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  • Cell & Developmental Biology  (479)
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  • METEOROLOGY AND CLIMATOLOGY  (347)
  • 1980-1984  (1,226)
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  • 1981  (1,226)
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  • 1925  (29)
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  • 1965-1969
  • 1960-1964
  • 1925-1929  (60)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 517-557 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An early segregation of germ cells and migration through a germ track into the gonad does not occur in the albino rat. The germ cells are produced only from the peritoneum of the genital region and their earliest formation is coincident with the thickening of the coelomic epithelium to form the genital ridge. This takes place eleven days after insemination in embryos of approximately 18 somites. Germ cells continue to form from the peritoneum during the early development of the gonad. The peritoneum of this region also produces mesenchyme, smaller cells of the gonads, and the germinal epithelium.The argument for the specific character of the germ cells in vertebrates and their continuity from the egg is based largely upon assumption, and not upon substantial observations, and must be discarded. Germ-cell origin is a problem of cellular differentiatio, and not of early segregation.
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  • 3
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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
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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
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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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  • 7
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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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  • 8
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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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  • 9
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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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  • 10
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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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  • 11
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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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  • 12
    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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  • 13
    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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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1925), S. 239-265 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reports experiments with Fundulus heteroclitus to modify larval development by means of ultraviolet radiation. Eggs were exposed to radiation at various intervals after fertilization for varying periods of time. The results accord with previous work on fish teratology, and the developmental types obtained are essentially similar to those produced by chemicals, cold, and hybridization. The deviations from normal development occur in the same body regions as do those in other vertebrates whose early development has been modified by the action of radiation (x-rays, radium, etc.).The results of these experiments indicate that there is a non-specificity in susceptibility relations with the production of similar types of monsters for widely different reagents. That these eggs are differentially susceptible to the action of ultraviolet radiation is indicated by the fact that those regions which have the highest metabolic activity when an inhibiting influence is active are the ones most generally affected. Thus modifications of the nervous system, sense organs, circulatory system, tail region, and body axis result, respectively, in the production of varying degrees of cyclopia, inadequate circulation, short, stubby or bent, non-motile tails (some bifid), and anterior twinning.As these modifications may be produced by applying inhibiting influences during the first few minutes after fertilization, it is evident that there is in the egg at this stage some constitutional or physiological basis which determines early differences in susceptibility of its various parts.
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  • 15
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    Journal of Morphology 167 (1981), S. 35-42 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vasculogenesis of the bursa cloacalis (bursa of Fabricius) was examined in 10- to 21-day chick embryos and in chicks during the first 5 days post-hatching. The entire circulatory system was injected with India ink, and the bursae were then removed and either cleared for examination in toto or sectioned serially. The bursa was supplied by three pairs of extrinsic blood vessels. At 10 and 11 days of incubation, most intrinsic vessels were arranged in a superficial, hexagonal network. In regions of developing plicae, the hexagonal plexus extended into the core of each plica, forming middle plical vessels. The latter were interconnected across interplical areas by cross-connecting vessels. The middle plical vessels gave rise to small capillary offshoots, which soon increased in complexity, forming delicate loops. Branches extended from these loops through the subepithelial lamina propria to incipient epithelial buds by 12 days of incubation. All epithelial buds were supplied by at least one such branch, and similar branches extended to the basal aspect of the epithelium in areas where epithelial buds had not yet formed. This observation is consistent with the hypothesis that blood vessels induce formation of epithelial buds. At about 15 days of incubation, the cortex and medulla of each developing lymphatic follicle were defined clearly, and an intricate, web-like, capillary network coursed throughout the follicular cortex. The medulla appeared to be devoid of capillaries. The diameters of all intrinsic and extrinsic bursal blood vessels gradually increased throughout development. During post-hatching stages, the diameters of the extrinsic vessels continued to increase, whereas those of the intrinsic vessels were markedly decreased from late pre-hatching stages.
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  • 16
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    Journal of Morphology 167 (1981), S. 103-108 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The use of hormone replacement to support limb regeneration in hypophysectomized newts has been the subject of many investigations. Growth hormone, as well as prolactin (PL) in combination with exogenously supplied thyroxine, have all been shown to he effective. However, the bovine growth hormone used to support limb regeneration was contaminated by prolactin and thyroidstimulating hormone (TSH). The present investigation evaluates the significance of (1) prolactin contamination and (2) endogenous thyroxine synthesis resulting from TSH contamination on limb regeneration in hypophysectomized newts. The effect of supplying exogenous thyroxine was also evaluated. Our studies showed that when hypophysectomized newts were injected with contamination levels of PL and TSH, regeneration occurred, suggesting that the newt's thyroid synthesized sufficient thyroxine to support a prolactin-thyroxine synergism. The endogenous thyroxine was synthesized by thyroid glands that were indistinguishable from those of saline-injected, hypophysectomized controls.
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  • 17
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    Journal of Morphology 167 (1981), S. 109-118 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β-gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot-pad, shows a pattern of histogenesis directly comparable to that of β-glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis.
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  • 18
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    Journal of Morphology 167 (1981), S. 167-184 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: There are four major tooth attachment modes in actinopterygians. Type 1 mode is characterized by complete ankylosis of the tooth to the attachment bone; it is the primitive attachment mode for actinopterygians. In Type 2 mode there is a ring of collagen between the tooth base and the bone. In Type 3 mode mineralization extends near or to the bone at the anterior tooth border, and there is a relatively large collagen area on the posterior surface of the tooth; Type 3 teeth are hinged with an anterior axis of rotation. Type 4 teeth also have a relatively large posterior collagen area, but there is no collagenous connection between the anterior basal tooth border and the attachment bone; Type 4 teeth are hinged, with a posterior axis of rotation. Types 2, 3, and 4 attachment modes appear to result from retardation of mineralization and resemble, with some modifications, ontogenetic stages in the development of Type 1 mode; they are considered to be paedomorphic features. Attachment modes 2, 3, and 4 are each associated with a major evolutionary lineage within the Teleostei. The degree to which paedomorphosis has been a factor in teleostean evolution is discussed.
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  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bolitoglossa occidentalis, a lowland salamander of Mexico and Guatemala, has a highly derived morphology. The features that are derived with respect to the condition in generalized members of the genus include the following: (1) small body size; (2) short tail; (3) fully webbed hands and feet; (4) reduction and loss of certain phalangeal elements; (5) fusion of carpals and tarsals; (6) absence of prefrontal bones; and (7) reduced skull ossification. The ontogeny of this species was analyzed quantitatively and compared with the patterns of growth and differentiation encountered in two morphologically generalized members of the genus, B. rostrata and B. subpalmata. Most of the derived features can be explained by invoking a single heterochronic process: truncation of development at a small size (most likely the product of early maturation). Therefore, B. occidentalis is a paedomorphic species whose morphology has been attained through the process of progenesis. This result supports Alberch's ('80a) prediction, based on functional analysis, that the principle adaptation to arboreality in B. occidentalis is small size; other derived morphological features are associated with the organism's truncated development and may have no adaptive significance. However, patterns of dissociation are found within this overall progenetic process. Some of these include the following: (1) accelerated growth rates of the metatarsals and first phalanges, and retarded growth rates of the second and third phalangeal elements; (2) dissociation between rates of ossification of the skull and the autopodial elements; and (3) dissociation between the timing of termination of the process of shape change during the ontogeny of the foot (the product of differential growth between digital and interdigital areas) and termination of growth in overall foot size (foot surface area). This later result illustrates the independence of morphogenetic phenomena (shape change) from processes of growth (size increase).
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  • 20
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A table of development (25 stages) for the period of incubation in the pouch was constructed for Gastrotheca riobambae; it can be used to stage embryos of other egg-brooding hylids. Analysis of embryonic weights during incubation shows that the mother does not contribute nutrients, but gases and other factors are probably exchanged between mother and embryos.According to species, incubation on the back of the mother is carried to the froglet or to the tadpole stages. Development in these hylids is characterized by specialized gills, the bell gills derived from the branchial arches. In some species, the bell gills derive from the first branchial arch and cover less than 50% of the embryo, while in others, the bell gills come from both branchial arches I and II and cover from less than 50% to 100% of the embryo. The most complex bell gills derive from the fusion of the two branchial arches.The majority of egg-brooding hylids live in tropical forests and carry development to the froglet stage. Tadpoles are produced by species of Flectonotus, Fritziana, and Gastrotheca. Tadpole-producing species of Gastrotheca have the most complex reproductive adaptations among egg-brooding hylids Acceleration and retardation in development seem to have played important roles in the evolution of these frogs. The evolutionary trend has been toward direct development, i.e., disappearance of the free-living larval stages through maternal incubation, and later to a recovery of the free-living tadpole stages in species of Gastrotheca with the most complex reproductive adaptations.
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  • 21
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    Journal of Morphology 167 (1981), S. 313-331 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ectodermal eyes, 45-55 μm in diameter, of the cnidarian hydrozoan Cladonema radiatum Dujardin possess a lens approximately 15 μm in diameter enveloped by an eyecup (retina). An overlying layer of intensely vacuolated distal process of the adjoining epithelial cells forms a transparent cornea. The eyecup is composed of three cell types: basal cells, melanin-containing pigment cells, and photoreceptor cells. The last two cell types occur in the ratio of approximately 2:1. Histogenesis of the eye both during ontogeny and regeneration is described from light and electron microscopic investigations. During ontogeny the cell types forming the retina are derived from a compact group of morphologically undifferentiated cells, but during regeneration a primordium is formed by regeneration cells. In both cases the lens is built from distal nonnucleated cytoplasmic portions pinched off from the pigment cells. The cornea is formed by distal lamellar processes of the ocellus adjoining the epithelial cells. Through EM-histochemical methods (silver impregnation and DOPA-oxidase reaction) the pigment of the chromatophores of the retina was identified as melanin.
