bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prismatic and other unusual arrays of mitochondrial cristae in astrocytes of cats and hamsters
Authors: Morales Ricardo , Duncan Donald 
Published: February 2005

AbstractFurther work with mitochondria containing prismatic cristae has revealed that this type occurs as a constant feature and in some abundance in the dorsolateral region of the spinal cord of the cat at cervical, thoracic and lumbar levels. All such mitochondria occur in astrocytes. The most common forms are long rods with an abundance of matrix and very few cristae. The matrix in the majority of such mitochondria is of moderate density and without discernible organization. In others the matrix consists of closely packed rodlets with or without occasional prismatic cristae. A frequent pattern is a core of longitudinal rodlets surrounded by a rim of circumferential ones. In the circumferential zone a single row of triangular cristae is present. The unusual mitochondria vary greatly in size, from 0.2–5.0μ Mitochondria containing ordered arrays of cristae that are triangular in cross section are for the most part much smaller than those with very few cristae and smaller than similar mitochondria described in the Syrian hamster. It is concluded that close packing in the matrix (obviously hexagonal in many instances) is the cause of the prismatic shape of the cristae.
Ultrastructural comparisons of paired cisternae in leukemic and mesenchymal cells during mitosis
Authors: Kelley Robert O. 
Published: February 2005

AbstractPaired membranous lamellae were observed in tumor cells from chloroleukemic rats and human embryonic mesenchyme during mitosis. These structures are morphologically identical. Their role during karyokinesis and their relationship to the nuclear envelope is discussed. In addition, it is suggested that at least two mechanisms for breakdown and restoration of nuclear envelope exist during mitosis: (1) vesiculation and (2) lamellation (the formation of membranous lamellae).
Fine structure of a fifth type of epithelial cell in the thyroid gland of the C3H mouse
Authors: Nève Pierre , Wollman Seymour H. 
Published: February 2005

AbstractA new cell with relatively little cytoplasm has been identified in the second kind of follicle in the C3H mouse thyroid gland. It has as ultrastructural characteristics the presence of clusters of fiber in the cytoplasm, vesicles near the basal plasma membrane, and half desmosomes in the basal plasma membrane. It resembles the U cell found in the ultimobranchial follicle of the Fischer rat thyroid, but has a somewhat larger amount of granular reticulum. It is found in the follicle wall between other epithelial cells and the basement membrane, but occasionally is in contact with the lumen. It also occurs as a double layer in the follicle wall. Cell debris in the lumen of the follicle contains fibrils and may be the result of desquamation of this fibril‐containing cell.
Deep splenic lymphatics in the marmot: An electron microscopic study
Authors: Janout Váçlav , Weiss Leon 
Published: February 2005

AbstractDeep splenic lymphatics, studied in five marmots, entwine major arteries of white pulp. Lymphatics vary in prominence from spleen to spleen and within a spleen.These lymphatics constitute efferent channels likely draining splenic fluid flowing within the spleen counter‐current to blood.The endothelium is irregular, thin and imperforate, beset with vacuoles and containing filaments. Its hyaloplasm is light or dark. Flap‐like inter‐endothelial cell junctions without membranous specializations are typical. Endothelial cells richly interdigitate with one another resulting in extensive, closely‐spaced intercellular junctions. Long endothelial processes extend into subjacent connective tissue.The lymphatics lie in an extracellular ground substance, continuous with that surrounding arteries and with the fibrous reticulum of white pulp. Filaments, about 100 Å in width, lie in the ground substance close upon the basal endothelial surface. The filaments appear to attach to the endothelium and run out into surrounding collagenous fibers. The collagen is abundant, occurring in thick layers around lymphatics and extending, with the ground substance, into the white pulp.Macrophages, replete with phagosomes, surround lymphatic vessels and extend processes toward them, penetrating the peri‐lymphatic connective tissue. Erythrocytes lie outside these vessels and within their lumen. Sheets of plasma cells may surround the lymphatics. Lymphocytes, in large number, are present around the lymphatics, cross their wall between endothelial cells, and lie in their lumen.
The diffuse labyrinthine endotheliodichorial placenta of the free‐tail Bat: A light and electron microscopic study
Authors: Stephens R. J. , Cabral L. J. 
Published: February 2005

