bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of anchoring villi of the human placenta
Authors: Enders Allen C. 
Published: February 2005

AbstractAnchoring villi from the first trimester, early second trimester, and term were examined with the electron microscope. It was found that the small anchoring villi of the third and fourth month were particularly informative, since at this stage the cytotrophoblast is still proliferating, yet these cells form a compact discoidal region at the surface of the basal plate. Transitions from relatively undifferentiated cytotrophoblast cells adjacent to the stroma of the villus to large isolated cells surrounded by fibrinoid could readily be followed. These highly differentiated cytotrophoblast cells were found to have extensive regions of fine filaments, in addition to their pronounced endoplasmic reticulum, and were designated fibrous cytotrophoblast cells. The nature of the frequently incomplete epithelium covering anchoring villi at term was described, and some of the functions of the cytotrophoblast are discussed in relation to the observations of their fine structure.
The relationship between the dimensions of the fibres and the number of nuclei during restricted growth, degrowth and compensatory growth of skeletal muscle
Authors: Moss F. P. 
Published: February 2005

AbstractDuring unrestricted growth of the pectoral muscle of chickens, the mean cross‐sectional area of the fibres increased in proporiton to the total number of nuclei and in proportion to the two thirds power of the weight of the muscle. Continuous restricted feeding from 0 day, which limited the weight of the muscle at 16 days to 44% or 69% of that of chickens fed ad libitum, did not affect these relationships.A sudden restriction of feed from eight days of age retarded growth of the muscle to approximately 70% of the weight of the controls at 16 days. It did not affect the relationship between the number of nuclei and the fibre cross‐sectional area, both of which were also limited to about 70% of those of the controls; but it did disrupt the relationship of these two variates to the weight of the muscle. Subsequent ad libitum feeding caused compensatory growth and restored the relationship.Starvation or severe undernutrition for a few days, which reduced weight of the muscle and the fibre cross‐sectional area by approximately 25%, caused no loss of nuclei, thereby disrupting both relationships. Subsequent ad libitum feeding initially caused an increase of muscle weight and fibre cross‐sectional area but no increase in the number of nuclei. This restored the relationships, which were then maintained during subsequent compensatory growth.
Ultrastructure of the lung of the goose and its lining of surface material
Authors: Lambson Roger O. , Cohn Jerome E. 
Published: February 2005

AbstractAs the primary bronchus passes through the goose lung it gives rise to two sets of secondary bronchi. One set is located on the dorsal surface of the lung and the other on the ventral surface. These two sets of bronchi are connected by numerous parabronchi which run parallel to one another through the lung. Each parabronchus is the center of and supplies air to a cylindrical lung lobule. Numerous outpocketings of the parabronchial wall, which are called atria, connect with the finest air spaces of the lung parenchyma.The epithelium lining the parabronchi is continuous with flattened epithelial cells which line the atria and the finest air spaces. The air‐blood barrier is composed of endothelium, a basal lamina, an attenuated pulmonary epithelium, and an 80–120 Å thick osmiophilic layer which covers the attenuated epithelium. Multiple layers of a unit‐membrane‐like material similar to that lining each fine air space is found covering and invaginating the epithelial cells lining the atria and parabronchi. Within many of these atrial and parabronchial cells, laminated osmiophilic material is found within cisternae of rough‐surfaced endoplasmic reticulum, and inclusion bodies which may contain both laminations and a granular matrix similar to that within adjacent Golgi vesicles. It is suggested that the endoplasmic reticulum may be involved in the synthesis of the surface material found lining the goose lung.
Renal morphology of the english sole (parophrys vetulus)
Authors: Bulger Ruth Ellen , Trump Benjamin F. 
Published: February 2005