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  • 22
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    Journal of Morphology 168 (1981), S. 247-247 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 23
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    Journal of Morphology 168 (1981) 
    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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  • 24
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    Journal of Morphology 168 (1981), S. 189-227 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The neural organization of the olfactory system in the desert iguana, Dipsosaurus dorsalis, has been investigated by using the Fink-Heimer technique to trace the efferents of the main and accessory olfactory bulbs, and Golgi preparations to determine the spatial relations between olfactory afferents and neurons in the primary olfactory centers.The accessory olfactory bulb projects to the ipsilateral nucleus sphericus via the accessory olfactory tract. The main olfactory bulb projects to the ipsilateral telen-cephalon via four tracts. The medial olfactory tract projects to the rostral continuation of medial cortex and to the septum. The intermediate olfactory tract projects to the olfactory tubercle and retrobulbar formation. The lateral olfactory tract projects to the rostral part of lateral cortex. The intermediate and lateral olfactory tracts also merge caudally to form the stria medullaris, which crosses the midline in the habenular commissure and distributes fibers to the contralateral hemisphere via two tracts. The lateral corticohabenular tract terminates in the contralateral lateral cortex. The anterior olfactohabenular tract terminates in the contralateral olfactory tubercle, retrobulbar formation and septum.The relation of olfactory afferents to neurons in the medial cortex, lateral cortex, nucleus sphericus, and septum corresponds to a pattern of organization that is typical of many olfactorecipient structures. Such structures are trilaminar, with neurons whose somata are situated in the intermediate layer (layer 2) sending spine-laden dendrites into an outer, molecular layer (layer 1). Olfactory afferents intersect the distal segments of these dendrites. By contrast, other olfactorecipient structures in Dipsoaurus deviate from the familiar pattern. Olfactory afferents intersect somata lying in layer 2 of the retrobulbar formation. Olfactory afferents include some fibers which course perpendicularly to the surface of the olfactory tubercle and extend deep to layer 2.
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  • 25
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    Journal of Morphology 168 (1981), S. 281-288 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microscopic examination of adipocytes isolated from adult rat epididymal adipose tissue revealed numerous small cells (〈 10 μm) morphologically similar to larger adipocytes. These small adipocytes appear identical to a new classification of adipose cells termed preadipocytes. Electron micrographs of these preadipocytes revealed examples of cells 〈 10 μm in diameter in various stages of maturation and lipid accumulation. The percent distribution pattern of these small adipocytes was not significantly altered by exercise although exercise shifted the distribution patterns of the larger cells (〉 30 μm) toward a smaller mean cell size. The quantitative significance of preadipocytes is not established but these preliminary observations indicate that adipocytes 〈 10 μm in diameter may account for a numerically greater proportion of the total adipocytes observed in collagenase isolated preparations than heretofore recognized, although their contribution to total adipose mass is probably negligible.
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  • 26
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When a newt is hypophysectomized prior to or at the time of forelimb amputation a dermal barrier eventually forms between the apical cap of epithelium and the underlying mesenchymal tissues, and the typical regeneration response is transformed to a wound-healing morphology. When hypophysectomized newts are injected on continuous alternate days beginning either at the time of amputation or following a fifteen-day delay, with either growth hormone (GH) or prolactin in combination with thyroxine (PLT4), normal regeneration occurs. Our experiment was designed to examine critically the early changes occurring in apical connective tissue that had been allowed to form as a consequence of hypophysectomy prior to forelimb amputation. Adult newts were hypophysectomized and five days later both forelimbs were amputated distal to the elbow. Following a delay of eight days, to permit the formation of connective tissue beneath the apical epithelium, they were injected intraperitoneally on successive alternate days with GH or with PL in combination with T4 in the aquarium water. The apical connective tissue of the limb stumps underwent a progressive erosion and became discontinuous by day 4. The limb morphology of hypophysectomized newts receiving ACTH or PL or maintained in thyroxine was virtually identical to sham-injected hypophysectomized controls. It appears that an initial effect of GH or PLT4 therapy is to establish the epithelial-mesenchymal interface that previously has been suggested to be a requisite for the regenerative event.
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  • 27
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The external features of the embryo and the first instar larva of Pedetontus unimaculatus are described. Blastokinesis of P. unimaculatus is very similar to that of Petrobius brevistylis (Larink, '69), but differs from that of Machilis alternata (Heymons and Heymons, '05). The superficial structures of three pairs of protocerebral lobes are present. The terga of the mandibular, maxillary, and labial segments take part in the formation of the head capsule. In the maxilla and labium, the palpi are homologous with the telopodites of the legs; the other parts proximal to the palpi are homologous with the coxopodites. No sternal element contributes to the postmentum. Both glossa and paraglossa consist of two lobes. The pleuropodium, stylus and ventral sac are derived from distal parts of appendage anlagen. The pleuropodium of the first abdominal segment is homologous with the styli of the successive abdominal segments; the ventral sacs of succeeding segments are serially homologous. The basal parts of appendage anlagen cover each sternum in the first to ninth abdominal segments to form coxites, which are therefore appendicular in origin. The basal part of the cercus also covers the ventral and lateral surfaces of the eleventh abdominal segment.
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  • 28
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    Notes: The micropterygid moth Neomicropteryx nipponensis belongs to the most primitive suborder Zeugloptera of the Lepidoptera. During embryogenesis the small circular germ disk formed on the ventral egg surface invaginates deeply into the yolk. It finally separates from the egg periphery or rudimentary serosa, and becomes a sac-shaped germ rudiment. Its anterior part later develops into the germ band, while its posterior part is the future amnion. Just before revolution of the embryo, the embryo assumes a completely superficial position beneath the yolk. Neither amnion nor serosa rupture during revolution; by completion of dorsal closure they have been incorporated into the yolk to form the secondary dorsal organ.The formation of the germ rudiment and embryonic membranes in N. nipponensis resembles those of swift moths, Endoclyta (suborder Monotrysia) and of the caddisflies, Stenopsyche (Trichoptera), but differs from those of ditrysian Lepidoptera. The secondary dorsal organ has never been found in any other lepidopteran embryos; however, it is formed in N. nipponensis and in the Trichoptera. The results of the present study strongly support the general phylogenetic views that the Zeugloptera have a close affinity to the Trichoptera.
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  • 29
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    Journal of Morphology 169 (1981) 
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  • 30
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    Journal of Morphology 169 (1981), S. 29-47 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning and transmission electron microscopic observations were made on the rattlesnake lung, which has the form of a cigar-shaped bag enclosing a large axial air chamber. The lungs were fixed by tracheal instillation of fixative to preserve the structural features of inflated lungs. An open tracheal groove along the ventral aspect of the lung is the only structural “airway” present. The wall of the lung has two histologically distinct regions: anteriorly, a respiratory portion, where up to three generations of septa subdivide the wall into cup-shaped gas-exchange chambers, termed faveoli; and posteriorly, a simple, thin-walled saccular portion. The epithelium lining the internal surface of the lung is composed of several cell types: (1) ciliated cells; (2) type I pneumonocytes; (3) type II pneumonocytes, secretory cells characterized by the presence of lamellar bodies; and (4) serous epithelial cells, secretory cells characterized by the presence of homogeneous, densely staining secretory granules. However, the distinctiveness of the secretory cell types in the snake lung is blurred because intermediate-appearing cells have both the lamellar body and homogenous type of secretory granule. The nonepithelial components of the pulmonary wall and septa consist of blood vessels and lymphatics, smooth muscle cells and fibroblasts, embedded in a matrix of extracellular connective tissue fibers. Tubular myelin figures were observed in the faveolar lining layer.
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    Journal of Morphology 169 (1981), S. 91-111 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Autoradiographic, HRP, and Fink-Heimer techniques define olfactory bulb efferents in the channel catfish. The olfactory bulb projects bilaterally to eight targets in the area ventralis telencephali including the preoptic area, five targets in area dorsalis telencephali, and the posterior tuber of the diencephalon. There is additional input to the peripheral margin of the internal cell layer of the contralateral olfactory bulb. Fibers cross in rostral (nervus terminalis and commissure of Goldstein) and caudal components of the anterior commissure and the habenular commissure. HRP techniques reveal the origin of bulb efferents from the internal and mitral cell layers of the olfactory bulb. The olfactory tract is divided into five major components, each with a unique subset of ipsilateral and commissural pathways.
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  • 32
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    Journal of Morphology 169 (1981), S. 149-159 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anuran (Rana) and urodele (Ambystoma) amphibian eggs were subjected to prolonged unnatural orientations in relation to gravity. In some cases eggs were rotated 90°, while in other instances eggs were rotated 180° (complete inversion). Alterations in the pigmentation pattern, cleavage pattern, and site of involution were observed. Despite these unnatural orientations to gravity, the morphogenesis of axial structures was frequently normal. Reorganization of the egg cytoplasm apparently takes place after the unnatural orientation. Rather than being localized in a fixed position in the egg (e.g., the egg cortex), the determinants for the pattern of early embryogenesis are probably located in that portion of the cytoplasm (e.g., “internal” cytoplasm) that orients to gravity.
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  • 33
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    Journal of Morphology 169 (1981), S. 207-223 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoarchitecture and neuronal morphology of the torus semicircularis in the red-eared turtle, Chrysemys scripta elegans, were examined in Nissl-stained and Golgi-impregnated material. The torus semicircularis begins in the caudodorsal mesencephalon and extends rostrally and laterally to end ventrally to the tectal ventricle. The torus semicircularis consists of a central nucleus and a laminar nucleus, which is interposed between the central nucleus and the ventricle.The central nucleus can be divided into two regions, a small, large-celled area, located dorsally, and a larger area of small spherical (6-17 μm), large spherical (18-25 μm), triangular (15-27 μm) and fusiform (10-26 μm) neurons. The small spherical cells have two dendritic patterns: “radiate” and “single.” The radiate pattern has a dorsoventral orientation, several secondary branches and few dendritic spines. These cells are usually located in the center of the central nucleus. The single pattern is oriented mediolaterally. This cell type is most often observed at the periphery of the central nucleus. These neurons have few secondary branches and dendritic spines. The large spherical neurons display two dendritic orientations: dorsoventral and mediolateral. All dendritic trees have numerous secondary branches and few dendritic spines. The triangular neurons exhibit primary dendrites projecting from the corners of the somata and have few secondary branches and dendritic spines.The fusiform neurons have a majority of their dendrites oriented mediolaterally, few secondary branches and a small number of dendritic spines.The laminar nucleus consists of several layers and three cell types: ovoid (9-15 μm), triangular (20-40 μm), and fusiform (20-40 μm). All neurons have few secondary dendritic branches and few dendritic spines. The dendrites of many neurons course perpendicularly to the long axis of the brainstem and encapsulate the central nucleus. Some ovoid and fusiform neurons display dendrites that enter the central nucleus.