AbstractIn Tadarida, the diffuse endotheliodichorial placenta is established over the parietal area of the uterus and is prominent, for an extended period of time during midgestation, both prior to and during the development of the definitive discoidal structure. A transitory yolk sac placenta precedes the establishment of the diffuse placenta. The tissues of the yolk sac are displaced from the trophoblast through collapse, and by the advance of the allantoic mesoderm. Allantoic vessels infiltrate the cords of cellular trophoblast that extend into the syncytium that, in turn, has penetrated deeply into the maternal endometrium. The syncytium progressively phagocytizes the maternal tissues, leaving the superficial maternal blood vessels and attendant pericytes intact, but destroys many of the deeper maternal vessels. Several morphological changes occur in the pericytes during the period that the superficial maternal capillaries retain their integrity, suggesting that they play an important role in maintaining these vessels which are eventually destroyed also.The cytotrophoblast is the most undifferentiated cell type throughout gestation. The syncytium, on the other hand, contains a large array of organelles that vary in concentration from one area to another within this tissue. Particular attention was paid to cytoplasmic structures potentially related to transport phenomena. Among those described are (1) coated vesicles and tubules in the syncytium at its interface with the cellular trophoblast, (2) microvilli extending from the cytotrophoblast into the syncytium some of which contained lines of pinocytotic vesicles, (3) coated vesicles along the plasma membrane of the syncytium toward the maternal tissues, and (4) pinocytotic vesicles associated with the endothelium of both the allantoic and maternal blood vessels.
The shearing properties of single osteons
Authors: Ascenzi Antonio , Bonucci Ermanno 
Published: February 2005

AbstractThe shearing strength of single human osteons has been investigated using a microtesting machine equipped with a microwave micrometer. The results Were related to the degree of calcification and the orientation of collagen fiber bundles in successive lamellae of the osteons. The following conclusions were made: (1) Osteons having a marked longitudinal spiral course of fiber bundles in successive lamellae are least able to support shearing stress. This suggests that in the other types of osteon the compactness of bone is strengthened by the lamellae having marked transversal spiral course of the fiber bundles. (2)Ultimate shearing strength and modulus of elasticity of osteons increase as calcification proceeds. (3) The shearing strength of single osteons is markedly lower than the tensile and compressive strength for samples of the same type. (4) In osteons loaded along their axis the range of elastic deformation is barely more than 1% of the length of the sample. (5) With the technical procedure used in this investigation the shearing of osteons appears to be preferentially related to the lamellar structure. In osteons loaded excentrically the portions which have slipped out have a rather irregular shape and in many cases one or two fractures occur. (6) The resistance to shearing of the cementing substance at the boundaries of the osteon may be greater than the resistance of the osteon itself.
Inclusion bodies of the epithelium of the urinary bladder in the rhesus monkey
Authors: Lucas John A. , Moser James H. , Schardein James L. 
Published: February 2005

AbstractInclusion bodies observed by light microscopy in the superficial epithelial cells of the urinary bladder of the rhesus monkey have been examined by electron microscopy. The inclusions varied from focal aggregates of fibrils in their least differentiated form to mature, paranuclear inclusion bodies 3 × 5 μ in size composed of orderly arranged fibrillar structures. The fibrils comprising the inclusions were indistinguishable from cytoplasmic tonofilaments. The significance of the inclusions remains obscure in the absence of known physiologic alteration.
Follicular histology and physiological correlates in the preovulatory hamster
Authors: Norman Reid L. , Greenwald Gilbert S. 
Published: February 2005