AbstractThe nephron of the English sole, Parophrys vetulus, is composed of the following regions: a renal corpuscle with few capillary loops and an extensive mesangial area with mesangial cell processes insinuated between endothelium and podocyte basement membrane; a ciliated neck segment with mucous‐containing cells; the first major brush border segment with a broad vacuolated apical zone most closely resembling the mammalian proximal convoluted tubule; a second major brush border segment with the tallest most eosinophilic cells; a gradual transition to a third major brush border segment with lower, more basophilic cells; no distal convolution and a collecting tubule which empties into a collecting duct system. Granulated cells in the arteriolar media appeared to be modified smooth muscle cells.
The ultrastructure of the crevicular epithelium of cat gingiva
Authors: Gavin J. B. 
Published: February 2005

AbstractThe ultrastructure of the crevicular epithelium of clinically healthy cat gingiva was similar to that of other non‐keratinizing oral epithelia. However, it differed in that the intercellular spaces were wide and extended as a continuous network from the basal lamina to the epithelial surface. Basal cells contained numerous mitochondria, Golgi apparatus, free ribosomes and a fine feltwork of evenly distributed tonofilaments. Hemidesmosomes were present in relation to the basal lamina. Cells in the intermediate layers showed a decrease in the number of organelles and an increase in concentration of tonofilaments, Superficial cells were further flattened and the remaining organelles commonly showed degenerative changes. Epithelial cells showed prominent microvilli extending into the intercellular spaces. Some of these formed desmosomes with similar processes of adjacent cells. Occasional randomly distributed tight junctions were also observed. Inactive basal melanocytes, more superficial Langerhans cells and leucocytes were seen between epithelial cells. The great majority of leucocytes were neutrophils and many of these ruptured as they approached the epithelial surface scattering their specific granules into the intercellular spaces. These findings are discussed in relation to the peculiar permeability of the gingival crevicular region of the oral mucosa to tissue fluid and leucocytes.
Cortisone‐induced hypertension and cardiovascular lesions in mice
Authors: Clarke Thomas D. , Ashburn Allen D. , Williams W. Lane 
Published: February 2005

AbstractDaily subcutaneous injections of cortisone acetate (0.5, 1.5 or 2.5 mg) were given to three groups of mice for seven consecutive days. Daily systolic blood pressures of the anesthetized mice were obtained by adapting the method of Friedman and Freed ('49). The maximal arterial pressure increase for the 0.5, 1.5 and 2.5 mg groups was 22%, 31% and 41% respectively. This supports the conclusion that cortisone produces hypertension in mice when administered in large doses. Mural hyalinization, vacuolization and cellular proliferation of coronary arteries were greatest in the 0.5 mg group. The highest incidence of myocardial necrosis, 56%, was in the group receiving 2.5 mg of cortisone daily. The frequency and severity of myocardial and renal cortical necrosis were directly related to the size of the cortisone dose. Adrenal medullary vacuolization and lipid infiltration of the liver were common in all experimental groups.
Light and electron microscopic observations on the spleen and the splenic leukocytes of the newt triturus cristatus
Authors: Tooze J. , Davies H. G. 
Published: February 2005

AbstractThe newt spleen has an outer region, the red pulp, that consists of reticular fibres, reticular cells, and fixed macrophages forming a framework within which erythropoiesis occurs, and an inner region, the white pulp, consisting of a reticular framework containing predominantly lymphocytes. The fine structure of the following leucocytes, namely lymphoid cells, reticular cells, macrophage, haemocytoblasts, plasma cells and neutrophilic, basophilic and eosinophilic granulocytes is, in general, similar to that of the corresponding mammalian blood cells. However, in contrast, all the nuclei contain large numbers of interchromatin granules and a differentiated region termed the nuclear light‐staining zone because of its electron‐scattering properties. Furthermore the specific granules of the eosinophilic granulocytes are structureless whereas those of the basophilic granulocyte have crystalline regions. The structure and distribution of the granular, fibrillar, tubular and vesicular components of the cytoplasm of each cell type is described.
Lymphopoiesis and lymph node histogenesis in the embryonic and neonatal rabbit
Authors: Hostetler Jeptha R. , Ackerman G. Adolph 
Published: February 2005