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  • 34
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    Journal of Morphology 170 (1981), S. 113-131 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the foregut muscles of five spider families (Theraphosidae, Agelenidae, Araneidae, Lycosidae, Salticidae) was described, and the individual fibre numbers and fibre cross diameters of the muscles were determined. The nomenclature of these muscles was reviewed and modified if necessary.Oxidative enzyme and myosin-ATPase histochemistry revealed eight dilatatory muscles of the foregut to consist of slow (type I) fibres, while fast fibres (type IIB), and intermediate fibres, were only to be found in the two other muscles of the foregut, and in the remaining prosomal muscles (type IIA fibres around the poison gland).The eight sucking muscles proper of the foregut also showed stronger activities of transmitter metabolizing enzymes [monoamine oxidase, glutamate dehydrogenase(NAD)], and comparatively distinct amounts of glycogen and lipids.
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  • 35
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    Journal of Morphology 169 (1981), S. 325-336 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reports observations on the innervation of gill filaments of the lamprey, Lampetra japonica. Nerve fibers run on each side of the afferent filament artery (AFA nerve) and in the connective tissue compartment along the efferent filament artery (EFA nerve). The AFA nerve supplies vasomotor fibers to the afferent filament artery and arteriovenous anastomoses and special visceral motor fibers to branchial muscle fibers (musculus compressor branchialis circularis). Nerve endings of the vasomotor fibers contain large, cored vesicles (60-180 nm in diameter) with a variable number of small, clear vesicles (30-70 μm in diameter), whereas those of the visceral motor fibers have many small, clear vesicles with few large, cored vesicles. The EFA nerve supplies vasomotor fibers to the efferent filament artery. Their endings, containing mixtures of predominantly large, cored vesicles and small, clear vesicles make close synaptic contacts with reticular cells. The latter in turn are connected with each other or with smooth muscle cells in the wall of the efferent filament artery by nexuses. No nerves are found in the axial plate between the afferent and efferent filament arteries nor in the secondary lamellae of individual gill filaments. No afferent nerve supply to the gill filament has been found.
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  • 36
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    Journal of Morphology 169 (1981), S. 351-355 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study, using the cobalt chloride technique, clarifies the origin of the giant axons in the cockroach, Periplaneta. Each giant axon in the ventral nerve cord arises from a single cell body located in the sixth abdominal ganglion. The position of the soma is always contralateral to the giant axon; it projects anteriorly. In six giant neurons, the axonic and dendritic branches are ipsilateral while the somata are contralateral. In two neurons, both the soma and the dendritic branches are ipsilateral while the axons are contralateral. The dendritic arborizations of the giant neurons form a dense and compact mass of neuropile in each half of the posterior and middorsal part of the ganglion where sensory fibers, primarily from the cercal nerves terminate. The relation of these findings to earlier electrophysiological studies is discussed.
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  • 37
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    Journal of Morphology 170 (1981) 
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  • 38
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    Journal of Morphology 168 (1981), S. 309-319 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Untreated adult newts do not undergo normal limb regeneration following hypohysectomy. A fibrocellular dermal barrier (cicatrix) atypically forms between the apical epithelium and the underlying mesenchymal tissues. Historically, continuous administration of growth hormone or of prolactin in combination with thyroxine restored regenerative capacity to these newts. In a previous investigation, we demonstrated that the initial effect of these two hormone treatments, when administered on alternate days to hypophysectomized newts beginning eight days post-amputation, was to facilitate the erosion of the fibrocellular barrier and establish the epithelial mesenchymal interface that is observed in a regenerating limb.The present investigation was designed to evaluate the necessity of continuous hormone therapy to maintain limb regeneration in hypophysectomized newts. One, two, or three injections of growth hormone or of prolactin in combination with thyroxine was administered on successive alternate days to hypophysectomized newts either immediately following limb amputation (ID) or beginning eight days post-amputation (DD). The ID and DD newts receiving one, two, or three injections of growth hormone showed evidence of regeneration to the digitiform stage by day 30 post-amputation, while those receiving prolactin and thyroxine underwent wound healing. While both hormone treatments initially promoted a dermis-free apical epithelium, only hypophysectomized newts that had received growth hormone were able to continue regenerating.We have, therefore, concluded that discontinuous growth hormone therapy is sufficient to initiate and maintain the conducive environment for limb regeneration to advanced stages in the hypophysectomized newt. While initiating this process, prolactin and thyroxine therapy on a discontinuous regime does not maintain regeneration. The direct and indirect role of growth hormone in supporting limb regeneration in normal and hypophysectomized newts is discussed.
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  • 39
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    Journal of Morphology 170 (1981) 
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  • 40
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    Journal of Morphology 169 (1981), S. 71-90 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoarchitectonics of the telencephalon of the channel catfish, Ictalurus punctatus, are described as a basis for experimental analysis of telencephalic afferents and efferents. The olfactory bulb comprises: (1) an outer layer of olfactory nerve fibers, (2) a glomerular layer, (3) an external cell layer, (4) an inner fiber layer, and (5) an internal cell layer. The telencephalic hemispheres comprise the areas ventralis and dorsalis telencephali. The area ventralis consists of: (1) a precommissural, periventricular zone including nucleus 'nother (Vn), the ventral nucleus (Vv), and the dorsal nucleus (Vd); (2) a precommissural, migrated zone of central (Vc) and lateral (VI) nuclei; (3) a supracommissural nucleus (Vs); (4) a caudal commissural zone of postcommissural (Vp) and intermediate (Vi) nuclei; and (5) a preoptic area (PP). The area dorsalis comprises: (1) medial (DM), (2) dorsal (Dd), (3) lateral [DL, containing dorsal (DLd), ventral (DLv), and posterior (DLp) regions], (4) posterior (DP), and (5) central (DC-1, -2, -3) areas. Nucleus taeniae (NT) is transitional between areas dorsalis and ventralis.
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  • 41
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    Journal of Morphology 169 (1981), S. 61-70 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the newly hatched larva of Carcinonemertes epialti Coe has been examined by light and electron microscopy. The newly hatched larva is covered with cilia and measures about 110 μm in length. Four types of epidermal cells are recognizable: (1) Multiciliated cells, (2) vacuolated cells, (3) mucous cells, and (4) “knob cells”. The knob cells protrude from the posterior end of the larva and contain granules and bundles of microfilaments. The gut is incomplete and is located ventral to the bipartite proboscis. A bilobed brain and two subepidermal ocelli are found in the anterior end of the larva. The anterior and posterior cirri are composed of long, tightly appressed cilia that arise from an invagination of the epidermis at each end of the larva. The anterior cirrus is surrounded by two types of glandular cells. It is proposed that the knob cells have a role in larval attachment, combining the functions of the adhesive cells and anchor cells described in the duo-gland system of turbellarians. The cirri are believed to be larval sensory structures that function in substrate selection. Histological and ultrastructural observations suggest that the larvae of Carcinonemertes are relatively long lived and develop into juveniles without a drastic metamorphosis.
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  • 42
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    Journal of Morphology 169 (1981), S. 141-148 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glycoproteins are present in the web of the orb-weaving spiders Argiope trifasciata and Argiope aurantia. Periodic acid-Schriff reactive glyco-proteins are confined in large part, to the sticky spiral and sticky spiral-radial junctions. Glycoproteins containing amino sugars appear associated with all fibers, especially the radial fibers. Enzymes may be used to remove glycoproteins selectively from the sticky spiral and stabilimentum.
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  • 43
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    Journal of Morphology 169 (1981), S. 191-206 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pineal organ of Ensatina eschscholtzi, a terrestrial and secretive species of salamander of the family Plethodontidae, is a photoreceptive structure lying on the dorsal surface of the diencephalon. The pineal is flattened with a broad lumen and consists of three cell types: photoreceptors, supportive cells, and neurons. Pineal photoreceptors are typical vertebrate photoreceptors and possess outer segment formations which, however, are frequently contorted and disorganized. Sloughing of apical portions of outer segments and vesiculation along the lateral edges of outer segment membrane disks are consistently observed and presumed to represent mechanisms of outer segment membrane recycling. Photoreceptors have basal processes which synapse with neural dendrites. Synapses between photoreceptor basal processes are occasionally observed. All synapses are characterized by synaptic ribbon structures of variable number, size, and configuration. Dense-core vesicles are occasionally observed mingled with clear synaptic vesicles within photoreceptor basal processes. Supportive cells within the pineal function in phagocytosis and recycling of shed outer segment membrane material, and neurons are localized at the lateral margins of the organ. The latter send axons into the ipsilateral side of the dorsal diencephalon. The pineal organ of Ensatina shows marked variation in overall size (cell total), cell type proportions, absolute neuron number, and ratio of photoreceptor number to neuron number for individual pineals. None of these morphological parameters is correlated with body size, sex, or season, and it is assumed that such variability represents significant variation in photosensory capabilities. It is suggested that the pineal organ of Ensatina is a partially degenerate photoreceptive structure.
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    Journal of Morphology 169 (1981) 
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  • 45
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    Notes: In order to investigate quantitatively and objectively the influence of the normal microbial flora on the ultrastructure of the alveolar macrophage, three groups of mice were studied stereologically: germ-free (GF), conventionally reared under non sterile isolation conditions (IC), and conventionally reared in an open environment (OC). The alveolar macrophages of GF mice possess a smaller mitochondrial compartment, possibly with fewer organelles, than the macrophages of conventional mice. Other influences of the normal microflora on alveolar macrophage substructure are obscured by the effects of nonmicrobial stimuli such as droplets of lung surfactant.No previous comparison exists of alveolar and peritoneal macrophage ultrastructure. Lung macrophages are larger than the phagocytes of the peritoneum, but the difference in size is much less than is commonly believed. Alveolar macrophages are rounder than peritoneal macrophages, and exhibit much less rough endoplasmic reticulum (RER) as well as differences in mitochondrial morphometry. No difference in mitochondrial volume fraction exists between the two types of macrophage even though alveolar macrophages represent the extreme of aerobic adaptation in the mononuclear phagocyte system. Phagosomes occupy a significant fraction of cellular volume only in the alveolar macrophages. Moreover alveolar phagocytes contain fewer but larger lysosome-like granules than are found in peritoneal macrophages. The results represent the first objective, quantitative structural evidence confirming the common belief that alveolar macrophages experience greater physiological stimulation than peritoneal macrophages. The normal microflora accounts for only a small proportion of the differing degree of stimulation exerted on the two types of macrophage.