AbstractThe surge in plasma luteinizing hormone (LH) in the proestrous hamster begins at 1430 (Turgeon and Greenwald, '72) and this is followed by a sharp increase in follicular and interstitially derived progesterone at 1500 (Norman and Greenwald, '71). The purpose of the present study was to relate various histologic events in the ovary of the preovulatory hamster to these physiological changes, dating from the LH increase between 1430 and 1500. The earliest maturational changes in the oocyte occurred at 1600 as the nuclear membrane began to disappear, correlating with an increase in the number of pycnotic nuclei in the surrounding cumulus cells and an abrupt reduction in mitotic activity in the membrana granulosa. It is possible that the latter event is related to increased progesterone secretion by the follicle at 1500. The most rapid increase in follicular diameter occurred between 2000 and 2200 ‐ five to seven hours after the LH surge and was accompanied by a pronounced stromal edema especially of the medullary portion of the ovary. During this same time period, meiosis proceeded to the metaphase stage and the cumulus cells began to disperse to form the corona radiata. Of the eight hours required for the first meiotic division, four to six hours are spent in metaphase. The majority of animals (75%) ovulated by 0100 and all animals ovulated by 0200. Therefore, ovulation occurred 10 to 11 hours after the LH surge at 1500.
Endocrine‐like cells in human fetal lungs: An electron microscopic study
Authors: Cutz Ernest , Conen Patrick E. 
Published: February 2005

AbstractThis study of primitive bronchial epithelium in human fetuses revealed cells of distinctive ultrastructural appearance. These cells contained cytoplasmic granules similar to neurosecretory‐type granules and are termed fetal Kultschitzky‐type cells (K‐type cells) of lung. The fetal K‐type cells appear similar to certain cells in mature lungs and in other tissues that have an endocrine function. The advanced cytoplasmic differentiation and large numbers of K‐type cells in early stages of fetal development suggests that these cells might also have an important, probably endocrine function.
Adrenergic and cholinergic nerve terminals in the rat parotid gland. Electron microscopic observations on permanganate‐fixed glands
Authors: Hand Arthur R. 
Published: February 2005

AbstractThe innervation of the acinar cells of the rat parotid gland was studied using potassium permanganate fixation. Adrenergic terminals, characterized by the presence of small granular vesicles, and cholinergic terminals, containing small agranular vesicles, made close contact with the acinar cells. Both adrenergic and cholinergic terminals were observed in contact with the same cell, and subsurface cisterns of endoplasmic reticulum were found in relation to the contact areas of both types of endings. In addition, both adrenergic and cholinergic axons were found within the same Schwann cell sheath in the connective tissue spaces.
Support of normal salivary gland morphogenesis by mesenchyme derived from accessory sexual glands of embryonic mice
Authors: Cunha Gerald R. 
Published: February 2005

AbstractThe mesenchymal specificity of epithelium from the submandibular salivary gland of embryonic mice was re‐investigated employing standard epithelio‐mesenchymal separation and recombination techniques. For this purpose, tissue recombinants were constructed with epithelium and mesenchyme of the submandibular salivary gland and the seminal vesicle, preputial gland, and urogenital sinus. Salivary glands were dissected from 13‐day and the accessory sexual glands from 13– to 19–day old embryos. Tissue recombinants were grown for two to three weeks in the anterior chamber of the eye of adult male hosts.Mesenchyme from accessory sexual glands supported the growth, branching, and differentiation of epithelium from the salivary gland. After three weeks of intraocular growth, most of these heterotypic recombinants were indistinguishable from intraocular grafts of this gland. However, recombinants constructed with mesenchyme from the urogenital sinus or preputial gland exhibited an age dependent developmental response. Mesenchyme from 15‐ to 16‐day old embryos supported normal morphogenesis of the salivary gland, whereas atypical epithelial differentiation occurred when 13‐ or 14‐day old mesenchyme was employed. On the other hand, the reciprocal recombinants composed of mesenchyme from the salivary gland and epithelium derived from accessory sexual glands resulted in abortive epithelial differentiation regardless of the age of the tissues. These results suggest that the mesenchymal specificity of epithelium from the salivary gland may be related to the morphogenetic sensitivity of the heterotypic mesenchyme to androgens.
A fluorescence study on the ability of the notochord to synthesize and store catecholamines in early chick embryos
Authors: Kiray Margaret L. , Gilmoae Shirley Ann 
Published: February 2005