AbstractThe thymus represents the first lymphocytic organ to exhibit lymphopoietic activity in the fetal rabbit with lymphoblastic transformation beginning by 17 days of gestation, and lymphocytes appearing by 18 days, one to two days before vascularization. Lymphocytes are first evident in lymph nodes at 18 days of fetal development, in the spleen on the twenty‐third day, and in the appendix just prior to birth.Medium‐sized lymphocytes and rare blast‐like cells represent the first lymphocytic cells found in the lymph node anlage. Both of these cell forms appear simultaneously and are distributed randomly. Lymphocytes remain relatively sparse increasing gradually in number until several days prior to birth when their numbers increase rapidly. Coincident with the augmentation in lymphocyte population, lymphocytes tend to cluster near the vascular channels, and are present within the lumina and walls of the smaller veins in the node. Morphological gradations between mesenchymal cells and medium‐sized lymphocytes provide suggestive evidence that the initial population of lymphocytes within the node arise by the direct transformation of the stromal cells into medium‐sized lymphocytes. Less frequently, deeply basophilic blast‐like cells may provide an intermediate stage in lymphocyte differentiation. These cells differ from typical lymphoblasts because of their smaller size and irregular cellular contour.It is postulated that the initial population of lymphocytes formed in the lymph node anlage is derived from the transformation of mesenchymal cells and subsequent homoplastic lymphocyte proliferation and that during later fetal life this population of lymphocytes is complemented by the colonization and proliferation of blood‐borne lymphocytes.
Differentiation of interstitial cells and sertoli cells in fetal guinea pig testes
Authors: Black Virginia H. , Christensen A. Kent 
Published: February 2005

AbstractSmooth endoplasmic reticulum appears in interstitial cells and Sertoli cells of 22–24d testes of fetal guinea pigs before the beginning of morphological differentiation of the male reproductive tract at 29d (Price et al., '67), and before the appearance of demonstrable 3β‐hydroxysteroid dehydrogenase, an enzyme important in steroid biosynthesis, in the interstitial cells at 29d (Ortiz et al., '66). This enzyme has not yet been demonstrated in the Sertoli cells.The smooth reticulum of the interstitial cells increases in amount, filling the cells with tubules by 27d, and later forming some fenestrated cisternae which are occasionally seen in whorls. In Sertoli cells, the tubular reticulum shows signs of degeneration at 26d. After this time the cisternal endoplasmic reticulum in these cells increases in amount and by 45d is predominantly smooth‐surfaced. Yet it is never as prominent as the smooth reticulum of the interstitial cells.Scattered clusters of ribosomes or polyribosomes are seen on the surface of the tubular reticulum of these differentiating cells. These polyribosomes become more widely spaced as the smooth‐surfaced areas increase and may be associated with the production of smooth membranes.Smooth endoplasmic reticulum is known to play a role in the production of steroid hormones, and therefore the extensive development of smooth reticulum in fetal interstitial cells is consistent with experimental evidence that implicates these cells as the chief source of steroid hormones governing male reproductive tract differentiation.
Studies on the thymus of the mammal. XVI. Lipopigment cells in the cortex of the thymus of the mouse
Authors: Smith Christianna 
Published: February 2005