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  • 46
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    Notes: In this work, we have completed a study of the development of the ovoviviparous lizard Liolaemus tenuis tenuis. Ovoviviparity in this lizard is a condition in which eggs are retained within the reproductive duct for about 60 days. During this period the phases of segmentation, gastrulation, neurulation, presomitic, and somitic embryos transpire. During the months of December and January the eggs are laid, and at this time the embryos are comparable to stage 27 Liolaemus gravenhorsti lizard embryos, or to stage 29 Calotes versicolor lizard embryos. Differentiation of the facial region occurs between Days 12 and 42 after egg laying. Limbs develop rapidly between the 8th and 23rd days. By 53 days the appendicular skeleton is completely formed. After 36 days the mesonephros begins to degenerate, and its function is gradually taken over by the developing metanephros. Newborn lizards do not possess an egg caruncle. During the period up to hatching, there is a great increase of liquid within the egg, presumably amniotic fluid. Cracks develop in the leathery shell shortly before hatching and are, perhaps, the first sign of the onset of hatching. Increase of liquid in the egg during postlaying development accounts for its increase in weight and change in shape. Weight of the embryo at hatching does not exceed 32% of the total weight of the egg.
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  • 47
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    Journal of Morphology 170 (1981), S. 1-27 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The coronary arterial supply and associated structures have been examined and described for 29 species covering 11 reptilian families, with supplementary observations on other species. Variation in the origin, number, and configuration of coronary arterial vessels is mainly interfamilial and the same is true regarding the presence or absence of a gubernaculum cordis. It is suggested that the presence of a hitherto unrecognized intertruncal branch of the coronary artery has been responsible for much of the alleged intrafamilial variation reported in earlier literature. A general review of the cardiac blood supply and coronary arterial supply of other lower vertebrates is presented and used as a basis for interpreting phyletic and functional aspects of the reptilian conditions.
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  • 48
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The enameloid and dentine of Squalus acanthius have been compared histochemically with those of Bos taurus. Squalus enameloid is much less reactive to a variety of stains or reagents than dentine or bovine immature enamel but it does have positive reactions with picromethyl blue, Mallory's and Van Gieson's stains, and Alcian blue. It stains faintly with Biebrich scarlet, indicating some anionic groups. Specific reactions for tyrosine, tryptophane, lysine, histidine, arginine, and cysteine are negative. Bos immature enamel is positive for cationic, anionic, and aromatic reactive groups by all test procedures, and dentine was positive for the anionic components. Bovine maturing enamel, however, is more similar in terms of lack of reactivity to Squalus enameloid but differed because the bovine enamel was moderately positive for tyrosine; tryptophane, and anionic groups and negative with Mallory's picromethyl blue and Van Gieson's stains. A fibrous transitional area between Squalus dentine and enameloid has staining reactions characteristic of both collagen and keratins.
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  • 49
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    Journal of Morphology 170 (1981), S. 181-194 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five concentrations of nitrogen mustard (methyl-bis-chlorethylamine) have been administrated to different stages of development of trout embryos (Salmo gairdneri), in order to study their effect on the formation of both pelvic fins soft tissue and skeleton. Sensitivity of epidermis and mesoderm toward this cytotoxic agent has been assessed histologically. Although both components are sensitive to nitrogen mustard, mesoderm is more sensitive than epidermis. These results are compared with the results of similar studies on tetrapod limb buds. The pelvic fin skeleton of some treated animals was doubly stained in toto for cartilage and bone by Alcian blue and alizarin, followed by clearing. Other specimens were processed for histological serial sections. Analysis included comparison of the following parameters: (1) dose of nitrogen mustard, (2) stage of fin bud development at the time of treatment, (3) importance of necrosis in the fin bud, and (4) abnormalities of the endoskeleton of the fin (pelvic girdle and radials) and of the dermal skeleton (lepidotrichia and actinotrichia) one month after the hatching of control animals. Results suggest (1) that material of endoskeleton and lepidotrichia are laid down simultaneously, and (2) that differentiation of actinotrichia is independent of differentiation in endoskeleton and lepidotrichia.
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  • 50
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    Journal of Morphology 40 (1925), S. 261-297 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V-shaped leptotene threads are polarized with their apices embedded in one plasmosome-like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring-shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.
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  • 51
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The primordial germ cells of urodeles and anurans can occupy comparable positions in the embryo only in very early stages of development, if at all. When first recognizable as reproductive elements, their situation in the two amphibian orders is quite strikingly different.The germ cells first become recognizable in urodeles in the medial edge of the lateral mesoderm; there is no evidence that their position previous to this time is other than mesodermal. In the anura they are entodermal in association during early development; they are finally separated from the dorsal portion of the roof of the archenteron to form a single axial germ-cell cord. No amphibian species studied showed a mode of origin different from that characteristic of its order.The so-called migration of the amphibian germ cells to their definitive situation is interpreted as the result of growth shiftings of related parts. Germ cells do not migrate independently through the tissues. Aberrant or ectopic cells for the most part result from failures or faulty correlations of growth processes. Certain aberrant cells of the caudal portion of the body in urodeles indicate the inclusion of sex elements in the ventral as well as in the lateral mesoderm.
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  • 52
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    Notes: The musculature of the ophidian head is a fairly complex structure, due to the specialization of the skull and the peculiar movements and motions made possible by the high degree of streptostylism.This musculature has been derived from the lacertilian type by a splitting and a shifting of the original elemental muscle masses of this group. Most of the muscles are clearly homologous with those of the Lacertilia. Some cannot be homologized by a study of the mature forms.The greatest differences lie in the separation of the muscle masses in the ophidia, as compared with the undivided masses in the Lacertilia. Since the jaw movements of the Lacertilia are rather simple, there is no need for any subdivision or splitting of the jaw muscles, but with the complex movements of the ophidia this becomes necessary.A few of the ophidian muscles appear to be neomorphs, as no key to their origin could be determined by a comparison with lacertilians.
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  • 53
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    Journal of Morphology 40 (1925), S. 1-109 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Much more information than is available at present must be obtained before the phylogeny of the muscular system in the Teleostei can be worked out satisfactorily. As a step toward the solution of this problem, the present study gives a detailed description of twenty cranial muscles in a number of species belonging to three groups of cypriniform fishes: the Cyprinoids, Cobitoids, and Siluroids.Particular attention is given to the morphological relations of the following muscles: adductor mandibulae, geniohyoideus, levator arcus branchialis, adductor arcus palatini, retractor branchialis dorsalis, interarcualis dorsalis and the trapezius.Comparison is made between corresponding muscles in different members of the three groups of fishes, and various homologies are pointed out between muscles in cypriniform and those in other fishes, especially Amia, Scomber, Perca and Esox.
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  • 54
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    Journal of Morphology 44 (1927), S. 89-115 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The investigation is based upon hemal nodes of dog, man, and sheep. The material can be arranged in a regressive series leading from a typical lymph node, except for the occurrence of blood in parenchyma and sinuses, to a lymphoid structure at a late stage of involution. These structures uniformly lack lymphatics. There is no evidence of direct luminal connection between the blood-vascular supply and the sinuses. The observation that certain cervical and subcutaneous lymph nodes of the rabbit undergo a myeloid metaplasia following atrophy and disjunction of their lymphatics is used as an explanatory key of hemal nodes. According to our view, hemal nodes represent stages in the involution of transient lymph nodes. Disjunction of the lymphatics leaves the sinuses filled with entrapped lymphocytes. These differentiate into erythrocytes. These red blood cells may disintegrate and pass into solution or be removed either by giant cells or mononuclear phagocytes. Late stages in this process are represented by small irregular masses of lymphocytes, with wide sinuses practically free of blood.
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  • 55
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    Journal of Morphology 44 (1927), S. 217-264 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A description is given of the cytoplasmic alterations in the ovarian egg of Limulus polyphemus leading to the formation of yolk. The nucleolus is found to arise by the confluence of substance which passes from the cytosome into the nucleus, and it is suggested that the chondriosomes, and possibly also the dictyosomes, are derived from an excess of this substance which accumulates in the cytosome. Chondriosomes and dictyosomes are not present in the oogonia, but appear first in oocytes after the formation of the nucleolus is completed.During oogenesis the nucleolus is very active and the greater part of its substance is passed back to the cytosome. By the application of the method of Bell and Doisy for the determination of phosphate in body fluids, the nucleolus is found to be richer in phosphorus than are the other constituents of the cell. The nucleolar emissions effect the transport of phosphorus from the nucleus to the cytosome, where it is used in the synthesis of yolk. The definitive yolk arises by the interaction of nucleolar emissions, chondriosomes, dictyosomes, and ground cytoplasm.
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  • 56
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    Journal of Morphology 44 (1927), S. 341-361 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Conjugating individuals of Metopus sigmoides fuse at the anterior end, the pair presenting the appearance of an inverted letter U. The micronucleus of each conjugant by two successive divisions forms four micronuclei. Three of each four degenerate and the fourth by division forms the pronuclei. Cytoplasm and pronuclei from one conjugant pass over into the other, leaving the old macronucleus and a minimum of cytoplasm behind in the shrunken pellicle of the smaller conjugant, which then separates from the larger one. In the larger exconjugant two pronuclei fuse, forming the functional synkaryon; the two residual pronuclei degenerate and disappear. The synkaryon divides. One of the daughter nuclei condenses into the new micronucleus, the other grows into the new macronucleus. The old macronucleus liquefies and is absorbed. The larger exconjugant, after losing its cilia, secretes a cyst wall about itself and becomes dormant. The whole process requires at least six days for its consummation.
