretory vesicles which discharge at the apical surface. The contents disperse and reaggregate below the cuticulin. The Golgi complexes in the basal and central regions have many secretory vesicles and a small saccular component, differing from those nearer the apex which are smaller and have fenestrated saccules. The small coated vesicles (800 Å in diameter) associated with both sorts of complex, probably move to the apical and basal faces of the cell where they may give rise to the large coated vesicles (2000 Å in diameter) inserted in the plasma membrane. Pinocytosis occurs from both apical and basal faces but most lytic activity is in the apical region. Plant peroxidase injected into the haemocoel is taken up basally and transported to the apical MVBs. The large coated vesicles on the apical face may be concerned in the control of the extracellular subcuticular environment. They appear to fill up and detach, fusing to become the apical MVBs.
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  • 97
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    Journal of Morphology 128 (1969), S. 1-33 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Submandibular glands of the opossum have been studied by light and electron microscopy and compared with other mammalian salivary glands. The glands have four parenchymal segments which connect in the order named below to convey saliva toward the oral cavity. 1Secretory units are elongated branching tubules exhibiting mucous and special serous cell types. Mucous cells predominate and resemble those in other salivary glands. Special serous cells differ from “typical” serous cells. They contain a preponderance of tubular or vesicular endoplasmic reticulum and secretory granules which vary from electron lucent to electron opaque.2Intercalated ducts are short segments lined by nonsecretory, cuboidal cells.3Striated ducts are numerous and lie in the center of the lobule. The duct epithelium has four cell types, designated light cells, dark cells, Type I basal cells, and Type II basal cells. Light cells possess basal infoldings associated with mitochondria, but the other cell types lack this characteristic.4Excretory ducts are also lined by four cell types which bear the same names as those of striated ducts. Three of the four cell types are virtually identical to those of striated ducts, but light cells differ. They do not always contain basal infoldings and the supranuclear cytoplasm lacks distinct inner and outer zones.The glands resemble salivary glands of higher mammals in many respects while possessing certain unique cytological features which may reflect the secretory needs of the organism.
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  • 98
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    Journal of Morphology 128 (1969), S. 95-112 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several biological distances based on cranial and mandibular variation among breeding groups of white-tailed deer were calculated and compared with geographic distances among the groups. Distances based on epigenetic variation among ten groups were calculated using 16 non-metric variants of the cranium and mandible. Penrose's size and shape distances and Mahalanobis' D2 distance were calculated for 11 groups; the calculations were based on seven skeletal and seven dental metric variables of the mandible.The biological distances were correlated with geographic distance as follows: the epigenetic distance, 0.74; Penrose's shape distance, 0.71; Penrose's size distance, 0.45; and Mahalanobis' distance, 0.37. All correlations were significant at the 0.01 level. The epigenetic and Penrose shape correlations were significantly higher than the Mahalanobis correlation.Because of the conditions under which the breeding groups were selected, it was assumed that genetic affinites among the groups would be a function of geographic distance. The results suggest that the epigenetic distance and Penrose's shape distance reflect genetic affinities among groups better than do the Penrose size and Mahalanobis distances.
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  • 99
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    Journal of Morphology 128 (1969), S. 195-227 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism of lung ventilation in chelonians has been much debated. Electromyographic studies show that the basic mechanism in the snapping turtle, Chelydra serpentina, is dependent on the activities of four major respiratory muscles that are capable of varying the volume of the visceral cavity. The precise mechanism utilized varies in response to environmental factors, especially the depth to which the animal is submerged. Chelydra tends to reduce muscular activity to a minimum, and hydrostatic pressure or gravity replaces muscular effort whenever possible. The response is subject to hysteresis. Both the mechanics and pattern of ventilation in Chelydra differ from those of Testudo. The differences appear to be attributable in part to Chelydra's markedly reduced plastron and more extensive respiratory musculature and in part to the different habitats occupied by the two species.
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  • 100
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The purported “neoblasts” of the serpulid Spirorbis have been studied in Spirorbis (Paradexiospira) vitreus and Spirorbis (Laeospira) borealis at both the light and electron microscopic levels. These perivasal cells occur in greatest abundance around the ventral blood vessel of the achaetous region. In light microscope preparations, the perivasal cells are intensely basophilic, containing basally situated nuclei, and relatively large nucleoli. The fine structure of the perivasal cells reveals that they contain an abundance of rough endoplasmic reticulum, well-developed Golgi complex, heterogeneous dense bodies, and cytolysomes. The respiratory pigment chlorocruorin, which has a diameter of about 230 Å and is believed to be composed of two superimposed hexagonal components, has been localized within: cisternae of the rough endoplasmic reticulum, elements of the Golgi complex, and membrane-bounded vesicles at the base of the perivasal cells. Evidence is advanced which strongly suggests that molecules of chlorocruorin are transported from the perivasal cells into the lumen of the vessel by reverse pinocytosis. It is concluded that whatever other functional role(s) the perivasal cells of Spirorbis may have, a major function is the synthesis and secretion of chlorocruorin. Whether the perivasal cells can be considered to be pluripotent is discussed.
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