AbstractIn the thymic cortex of mice, certain distinctive lipid‐rich cells, termed foamy cells, were described by Loewenthal and Smith ('52). The abundant cytoplasmic, sudanophilic inclusions of these cells were autofluorescent and PAS positive; these characteristics and others indicated the presence of chromolipoid. Cytochemical reinvestigation of these cells demonstrated acid phosphatase and esterase activities in the cytoplasm. Ultrastructural study of these cells revealed a polymorphic population of residual bodies, most likely of lysosomal origin. Further evidence suggests that a pigment is present which corresponds to an early stage in the development of lipofuscin as stated by Pearse ('60). The characteristics supporting this conclusion are: (1) natural yellow color, (2) yellow fluorescence, (3) weak basophilia, (4) moderate reducing capacity, (5) positive plasmal and PAS reactions, (6) coloring with oil soluble dyes, and (7) variably acid fast. Because of these cytochemical and ultrastructural properties, it is here proposed that these cells should now be called lipopigment cells. Differences in nuclear pattern indicate that they are both epithelial and mesenchymal in origin. Large lipopigment cells gradually develop from smaller cells and accumulate the distinctive cytoplasmic inclusions. Some of these cells are phagocytic. Evidence suggests that the lipopigment cells are long‐lived. The origin of this pigment and its significance in thymic function are unknown.
Accelerated maturation of chick embryo skin treated with a prostaglandin (PGB1): An electron microscopic study
Authors: Kischer C. Ward 
Published: February 2005

AbstractOne of the fatty acid derivatives called prostaglandins, PGB1, when applied to organ cultures of developing chick skin with feather organ loci, completely blocks feather organ development, but stimulates proliferation and keratinization of the epidermis. Control and PGB1 treated explants were harvested after one, two, and three days in culture and processed for study by electron microscopy.Fine structural observation of control and treated skins indicate the following. (1) Tonofilaments appear much sooner in treated explants than in controls, and are distributed at all levels of the epidermis. (2) The cristae of mitochondria in epidermal cells of treated skins are long, closely apposed, and oriented parallel to the longest axis of the organelle as contrasted with a transverse orientation for them in control epidermis. (3) There is increased deposition of collagen in the mesenchyme of treated skins as contrasted to that observed in controls. (4) Unusual structures (inclusion bodies) occur throughout the stratified and superficial epidermis of treated skins and are composed of fine filaments and granules measuring about 30 Å in diameter. They are often associated with tonofilaments. (5) Small but numerous vacuoles appear in the epidermal cells of treated skins and seem to develop from cisternae of the Golgi apparatus or endoplasmic reticulum.The change in orientation of cristae of the mitochondria, vacuolation of the epidermis, and appearance of the inclusion bodies first occurs after two days of treatment with PGB1 in culture. These observations coincide with previous data demonstrating that restitution of feather organ development can be accomplished after one day of treatment with PGB1, but not after two days of treatment.The observations are consistent with an accelerated maturation process, but may be correlated with a specific and irreversible change in a metabolic event necessary for feather development.
The fine structure of the heart valves in the chicken. I. Mitral valve
Authors: Mitomo Yoshio , Nakao Komei , Angrist Alfred 
Published: February 2005

AbstractThe fine structure of the mitral valve in the chicken heart is described. The chicken has no distinct muscular component within the mitral valve; on the other hand, the tricuspid valve is a muscular fold.The mitral valve is a thin, membranous, fibrous structure and is composed of three layers: (a) an auricular and ventricular endothelial layer, (b) a zona spongiosa, and (c) a zona fibrosa. The endothelium of the heart valve resembles closely that of vascular channels, but the shape and size of the valvular endothelial cells vary considerably from those of other vascular channels. From the valvular endothelial cells thin villus‐like projections extend into the cardiac lumen. Their cellular junctions frequently have a complicated pattern in the form of interdigitating folds, although some show a long linerar zone of simple overlapping between adjoining cells. A fine filamentous plexus is a feature of the cytoplasm but is less evident than in other vascular channels. The basement membrane varies with its location in the valve; it is distinct on the atrial side but is often scanty and obscure on the ventricular surface. Some elastic tissue is found in the subendothelial tissue.The zona spongiosa and zona fibrosa are quite similar to those of other species, but the amorphous ground substance in the zona spongiosa is more abundant. Both layes contain elastic fibers and collagen in both fibrils and bundles. Their amount, composition and configuration vary in different locations within the valve.Avian valvular endothelium is compared with that of lining vascular channels and valves of other species. There are structural differences, some of which may reflect physical conditions and function, such as mobility, extensibility and state of contraction.
Ultrastructural studies on fetal and early postnatal mouse ovaries. II. Cytodifferentiation
Authors: Od́or D. Louise , Blandau Richard J. 
Published: February 2005