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  • 57
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: In conjugation fusion occurs along the entire oral surfaces of the proboscides of Dileptus gigas. Two size-reducing divisions occur in rapid succession immediately preceding conjugation. Only one of the many micronuclei takes part in the process of nuclear reorganization. All other chromatic material is massed at this time in the posterior portions of the conjugants. The pronuclei are derived from the single active micronucleus, and interchange occurs immediately preceding the separation of the mating individuals. The fertilization nucleus divides to form two nuclei of diverse size. The smaller one produces thirty-two or sixty-four micronuclei, while the larger one divides to produce a like number of macronuclei, each of which finally breaks up into many chromatic granules which form the numerous densely staining nuclear derivatives which are characteristic of the vegetative stage of Dileptus gigas.In the early stages of this reorganization process specimens are frequently found with from two to eight distinct nuclei often arranged in a series as in a beaded nucleus. This condition probably explains the frequent references in literature regarding such a nuclear condition in Dileptus.Dileptus gigas has, accordingly, in the vegetative stage, a multinucleate condition with reference to the micronucleus and a fragmented or distributed condition with reference to the macronucleus.
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  • 58
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    Notes: By the use of a satisfactory technique, excellently preserved spermatogenetic tissue was had both for Rattus rattus and Rattus norvegicus. The careful examination of twelve spermatogonial cells of the former species and of twenty in the latter species shows that R. rattus has forty diploid chromosomes and R. norvegicus, forty-two. A careful examination of the haploid cells of both species, both in the first and in the second spermatocyte divisions, confirms the diploid determinations.Both species have an unequal pair in the spermatogonial divisions and the finding of a similar unequal pair in the first spermatocyte division constitutes the evidence for an X-Y mechanism in each. A comparison of the morphology of the first spermatocyte tetrads in the two species reveals the presence of a large K-shaped chromosome in R. norvegicus which is not present in R. rattus. Furthermore, a comparison of the X-Y complex in both the spermatogonial and first spermatocyte divisions shows that these are morphologically different in the two species, the Y in particular being markedly dissimilar in size. A short discussion as to the bearing of these findings on the questions of the origins of the two species and their known intersterility is presented. The marked similarity of the tetrads of the black rat to those described for the mouse is noted.
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  • 59
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    Journal of Morphology 44 (1927) 
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  • 60
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    Journal of Morphology 44 (1927), S. 29-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anlage of the abducens musculature appears first at 24-25 somites as a condensation situated dorsal to the mandibular arch.The anlage of the superior oblique grows forward from a mesodermal condensation situated in the maxillomandibular region, termed for convenience the maxillomandibular condensation. This last consists of three parts: (1) the anlage of the superior oblique: (2) the anlage of the abducens musculature, and, (3) an intermediate region.The intermediate portion of the maxillomandibular mass forms a condensation with which the anlage of the abducens musculature fuses. Its fate is, therefore, similar to that of the so-called ‘muscle E’ of elasmobranchs, which has been described as fusing with the lateral rectus. How much muscle is formed from the intermediate condensation in the chick has not been determined.The development of the pyramidalis and quadratus nictitans muscles, derivatives of the abducens complex, is described.The premandibular head cavities are replaced by solid mesodermal condensations, on the surface of which the anlagen of the oculomotor muscles appear. The premandibular mass expands laterally and anteriorly over the bulbus, carrying the oculomotor muscles to their respective positions on the bulbus.Portions of the premandibular and maxillomandibular condensations not involved in eye-muscle formation take part in the formation of choroid and sclera.The growth shiftings of the eye muscles are analyzed. The order of their appearance is commented upon.
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    Journal of Morphology 44 (1927), S. 127-216 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study represents the first critical investigation on the development of the embryonic skull of the porcupine. A complete series of stages makes it possible to trace the developing chondrocranium from its first formation in precartilage to its later transformation into cartilage bone. Concurrent with this growth is the investment of the cartilaginous cranium by membrane bone.The very primitive nature of the chondrocranium offers an excellent opportunity to discuss the existing problems of the embryonic skull from a new angle. Evidence is presented in support of the assumption that the ala temporalis is the homologue of the cynodont epipterygoid. The lamina parietalis develops from a single chondrifying center, thus producing a different arrangement of parietal elements from that found in most mammals. New evidence as to the relationship of the dens epistrophei and basal plate is presented. The position of the internal carotid artery on entering the cranium is different from the condition found in most mammals and throws new light on the interpretation of surrounding structures. The presence of a structure comparable with the crista longitudinalis of Lacerta shows close affinity to the solum nasi of more primitive forms.The great specialization of the face is seen in the early and rapid growth of the membrane bones. The chondrocranium is long persistent and cartilage bone appears late in embryonic life.
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  • 62
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    Journal of Morphology 44 (1927) 
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  • 63
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    Journal of Morphology 44 (1927), S. 417-465 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations indicate that this Balantidium from the guinea-pig is Balantidium coli, the form found in the pig and man. The lengths and breadths of this Balantidium and the ratios of length to breadth are very close to the measurements and ratios given by McDonald for B. coli. When plotted, the body lengths of the guinea-pig parasites appear in two groups, the smaller individuals being the exconjugants. Many of these exconjugants resemble Neiva's B. caviae. The structure of the Balantidium from the guinea-pig is essentially identical with that of B. coli as given by McDonald.Fission and conjugation of this ciliate follow the general course found in a number of other ciliates. During fission the micronucleus divides and the daughter micronuclei migrate to each end of the macronucleus before the latter divides. In conjugation there are two divisions of the micronucleus, one of these nuclei dividing to form the pronuclei. Pronuclear exchange and fusion are followed by a heteropolar division of the synkaryon, resulting in the formation of the new macronuclear and micronuclear anlagen.The parasite was found in the intestinal tissue of the host. No reproductive stages were found in the cysts. New hosts are invaded through contamination of the food and drink with the cysts.
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  • 64
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    Journal of Morphology 43 (1927), S. 347-385 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the thigh musculature in a series of chick embryos is described and figured. In the earliest the muscular tissue is in the form of two distinct masses lying on opposite surfaces of the limb. Later, both divide into proximal and distal portions at the knee. The proximal portions, by a series of divisions, gradually attain the condition found in the adult thigh.The embryological findings tend to support the theory of the derivation of tetrapod limb musculature from the two opposed (dorsal and ventral) muscle masses of the paired fins of bony fish.The reptilian homologies of the ilio-trochanterici cannot be definitely ascertained from embryological evidence.The ischio-femoralis (= ischio-trochantericus), Previously regarded as dorsal, and the coccygeo-femorales, previously classed as incertae sedis, are in reality members of the ventral group.The distinction between ‘intrinsic’ and ‘extrinsic’ muscles inserting on the free limb appears to have no embryological or phylogenetic basis in fact.Double innervation (motor) is a primitive condition in tetrapods.Rotation of the avian pubis is correlated with an improved functioning of the obturator in the rotated position coupled with a lack of interference with the other musculature concerned.
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  • 65
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    Journal of Morphology 43 (1927), S. 547-555 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The diploid number of chromosomes obtained from counts of anaphases of the first somatic mitosis is found to be forty-four. Of these, seven have terminal, thirty-seven non-terminal attachment, giving a distribution of seven rods, thirteen V's, and twenty-four J's. The number is constant in all the fertilized eggs counted, indicating an XX-XY arrangement of the sex chromosomes.
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  • 66
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    Journal of Morphology 168 (1981) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 67
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    Journal of Morphology 168 (1981), S. 121-135 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper describes the regeneration of the caudal axial skeleton after amputation of the tail, including about 20 vertebrae, in the gymnotoid fish Eigenmannia virescens. Seven days after amputation, a regeneration blastema developed and soft tissues degenerated. A cylinder of cartilage developed at the end of the notochord. When this cartilage was about 10 mm long (21 days), perichondral ossification began. The cartilage continued to elongate and ossification increased while osteoclasts began to destroy the cartilage ventrally. Finally, a bony rod formed and at its tip the cartilage persisted as a rod, 2 to 3 mm long. The anal fin also regenerated: Endoskeletal cartilage developed first, following by differentiation of the lepidotrichia, and finally ossification of the endoskeleton.
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  • 68
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    Journal of Morphology 167 (1981), S. 91-102 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The endemic Antarctic teleosts of the suborder Notothenioidei are bottom dwellers. They lack swim bladders, are heavier than seawater, and feed on or near the bottom. The midwaters surrounding the Antarctic continent are productive and underutilized by fishes. There is an evolutionary trend toward pelagism in some notothenioids. We discovered that the largest Antarctic fish, Dissostichus mawsoni, was neutrally buoyant. Attainment of neutral buoyancy was associated with specializations of the skeletal, integumentary, muscular, and digestive systems. The skeleton had a low mineral content and contained considerable cartilage. Scales were also incompletely mineralized. Static lift was obtained from extensive lipid (mostly triglyceride) deposits. A 2-8 mm subcutaneous lipid layer accounted for 4.7% of the body weight. White muscle also contained much lipid-23% on a dry weight basis, or 4.8% of the body weight. Microscopic examination suggested that the liver was active in lipid metabolism, although it was not an organ of buoyancy. Stellate (perisinusoidal) cells with many lipid droplets were a very prominent cytological component of the liver. These specializations made Dissostichus neutrally buoyant and capable of inhabiting the food-rich Antarctic midwaters.