AbstractThe role that catecholamines play in presympathetic embryogenesis is relatively unknown. All catecholamine‐producing cells develop both the enzymes needed for catecholamine synthesis and an amine pump for the uptake of extraneous catecholamines. This investigation was undertaken to define areas which are able to produce and store catecholamines in the presympathetic chick embryo. Embryonic chicks between two and four days of incubation (stages 11 to 23) were incubated in a medium containing norepinephrine, dopa or dopa with cocaine, and treated for fluorescence according to the method of Falck and Owman. Norepinephrine uptake was considered to be evidence of the presence of an amine pump. The conversion of dopa, a nonfluorescent precursor of dopamine, to dopamine which is fluorescent was considered to be an indication that the enzyme dopa decarboxylase was present. Cocaine, an amine pump inhibitor, applied simultaneously with dopa would prevent dopamine synthesized in one site from entering other cells. It was found that the notochord was intensely fluorescent in the presence of norepinephrine. No other sites of norepinephrine uptake were seen. The notochord could also convert dopa to dopamine indicating the presence of dopa decarboxylase in notochordal cells. Similar results were obtained when cocaine was added to the incubation medium. It is concluded that the notochord is a possible site of catecholamine synthesis and storage in presympathetic chick embryos.
Juxtaglomerular granular cells and nephron autoregulation
Authors: Dunihae F. W. , Whortan E. B. 
Published: February 2005

AbstractHistological study of serially sectioned glomeruli in rat and mouse kidneys possessing different aggregates of juxtaglomerular granular cells has revealed that between 15 and 29% of glomeruli in control animals are not associated with these granular cells and that almost universal association occurs only when the granular cells are greatly increased. Thus, a significant number of nephrons in control rats are not continuously autoregulated through a local renin‐angiotensin mechanism, assuming that a lack of granules is associated with a lack of synthesis and release of renin. This association between granular cells and glomeruli is usually greater in the outer half than in the inner half of the cortex regardless of the content of granular cells; although the difference is not as great as prior reports indicate. Stimuli which either increase or decrease granularity of juxtaglomerular cells produce a similar and parallel response in both cortical regions, suggesting that control or regulation of granular cells is the same in both areas. It further suggests that the reported difference in filtration rates between superficial and deep glomeruli following sodium loading and sodium deprivation is not mediated through a differential alteration of juxta‐glomerular cell granularity. A linear regression equation was developed by which the per cent of all glomeruli associated with granular cells may be estimated from given mean juxtaglomerular granular cell indices (GCI).
Tissue cholesterol preservation: Factors associated with retention of cholesterol in rat sciatic nerve fixed for electron microscopy
Authors: Sterziag P. R. , Napolitano L. M. 
Published: February 2005

AbstractThe retention of cholesterol in rat sciatic nerve fixed in glutaraldehyde‐digitonin was investigated. Maximal retention ( >85% ) was achieved after fixation at room temperature, post‐fixation in OsO4, and dehydration in an ethanol series, 60, 80, 95, 100% (2 changes), five minutes per change. Fixing in the cold, increasing the dehydration time, changing from ethanol to acetone, or reducing the concentration of digitonin from 0.2% to 0.02%, resulted in a decrease in cholesterol retained. The greatest loss of cholesterol was found in the two changes of absolute ethanol, and therefore we recommend dehydration through 95% ethanol, followed by infiltration and embedding according to the procedure of Idelman ('64).
Effects of vitamin A deficiency on ultimobranchial tissue in the rat thyroid
Authors: Krupp Patricia 
Published: February 2005

AbstractUltimobranchial follicles in the thyroid glands of young Wistar rats, 4 to 12 weeks old, are lined by non‐keratinized stratified squamous epithe‐lium and contain desquamated cellular material. Mitoses are observed in the epithelium of these follicles which are variable in size, shape and frequency. Thyroid glands of young vitamin A deficient rats also contain ultimobranchial follicles. These follicles differ from those found in animals on a stock diet in that the stratified squamous epithelium produces keratinized concentric whorls of non‐nucleated luminal debris. After placing vitamin A deficient rats on a stock diet desquamated cellular material is no longer keratinized and resembles that seen in the control animals. Vitamin A deficient diet apparently keratinizes the stratified squamous epithelium of pre‐existing ultimobranchial follicles rather than solely having a metaplastic effect on thyroid‐like follicles of ultimobranchial tissue origin.
A three dimensional representation of the odontogenic epithelium of the rat incisor
Authors: Michaeli Y. , Greulich R. C. 
Published: February 2005