AbstractThe ultrastructural details of mouse oögonia, oöcytes and follicular cells from fetal day 12 through postnatal day 3 are presented.In fetal oögonia and oöcytes cytodifferentiation proceeds slowly. The most notable change involves an increase in the number of mitochondria and in the size of the Golgi complex. Oögonial itoses, nuclear synaptinemal complexes, true intercellular bridges and multinucleated cells were observed.After the formation of unilaminar follicles with growing oöcytes, cytoplasmic alterations are striking. The Golgi apparatus, previously predominately of vesicular elements, now becomes lamellar in form and occasionally develops complex anastomosing tubules. There may be important functional significance in the relationship established between the Golgi elements and long endoplasmic reticulum cisternae. The membranes of the endoplasmic reticulum cisternae facing the Golgi complex lack ribosomes and exhibit bud‐like evaginations in varying stages of abstriction. Ribosomes are attached to the opposite membrane of the cisternae. Profiles of endoplasmic reticulum are intimately associated with the numerous large mitochondria. Numerous multivesicular and “dense” bodies are present in some oöcytes. Zona pellucida formation is initiated in some of the larger unilaminar follicles.Cytodiferentiation of follicular cells follows a course different from that of the germinal cells in that their cytoplasmic organelles are well differentiated very early in the fetal period. Similarly they send forth the most delicate cytoplasmic extensions which separate adjacent germinal cells. Postnatally, in unilaminar follicles these same cells constitute a flattened epithelial layer containing only a few cytoplasmic organelles. In contrast when these cells become cuboidal and columnar the numerous organelles, as seen in fetal follicle cells, reappear once again. In addition, when the zona pellucida is formed cell processes from these follicle cells extend into it.
Wallerian degeneration in the optic nerve of a reptile: An electron microscopic study
Authors: Kruger Lawrence , Maxwell David S. 
Published: February 2005

AbstractNumerous optic nerve fibers persist for a period of up to 20 months following enucleation in reptiles, although it is unlikely that a significant number of efferent fibers are present. After varying survival periods, almost all nerve fibers display distinct morphological changes probably associated with degeneration, but most features previously associated with early stages of degeneration can be seen in long‐survival material except for the early and rapid loss of all non‐myelinated fibers and a honeycomb tubular degeneration associated with the inner and outer myelin layers. Distinct sequential stages of axon and myelin degeneration could not be ascertained despite the slow rate of degeneration in poikilotherms. The varieties of abnormal axon morphology are documented and considered in terms of current light microscopic staining methods.
The villous period of placentogenesis in the baboon (Papio sp.)
Authors: Houston Marshall L. 
Published: February 2005

AbstractBaboon placentae were studied which ranged in age from 13 to 40 days. Implantation in the baboon is superficial and a single, discoid, villous hemochorial placenta is formed. No chorionic villi develop peripheral to the placenta and there is no decidua capsularis. Trophoblastic tissue within the placenta is of two types, cyto‐ and syncytiotrophoblast. The chorionic villi are short and straight at 13 days but have begun to branch by 16 days. The villi consist of a mesenchymal core surrounded by a single layer of cytotrophoblast which is in turn surrounded by a layer of syncytiotrophoblast. Cytotrophoblastic cells from the distal tips of the villi spread over the maternal surface of the placenta and form a complete cytotrophoblastic shell against the uterine stroma. Maternal blood enters and leaves the intervillous space through clefts in the cytotrophoblastic shell which connect with arteries and expanded venules within the endometrium. A limited decidualization of the uterine stroma takes place.