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  • 69
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    Notes: The spongillid freshwater sponges asexually produce an encapsulated dormant stage, the gemmule. With release from dormancy, internal, yolk-laden, binucleate thesocytes differentiate into histoblasts or archeocytes. The histoblasts emerging first from the gemmule form the initial pinacoderm of the hatching sponge. Immunohistochemistry was employed to examine the distribution of cyclic GMP (cGMP) and cyclic AMP (cAMP) following dormancy release and during gemmule germination and hatching in the freshwater sponge, Spongilla lacustris L. Cyclic nucleotide fluorescence patterns were analyzed in relation to the distribution of cytochemically demonstrable macromolecular constituents and intracellular organelles. Twenty-four hours following temperature-activated release from dormancy, cGMP fluorescence levels are elevated in thesocytes at the gemmule periphery prior to histoblast formation. The cAMP fluorescence in the gemmule also occurs first in those thesocytes differentiating into histoblasts. Cytochemical patterns in germinating gemmules are comparable with those described by Ruthmann ('65) and Tessenow ('69). However, cytochemically demonstrable events of cytodifferentiation follow the earlier appearance of cGMP and cAMP in the histoblast precursors by approximately 12 hours. In addition, cGMP appears to be associated with the membranes of cytoplasmic organelles, possibly lysosomes or lipid inclusions, in the region of vitelline platelets and with symbiotic algae. cAMP is located primarily on the membranes of the vitelline platelets and on membranes of vacuoles involved in forming the spicular skeleton These observations suggest that cGMP and cAMP are involved in the mobilization of nutrient reserves and in ion transport during dormancy release and development from gemmules in freshwater sponges.
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  • 70
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    Journal of Morphology 167 (1981), S. 119-134 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cranial nerves of the cutlassfish, Trichiurus lepturus, were described from their external brain origin to their most distal points. The nervus olfactorius, nervus opticus, nervus oculomotorius, nervus trochlearis, nervus abducens, nervus glossopharyngeus, and nervus vagus of Trichiurus are characteristic of teleosts. The cephalic autonomic nervous system also follows the general scheme for teleosts.Atypical patterns are exhibited by portions of the ramus mandibularis facialis, ramus mandibularis trigemini, nervus stato-acusticus, and nervus lineae later-alis. A cutaneous ramus mandibularis externus facialis arises from the ramus mandibularis; this cutaneous nerve has been recorded specifically in only certain siluroid catfish. A connection from the ramus mandibularis trigemini to the cutaneous ramus mandibularis externus facialis is present; an equivalent of this connection has been reported only in the silversides, Menidia, and the siluroid catfish Parasilurus. This nerve pattern probably represents an archaic arrangement. The nervus stato-acusticus of Trichiurus is typical for teleosts, except for a branch extending from the posterior part of the nerve; this branch sends connections to the nervus lineae lateralis and then exits the cranium via the vagus foramen. Connections between the nervus lineae lateralis and the nervus stato-acusticus have previously been reported in only the hatchetfish, Argyropelecus, and the bristle-mouth, Cyclothone. This condition may represent a specialized adaptation of certain mesopelagic teleosts having extreme vertical-migration capabilities.
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    Journal of Morphology 167 (1981) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 72
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    Journal of Morphology 168 (1981), S. 229-237 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Males of the cockroach, Nauphoeta cinerea (Olivier), possess a thickened secretory epithelium limited to the inner surfaces of sternites three to seven and tergites two to eight. The epithelium consists of three cell types: 1. large columnar secretory cells, 2. squamous nonsecretory cells, and 3. duct cells. Type 1 cells constitute the innermost layer and contain large nuclei and vacuoles, which are especially prominent in the epidermis of older males. This cell type may be involved in “seducin” secretion. Type 2 cells lie in the narrow basophilic zone which separates the secretory cells from the cuticle. Here, cellular boundaries are poorly defined. Type 3 cells with condensed nuclei are associated with cuticular ductules leading from the epidermis to the exocuticle. The epidermal height in the secretory zone of the sclerites approaches 40-200 μm depending on the age of the male. The changes in appearance of the secretory cells (increase in height and vacuolation) indicate heightened secretory activity. This is supported by the results obtained when extracts of these regions from different aged males are bioassayed for pheromone (Dimeo et al., '78). A striking difference in the morphology of the cuticle and epidermis of the secretory halves of sternite and tergal integument is noticeable.
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  • 73
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    Journal of Morphology 168 (1981), S. 239-245 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitotic waves during superficial cleavage and early gastrulation were analyzed quantitatively in Calliphora. Three consecutive patterns are present: (1) a monotonic anterioposterior mitotic gradient during early superficial cleavage; (2) a double mitotic gradient from the anterior and posterior poles during superficial cleavage, especially toward the end of the period; and (3) more complicated patterns with intermediate mitotic centers during the last superficial cleavage division and during early gastrulation. Mitotic gradients are absent in many eggs during early superficial cleavage, but they then become ubiquitous. The gradients are longitudinal; no transverse component was detected before gastrulation. Anterior and posterior gradient patterns are not mirror images of each other; mitotic activity always starts earlier anteriorly. The gradients are accompanied by a pronounced increase in interphase length. The mitotic gradients are compared with the morphogenetic gradients predicted in a current model for pattern specification in insect eggs.
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  • 74
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    Journal of Morphology 168 (1981), S. 289-295 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Marked tendinous bands lie along the lateral sides of the fingers in Varanus and Iguana and have asymmetrical roots in the metacarpal region. The radial band of each finger represents the distal extension of an oblique band arising at an ulno-dorsally located line in the proximal part of the metacarpal, whereas the ulnar bands each form a tendinous extension of an interosseus muscle bundle. The function of this metacarpo-digital system must be seen in relation to the deformations of the hand, imposed during locomotion by longitudinal rotation of the forearm. The latter motion results from the foreward and backward sway of the humerus with the elbow bent at 90°.
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  • 75
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    Journal of Morphology 168 (1981), S. 249-267 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two aspects of the avian renal cortical microanatomy previously were unclear. The precise in situ folding patterns and orientations of the nephrons with respect to the other cortical elements had not been demonstrated. It also was not known whether certain nephron segments are supplied exclusively by either the arterial or the portal blood flow. In the present study, a new casting compound was developed to allow selective examination of the cortical components by light microscopy. Cortical nephrons at the surface of the kidney were serially sectioned and reconstructed in order to determine: (a) their relationships to the vasculature and collecting ducts; (b) the location and characteristics of the tubule segments; and (c) the primary and secondary folding patterns of the tubules. The anatomical findings were documented individually and then summarized in a comprehensive diagram of the superficial cortical microanatomy. In addition, an in vivo method was used to determine the extent of portal blood distribution to the nephron segments. It was demonstrated that renal portal blood suffuses all of the segments except for the loops of Henle.
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  • 76
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    Journal of Morphology 168 (1981), S. 331-338 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The theory of Kukalova-Peck ('78) is examined and rejected except for the hypothesis of the partially pleural origin of wings. Data suggest that the arthropods ancestral to insects left the water, and that movable precursors of the wings, possibly exopodites, were immobilized and fused with the tergum to form part of the complex paranota. Later, during insect adaptation for flight, parts of the complex paranota were separated secondarily and became wings.
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  • 77
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    Journal of Morphology 169 (1981), S. 225-242 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study provides a detailed account of the development of the digestive system of larval lobsters (Homarus americanus H. Milne Edwards, 1837) and the morphological changes that occur at metamorphosis. The most dramatic of these changes involves the gastric mill of the cardiac stomach. First-and second-stage lobsters lack the medial and lateral teeth characteristic of the grinding stomach of adult lobsters. Clearly recognizable, heavily cuticularized teeth first appear in the third stage, and accessory lateral teeth do not appear until the fourth stage. In place of the teeth of the gastric mill, first- and second-stage stomachs have a series of pads and ridges which are the apparent rudiments of the teeth. The development of the gastric mill during the larval stages enables lobsters to deal successfully with the more substantial food they encounter in the benthic environment, and corresponds to the drastic change of habitat and diet which occurs at metamorphosis.Confusion about the extent of the midgut and hindgut in larval lobsters has been clarified. The results of this study have shown that the larvae have a long midgut, which lacks a cuticle, and a short hindgut with a cuticular lining, just as in adult lobsters. The junction between midgut and hindgut lies in the sixth abdominal segment in all of the first four stages, as well as in the adult.
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  • 78
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    Journal of Morphology 169 (1981), S. 275-281 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The embryonic development of the viviparous scorpion, Heterometrus fulvipes, has been followed throughout the gestation period and the successive stages of the developing embryos have been examined. The morphological features of the embryos are also described and illustrated according to their approximate age.
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  • 79
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    Journal of Morphology 169 (1981), S. 293-323 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vascular system of the digits of the tokay is more complex than has hitherto been suspected and has a configuration which suggests it is intimately involved in the process of adhesion. Distinction can be made between lamellae (expanded scales beneath the proximal portion of the digit) and scansors (elaborations of lamellae that contain a large amount of subdermal material and therefore do not technically qualify as scales). Such a distinction is made on anatomical grounds and can be appreciated only if anatomical investigation is carried out. There are no externally obvious features by which lamellae and scansors can be distinguished, except position. Scansors are found beneath hyperextensible phalanges, whereas lamellae are located more proximally and are not subjected to digital hyperextension during locomotion. Whether this distinction can be applied to other pad-bearing geckos and to anoline lizards remains to be seen.The large sinus beneath the penultimate phalanx appears to govern the pressure within the system; the reticular blood systems of the scansors appear to manifest the pressure changes with respect to the locomotor substratum. Changes in pressure within the system probably permit the overlapping scansors to comply precisely with each other and with the substratum. The presence of a system based on fluid pressure differentials means that scansors are deformable along multiple axes at any one time, thus permitting a high degree of compliance with their entire surroundings. It is probable that changes in pressure within the system promote release from the substratum as well as compliance with and attachment to it. The mechanism of control of the system awaits further investigation.The pattern of the digital vascular complex has been considered in relation to the mode of operation of the digits during locomotion. Distal drainage of the sinus is ideally suited to the activity of hyperextension of the digits. This combination permits sequential pressurizing and depressurizing of the scansors and allows the bond to be created or broken in a gradual fashion rather than in an all-or-none manner. By avoiding sudden shifts in the pattern of dynamic loading (the bond is not broken instantaneously but sequentially), the risk of transverse instability during locomotion is lessened. The increase of loading on the other feet is thus gradual. The importance of this is discussed more fully elsewhere in a consideration of the structure and function of scansors. That the digits of the tokay are hyperextended during horizontal as well as vertical locomotion (Russell, '75, p. 463) can now be rationalized not only from the point of view of protection of the setae but also because of the manner in which the vascular system of the digits functions and is drained.