AbstractA three dimensional reconstruction of the basal end of the rat incisor, together with analytical data attesting to the reproducibility of the method is presented. The size and shape of the tooth varies little from animal to animal, while the sizes of the functional compartments are much less uniform.The odontogenic sheath is divided into three zones: Proliferation, differentiation and apposition. The proliferative zone is subdivided into two segments: The basal segment which gives rise to ameloblasts shows the highest cell production; an anterior segment located around the pulp opening which will give rise to the part of the tooth covered by cementum and has a much lower cell production.Total cell production can be obtained only in transverse sections, while mid‐sagittal sections can serve only for comparative purposes.
A scanning electron microscopic study of the ependymal surface of the third ventricle of the rabbit, rat, mouse and human brain
Authors: Bruni J. E. , Montemurro D. G. , Clattenburg R. E. , Singh R. P. 
Published: February 2005

AbstractIn all species studied, the upper two‐thirds of the third ventricle is lined by ependymal cells with a profusion of long cilia that extend into the lumen. In the rabbit, rat, and mouse, an abrupt transition to a sparsely ciliated ependymal surface occurs along the lower one‐third of the ventricular wall, at the level of the underlying ventromedial (VM) nucleus. Unique to the rat transition zone however, is a predominance of microvilli. In the human, a subtle transition to a sparsely ciliated ependymal surface occurs somewhat higher at about the level of the underlying dorsomedial (DM) nucleus. Along the upper expanse of the rabbit infundibular recess (IR) ciliary bundles are infrequent, although occasional solitary cilia are seen. The characteristic features of this region, however, are the non‐ciliated ependymal cells with their many irregular bleb or microvilli‐like surface protrusions. In contrast to the rabbit, the same region in the rat and mouse is distinguished by an irregular ependymal surface with stout bleb‐like protrusions and many single cilia. Similarly in the human, cilia become progressively fewer toward the IR. Although the non‐ciliated epen‐dymal surface in this region resembles that of the rabbit, the surface blebs and microvilli‐like protrusions are fewer in number and less prominent. The lateral walls of the third ventricle display a consistent regional variation in the morphology of the luminal ependymal surface in all species studied. Although it is not possible to establish unequivocally the nature or significance of these regional differences, the structural modifications of the ependymal surface in the region of the IR are entirely consistent with the secretory or absorptive function attributed to ependyma in this area.
The effects of hyperthyroidism on the fine structure of the zona fasciculata of the rat adrenal cortex
Authors: Moore N. A. , Callas Gerald 
Published: February 2005

AbstractChronic hyperthyroidism was induced in radiothyroidectomized and surgically thyroidectomized adult male rats by feeding a diet of 0.3–0.4% desiccated thyroid for four to ten week periods. Short term hyperthyroidism was induced in intact rats by the intraperitoneal injection of 250 μg/day of sodium levothyroxine for ten days. Adrenal glands were fixed by perfusion with 3% phosphate buffered glutaraldehyde and post‐fixed in 1% osmium tetroxide. The zona fasciculata of the adrenal glands from experimental and control animals was examined in the electron microscope. Drastic mitochondrial alterations characterized the zona fasciculata of hyperthyroid rats. Initially, mitochondria became more nearly round and contained increased numbers of paracrystalline tubular inclusions of the type described by Kjaerheim ('67) and Wheatley ('68). In more altered states many mitochondria were filled with clusters of parallel tubular cristae of varying complexity which at times enveloped islands of mitochondrial matrix and fingers of cytoplasm which projected into the mitochondrion. Aggregations of numerous mitochondria occupied much of the cytoplasm of highly altered cells. Modifications of this nature have not been described following ACTH stimulation of the adrenal cortex. This raises the distinct possibility that thyroid effects on the adrenal cortex are not entirely ACTH mediated.
Electron microscopic studies on fate of erythroblast ribosomes
Authors: Campbell Ferrell R. 
Published: February 2005

AbstractElectron microscopic observations are reported which demonstrate that ribosomes are extruded during the final stages of maturation in erythroid cells of rats and guinea pigs. Concentration of ribosomes in the cytoplasm, formation of a membrane bounded vesicle containing these ribosomes and extrusion of the vesicle are described and discussed.