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    Journal of Morphology 170 (1981), S. 29-42 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retinal afferents and efferents were examined in Crotalus viridis. Retinofugal fibers were traced by injecting horseradish peroxidase (HRP) or tritiated leucine into the eye, or by removing the eye and staining degenerating axons with silver methods. Terminations were seen contralaterally in the suprachiasmatic nucleus, the dorsal and ventral lateral geniculate nuclei (extensive), the pretectal nuclei, including the nucleus posterodorsalis (a very heavy input), the nucleus lentiformis mesencephali, nucleus geniculatus pretectalis, and nucleus pretectalis, the superficial layers of the optic tectum, including the stratum zonale, the stratum opticum, the stratum griseum et fibrosum centrale and the upper portion of stratum griseum centrale, and the basal optic nucleus. Ipsilateral input reaches the intermediate portion of the dorsal lateral geniculate nucleus, a small portion of the pretectal nucleus and nucleus posterodorsalis, and the basal optic nucleus (very minimally). Retinopedal fibers were traced with the HRP method. The cell bodies lie in the ventral thalamus within the nucleus of the ventral supraoptic decussation. These neurons project primarily to the contralateral retina, but some more rostrally located neurons project to the ipsilateral retina.
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  • 81
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    Journal of Morphology 169 (1981), S. 253-257 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Mesenchyme in the hind limbs of Rana pipiens tadpoles may serve as an important influence on the development of specific neural structures involved in limb innervation. Thus a histological quantification of mesenchyme was undertaken to identify landmark stages with respect to mesenchyme presence and neural events. Mesenchyme remained as a high percentage of the limb tissue until stage V (Taylor-Kollros stages, '46), after which it declined dramatically until its virtual absence after stage XI. The volume of mesenchyme, however, was greatest at stages VIII-IX. Periods of high and low mesenchyme content were correlated in time with potential limb involvement in regulating limb innervation and motor neuron loss from the lateral motor columns. This provides additional evidence for developmental relationships between events of the limb and neural tissues.
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  • 82
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    Journal of Morphology 170 (1981), S. 171-180 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: In this paper we document retial supply of the spinal cord and describe the arterial vascular pattern of the brain in the whale family Monodontidae. Observations are based on gross dissections of four brains, two each of Monodon monoceros and Delphinapterus leucas, and one spinal cord from M. monoceros.Vessels of the spinal cord arise from extradural retia in the neural canal. Arteries originating from the retia penetrate the dura between successive spinal roots (mainly ventral) and not in association with them, unlike radicular arteries of other mammals. Also, these vessels are uniformly distributed and contribute equally to a plexus surrounding the cord. An A. radicularis magna is not present, and neither are dìstinct anterior or posterior spinal arteries.Circulation to the brain is effected by two pairs of arteries originating from intracranial retia. The rostral pair supplies most of the forebrain (prosencephalon), whereas the more caudal pair supplies mainly the midbrain (mesencephalon) and hindbrain (rhombencephalon). The circulatory pattern is characterized by (1) complete independece of anterior cerebral arteries (no anastomoses); (2) extensive cortical supply by the anterior choroidal arteries; (3) absence of subdural communicating vessels between rostral and caudal trunks; (4) union of caudal trunks to form a small basilar artery; and (5) absence of vertebral arteries and hence of a vertebral basilar system. There are some obvious differences between subdural arteries in the Monodontidae and those in other mammals; however, their general patterns of distribution are similar, and we suggest that most of the vessels, at least in the cranium, are homologous.
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    Journal of Morphology 170 (1981), S. 147-169 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Optoelectronic analysis of mandibular movement and electromyography (EMG) of masticatory muscles in Cavia porcellus indicate bilateral, unilateral, and gnawing cycles. During bilateral and unilateral cycles, the mandibular tip moves forward, lateral, and down during the lingual phase of the power stroke to bring the teeth into occlusion. EMG activity is generally asymmetric, with the exception of activity of the temporalis muscle during bilateral cycles. During gnawing cycles, the mandible moves in an anteroposterior direction that is opposite that during bilateral and unilateral chew cycles. Bilateral and unilateral cycles of pellets were significantly longer than carrot. With the exception of the width of bilateral cycles, the magnitude of cycle width, length, and height during the mastication of carrots was greater than that during the mastication of pellets. Significant differences exist between EMG durations during mastication of pellets and carrots. The lateral pterygoid displays continuous activity during gnawing cycles. Significant differences also exist in the durations of EMG activity between the working and balancing side during all three cycle types. High level activity of balancing side temporalis and anterior belly of digastric (ABD) during bilateral cycles occurs during rotation and depression of the mandible during the power stroke. The temporalis apparently provides a „braking“ or compensatory role during closing and power strokes. Differences between Cavia masticatory patterns and those shown by Rattus and Mesocricetus are apparently due to differences in dental morphology, occlusal relationships, and, possibly, the poorly developed temporalis in Cavia. The large number and wide diversity of rodent groups afford students of mammalian mastication an opportunity to investigate and compare different masticatory specializations.
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  • 84
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    Journal of Morphology 170 (1981), S. 239-251 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning electron microscopy was used to characterize the external morphology of the molar surface of the mandibles of the brine shrimp, Artemia salina. Unlike many other branchiopod crustaceans, Artemia has symmetrical mandibles, ie, the molar surfaces of the two mandibles of an individual are similar in size and surface structure. Each molar area has three basic regions: the anterio-ventral region, posterio-dorsal region, and transition zone. On the anterio-ventral region there are complex, parallel furrows and ridges, which are specializations for clasping masses of fine, particulate food. The general surface of this ridged area is flat, except at the ventral and anterior edges, where there is a fringe of long projections that probably serve to retain food in the space between the paired mandibles. The posterio-dorsal region, which has simpler, more sparse cuticular projections, is adapted for reception of food. Stereomicrographs reveal that the general surface of this region is sloped and thus forms a cleft along the posterio-dorsal margin of the two apposed molar surfaces. Anatomical relstionships suggest that the cleft is an adaptation for accommodating maxillular setae that push food forward onto the mandibles. The transition zone has cuticular specializations that are morphologically intermediate between those of the anterio-ventral and posterio-dorsal regions. Three types of pores, possibly openings of glands or sensilla, were observed in the cuticle of the molar surface.
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    Notes: An aggregation of sessile spherulocytes in the cephalon of female Gammarus setosus surrounds the ramifications of the dorsal aorta and the peripheral ganglion of the frontal organ nerve. It is not a hemopoietic organ. The spherulocytes are of three distinct varieties that may represent phases of a secretory cycle possibly synchronized with molting or reproduction. In addition, four other hemocyte types were identified in the cephalic blood sinuses: prohemocyte, plasmatocyte, granulocyte, and adipohemocyte. The cellular and nuclear dimensions of these hemocytes were analyzed. They were shown to be uniform in cell size with average cell area of 69.27 μm2, and average maximum cell diameter of 11.75 μm. The mean nuclear area and mean maximum nuclear diameter of the prohemocyte are significantly larger than those of the other cell types. The structure of the hemocyte types is described and compared to those of other crustaceans and insects.
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    Journal of Morphology 170 (1981), S. 283-299 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructural features of spermatogenesis were investigated in the nudibranch mollusc Spurilla neapolitana. Sperm develop in the proximal half of numerous sac-like acini which are radially arranged within about ten ovotestis lobes. Accessory cells line the inner wall of the testicular portion of each acinus and are connected to developing sperm by numerous desmosomes. Stages of spermatid development have been divided into precup, cup, postcup, and elogate stages depending on the general shape of the nucleus. Nuclear differentiation includes the formation of anterior and posterior nuclear plaques, condensation of chromatin fibrils into nuclear lamellae, the insertion of the developing flagellar axoneme into a shallow, nuclear implantation fossa, and eventual formation of an elongated sperm head with a terminal twist. Spermiogenesis also includes the differentiation of an anterior, perinuclear structure having the characteristics of an acrosome, the appearance of peculiar arrays of ER cisternae, and the fusion of mitochondria into a large mitochondrial derivative which eventually encircles the axoneme, forming a crystalline-like periaxonemal sheath.
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    Journal of Morphology 170 (1981), S. 357-372 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Feet of two-toed sloths (Choloepus) are long, narrow, hook-like appendages with only three functional digits, numbers II, III, and IV; Rays I and V are represented by metatarsals. Proximal phalanges of complete digits are little more than proximal and distal articulating surfaces. All interphalangeal joints are restricted, by interlocking surfaces, to flexion and extension. Ankle and transverse tarsal joints, however, allow extreme flexion and inversion of foot. Powerful digital flexion is augmented by several muscles from extensor compartment of leg. Intrinsic foot musculature is reduced to flexors and extensors but these, with the exception of lumbricals, are large and well developed. Choloepus uses its feet much like hooks with distal phalanges and covering claws forming the “hook” element. These hook-like appendages are seemingly best suited for supports less than 50 mm in diameter suggesting that two-toed sloths may prefer supports of this size in their natural habitat.
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    Journal of Morphology 170 (1981), S. 383-399 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The perirhopalial tissue and swimming muscle of Cyanea were examined with light microscopical and electron microscopical techniques. The perirhopalial tissue is a thin, triangular septum found on the subumbrellar surface of the animal. It separates part of the gastric canal system from the surrounding seawater, and is bound on two sides by radial muscle bands and on the third, the shorter side, by a rhopalium and the margin of the bell.The ectoderm of the perirhopalial tissue is composed of large, somewhat cuboidal, vacuolated, myoepithelial cells. The muscle tails of these cells form a single layer of radial, smooth muscle. Neurons of the “giant fiber nerve net” (GFNN), which form an extensive net over the perirhopalial tissue, lie at the base of the vacuolated portion of the myoepithelial cells. These neurons are visible in living tissue. The morphology of individual GFNN neurons was examined following intracellular injection of the fluorescent dye Lucifer Yellow. The neurons are usually bipolar and free of branches. At the electron microscope level, one usually finds that the GFNN neurons contain large vacuoles. The other characteristic feature of these cells is that they form symmetrical, or nonpolarized, synapses; that is, synaptic vesicles are found on both sides of the synapse.The swimming muscle is striated and composed of myoepithelial cells. Each myoepithelial cell has several muscle tails, and those of adjacent cells are linked to gether by desmosomes. The endoderm of the perirhopalial tissue also was examined.This investigation of the organization and ultrastructure of the perirhopalial tissue and surrounding muscle was undertaken to provide essential background information for an ongoing physiological study of the GFNN neurons and their synapses.
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    Journal of Morphology 170 (1981), S. 373-382 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to determine the temperature sensitive stages for sexual differentiation of the gonads in Emys orbicularis, eggs of this turtle were shifted at different stages of embryonic development from the male-producing temperature of 25°C to the female-producing temperature of 30°C and reciprocally. Based on the series of developmental stages described by Yntema (′68) for Chelydra serpentina, temperature begins to influence sexual differentiation of Emys orbicularis at stage 16, a stage in which the gonads are still histologically undifferentiated. Its action lasts over the first steps of histological differentiation of the gonads. The minimal exposure at 25°C required for male differentiation of all individuals extends from stage 16 to somewhat before stage 21. For 100% female differentiation, incubation at 30°C must be longer, from stage 16 to somewhat before stage 22. Shorter exposures at 25°C or 30°C during these periods result in different percentages of males, females, and intersexes. Our results show that there is a critical stage (stage 16) which is the same for both male and female differentiation of the gonads. The thermosensensitive periods are rather long, corresponding to 11-12 days at 25°C and 30°C.
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    Journal of Morphology 170 (1981), S. 271-272 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Morphology 170 (1981), S. 301-319 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of the heart of Geukensia demissa, a common object of physiological and biochemical investigation, is described by scanning, transmission and freeze-fracture electron microscopy. A single-cell epithelial layer covers the ventricle, but an endothelium is lacking. Myofibers are small (6-7 μm diam.), mononucleate, and tapered. Glycogen is concentrated peripherally. Mitochondria are particularly concentrated under the sarcolemma, near the ends of the nucleus, and in rows between bundles of myofilaments. The myofilaments (6-8nm thin, 30-35 nm thick filament diam.) are loosely arranged into sarcomeres (2-4 μm) by Z bodies. Many of these Z bodies interconnect, and some anchor to the sarcolemma forming attachment plaques. Cells are joined by intercalated discs consisting of fascia adherentes, spot desmosomes, and gap junctions. The gap junctions include intramembrane particles. T tubules are absent. The sarcolemma is coupled to the junctional sarcoplasmic reticulum (JSR) over 357ndash;40% of the cell surface. Tubules extend from the JSR deep into and throughout the cell as an irregularly dispersed network. The SR occupies 1% of the cell volume. A few, small (0.1-1.0 μm) unmyelinated nerves are present, but no neuromuscular junctions were seen. The auricles have fewer and smaller myocytes than the ventricle. The auricles also contain podocytes with pedicels having 20-35 nm slits and containing sieve-like projections. The morphology of the Geukensia heart is similar to that of other bivalves.
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    Journal of Morphology 170 (1981), S. 401-401 
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    Journal of Morphology 40 (1925), S. 169-189 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A review of the literature of the gastric glands of reptiles shows marked differences of opinion concerning the nature and character of the cells composing the gastric glands.The present investigation of the gastric glands of the alligator has been carried out by histochemical and physiological experiments, rather than by the usual morphological methods, but the results can be stated both in terms of structure and function.1The surface epithelial cells and those lining the gland pits in the fundic, cardiac, and pyloric regions of the stomach of the alligator are not strictly comparable functionally to the mucous cells of mammals.2The cells composing the necks and bodies of the glands in the fundus, according to histochemical reactions, are parietal cells.3Certain cells lying beneath the columnar epithelial cells lining the lumen of the stomach and the foveolae react to one method of fixation and staining as do the chief cells of mammalian material.4The results of the experiment with the vital dye, neutral red, show that the cells of the gastric pits, the necks and bodies of the glands in the fundus of the alligator's stomach, react identically as those of the mammalian stomach.5The gastric juice of the alligator is acid to litmus-paper and contains a free mineral acid.
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  • 94
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 299-340 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The course of digestion of an essentially protein food (beef liver) was followed by histological and histochemical methods in Planaria dorotocephala. After an average fasting period of two weeks, the planarians were fed and examined at close time intervals, ranging from one minute to eighty-seven days after feeding. Liver particles are engulfed by the phagocytic cells of the intestine into food vacuoles, where a series of digestive changes occur. The liver particles coalesce into a granular spherule which gradually condenses into a homogeneous and chromatophilic spherule. As the spherule transforms from a granular to a homogeneous condition, it exhibits a gradually increasing affinity for stains, an intensified protein reaction, and a gradual diminution in size. These spherules are protein, since they give positive xanthoproteic and Millon reactions.The homogeneous protein spherules gradually disappear, beginning at about twelve hours after feeding and continuing until the fifth day. During this period fat-droplets form, gradually increasing at the expense of the protein spherules. The protein spherules apparently dissolve into the cytoplasm, furnishing intermediate chemical compounds (tests indicate that a carbohydrate stage does not intervene) from which fat is synthesized. It thus appears that the fat is formed from the protein spherules. The fat thus formed is stored in the phagocytic cells, and remains unchanged in quantity for a fasting period lasting six weeks, after which it gradually diminishes. During the engulfment of the food, the fat decreases markedly, apparently furnishing energy for phagocytic activities. A few of the protein spherules may persist as «protein reserve».
    Additional Material: 7 Ill.
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  • 95
    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
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 40 (1925), S. 111-167 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microscopic examination of both living and stained forms indicates that the so-called ‘multivacuolate’ and ‘amicronucleate races of Paramecium caudatum’ belong to the species Paramecium multimicronucleata. The published accounts of the morphology and cultural characteristics of the various forms are compared and provide additional evidence. A more complete description is given, including distinctive characters previously omitted.The conjugation process of P. multimicronucleata in general resembles that of P. caudatum, most of the differences being due to the presence of four micronuclei instead of one. These each divide twice with characteristic figures, twelve of the sixteen daughter nuclei then degenerating. One of the remaining four splits to form a single pair of functional pronuclei in each cell. The two migratory pronuclei interchange as in P. caudatum. The synkaryon divides three times, and probably seven of these nuclei degenerate. The remaining one apparently undergoes two divisions. In most cases by six to eight hours after the conjugants separate two micronuclei of the four thus produced form enlarged macronuclear anlagen, the other two remaining as micronuclei. Each anlage divides within the next two or four hours, producing four macronuclear and four micronuclear analagen. Two fissions, each preceded by a division of the micronuclei, restore vegetative conditions.The process described above is compared with conjugation in P. bursaria, P. caudatum, and P. putrinum.
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  • 97
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Systems of fiber-like structures traverse ciliated cells and epithelia in a way to suggest conduction paths for stimuli for coordinating and regulating ciliary movement, and results of microdissection support such an interpretation.Some fibers of the systems in epithelia of the gill terminate on the nuclear membrane, some between nuclei in the basal cytoplasm.The observed double refringency of the fibrillar apparatus places it in the category of irritable and contractile substance.Bipolar cells and nerve-like fibers lie immediately below and parallel with ciliated epithelia of the gill, but direct connections of these fibers with the intracellular system, although suspected, was not demonstrated.Ciliated epithelia of the gill are syncytial in character in the direction of the beat of cilia.Interciliary structures occur in the cuticular portion of ciliated epithelia which are interpreted to function in taking up strains in the gelled cytoplasm caused by the beat of cilia.Cilia occur in pairs in epithelia of the gill, and members of pairs are fused at their distal ends.Each cilium, as seen in dark-field illumination, pierces its basal body, and the fiber that is a continuation of the cilium divides immediately below the basal body into two; one diverging to the right, one to the left.Each cilium is composed of many delicate fibrillae.
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 299-345 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The chondriosomes are first recognizable as two clusters in contact with the nuclear wall. Beneath each cluster lies a chromosome. This relationship is constant and indicates that these two chromosomes play a part in the growth and development of the chondriosomes. The two masses fuse and the single mass grows considerably during the early growth period. Later it breaks up into a number of threads which become rings in the late growth period. The rings fuse into the large nebenkern which plays the usual rôle in the formation of the tail.The Golgi material is first seen outside of the chondriosomal cap. Early in the growth period, it breaks up into Golgi bodies which remain distributed in the cytoplasm during the growth period and spermatocyte divisions. About the midgrowth period a large number of spheres suddenly arise. Since they later fuse to form the idiosome, they are called the proidiosomal spheres. These spheres, which may originate in the Golgi bodies, remain scattered in the cytoplasm during the growth period and spermatocyte divisions. In the spermatid the Golgi bodies collect about the idiosome to form the acroblast. The Golgi remnants pass into the cytoplasm of the tail, while the acrosome elongates into a tail-like structure at the anterior end.The centriole was followed with unbroken continuity from the midgrowth period into the middle-piece of the sperm.
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  • 100
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper contains a description of the appearance and behavior of the chromatin and chief cytoplasmic inclusions in the male germ cells of three species of Belostomatidae.There are eight spermatogonial chromosomes in Lethocerus americanus, twenty-four in Belostoma flumineum, twenty-eight in Benacus griseus. An XY-pair of sex chromosomes occurs in each species. These are identifiable at every step in maturation in Lethocerus, but not in the others. A clear case of heteropycnosis occurs in Benacus. Parasynapsis is believed to be the mode of pairing of chromosomes in all three species. The genesis of three large atelomitic ring tetrads is described in Lethocerus.Chondriosomes are traced from spermatogonia to spermatids without a break in continuity. Spermatogonial chondriosomes are always granular. During the growth period filaments are formed, probably by fusion of granules, and these are sorted out in approximately equal numbers to spermatids. Benacus is especially favorable for studies on chondriosomes. Likewise, Golgi bodies have been traced throughout the process of maturation. They are minute granules in spermatogonia. During the growth period each becomes a flattened plate-like body clearly differentiated into two materials. Dictyosomes are formed by fragmentation in the first prophase, and these are distributed to spermatids where they fuse to form an acroblast in each. Some minor cytoplasmic inclusions are briefly described.
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