bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive tract abnormalities in rats treated neonatally with DES
Authors: Ennis Bruce W. , Davies Jack 
Published: February 2005

AbstractNeonatal female Sprague‐Dawley rats were given daily injections of 3 μg diethylstilbestro (DES) for 5 days beginning within 24 hours of birth. Some of these rats were ovariectomized between the 15th and 18th postnatal days, and on the 60th postnatal day were given daily injections of 3 μg estradiol for 1, 3, or 5 weeks. Intact rats were sacrificed at 60, 95, or 130 days. The morphology of the upper vagina, cervix, and lower uterus was examined by light and scanning electron microscopy. Two abnormalities resulting from neonatal DES exposure were found. The first was squamous metaplasia observed in the uteri of rats given DES and later exposed to exogenous or endogenous estrogen. Metaplasia was seen in both the luminal and glandular epithelium. The longer the rats were exposed to exogenous or endogenous estrogen, the more extensive was the metaplasia. The second was a gross morphologic abnormality seen in all rats given DES regardless of any later treatment. That part of the cervix that protrudes into the cranial limit of the vagina was absent and, thus, a vaginal fornix was nonexistent.Previous investigations have emphasized abnormalities of the lower reproductive tract. The present study indicates that the upper reproductive tract also must be considered in investigations of the effects of hormones administered to neonates.
Arteries and veins of the normal dog lung: Qualitative and quantitative structural differences
Authors: Michel René P. 
Published: February 2005

AbstractAs a necessary preliminary step to the study of pulmonary hypertension and edema, the structure of the pulmonary vasculature of seven normal dogs was examined in detail to distinguish arteries and veins. For light microscopy and morphometry, the left lung was injected from the arterial and venous sides with pigmented gelatin masses of different colors. The right lung was fixed for electron microscopy. The percentage of medial muscle thickness of arteries was greater (P < 0.05) than that of veins, for vessels over 200 μm diameter. Smooth muscle cells extended more peripherally into arteries (including in vessels less than 50 μm) than into veins. The larger arteries were elastic or transitional in type, whereas larger veins were muscular. The arteries branched with the airways. Fifty percent of arteries under 50 μm and more than 50% of veins under 200 μm were surrounded by alveoli. Muscular arteries had a thick media between distinct internal and external elastic laminae, whereas veins had no internal lamina but had a thin media separated from a thick adventitia by an external elastic lamina. By electron microscopy, the muscular arteries had tightly packed smooth muscle cells with few myoendothelial junctions; the venous smooth muscle cells were arranged loosely, and more numerous myoendothelial junctions were seen. No definite differences were noted between nonmuscular arteries and veins. The functional implications of these morphological findings (differential reactions to pharmacological agents, distensibility of pulmonary arteries and veins, and responses of small vessels to alveolar pressure) are discussed.
Phasic secretion by follicular cells of the bat adenohypophysis during the prearousal period of their annual life cycle
Authors: Nunez Eladio A. , Gershon Michael D. 
Published: February 2005

AbstractThe fine structure of the follicular (nongranulated) cells of the adenohypophysis of the bat was examined at different periods of the annual life cycle. Follicular cells were found in all regions of the pars distalis of both active and hibernating bats. Throughout the active phase of the life cycle and during most of the hibernating period, the structure of follicular cells is unchanged. Toward the end of hibernation, however, striking ultrastructural changes occur. The most obvious of these alterations is the appearance in follicles of dense rodshaped bodies within the follicular luminal space. Just prior to arousal, the rodlike bodies become much wider and appear more as paracrystalline aggregates of dense material. Images indicate that the dense rod‐shaped bodies are packaged in vesicles in the cytoplasm of the follicular cells. The fusion of the membrane of filled vesicles with the plasma membrane of the follicular cell results in the release of their dense rod‐shaped bodies into the follicular lumen by exocytosis. These cyclic ultrastructural changes indicate that follicular cells have a phasic secretory activity.
Neuronal changes induced by neonatal hypothroidism: An ultrastructural study
Authors: David S. , Nathaniel E. J. H. 
Published: February 2005

AbstractThe postnatal development of the neurons of the cuneate nucleus was examined ultrastructurally in euthyroid and hypothyroid rats from birth to the sixth postnatal week. In the euthyroid animals, the neurons at birth displayed mild nuclear invaginations and a scanty cytoplasm with few organelles. By 2 weeks, there was a considerable increase in Nissl bodies. At 3 weeks, the neurons contained short lamellar arrays of endoplasmic reticulum. Between 3 and 6 weeks there was a reduction in the Nissl substance. In the hypothyroid animals, although the sequence of maturational changes generally resembled that of the controls, a number of differences were noted. The neurons at 1 week displayed dilations of perinuclear space, rough endoplasmic reticulum, Golgi complexes, and mitochondria. At 4 weeks both perikaryon and myelinated axons contained glycogen. Several neurons with cytoplasmic inclusions considered to be nonfunctional RNA were seen. The 6‐week hypothyroid neuron exhibited large, clear, cytoplasmic vacuoles associated with a drastic reduction in cytoplasmic organelles. Presynaptic terminals showed a 50% reduction in mitochondrial numbers associated with the presence of glycogen granules. Three changes observed in neurites in all the age groups included: (1) large accumulation of glycogen in presynaptic terminals; (2) clear vacuoles; and (3) the presence of numerous lamellar bodies within reactive axons. Aberrant myelination, such as a single myelin sheath enclosing multiple processes, and instances of collapsed and redundant myelin were encountered.
Ultrastructure of cultured atrial cardiac muscle cells from adult rats
Authors: Moses R. L. , Claycomb William C. 
Published: February 2005

AbstractAtrial cardiac muscle cells enzymatically isolated from adult rats were maintained in culture for 0–17 days and examined by transmission electron microscopy (TEM). Cells were stained with conventional TEM stains as well as with osmium ferrocyanide and tannic acid. Our results show that cultured adult atrial cells are capable of in vitro ultrastructural reorganization and possess differentiated ultrastructural characteristics including specific atrial granules, sarcomerically arranged myofilaments, appropriately organized sarcoplasmic reticulum (both junctional and nonjunctional), and intercalated disc components. In addition, the cultured atrial cells also posses rare, but ultrastructurally typical, elements of the transverse tubular system. These can be identified on the basis of size, location, association with internal junctional sarcoplasmic reticulum, and accumulation of extracellular tracer. Atrial muscle cells are capable of reestablishing a myotypic ultrastructure, although they have a considerably less complex and organized in vitro ultrastructure than similarly cultured adult ventricular myocytes. This lessened in vitro ultrastructural specialization is in accord with the in vivo comparative ultrastructure of atrial vs. ventricular myocytes.
Microdissection by ultrasonication: Porosity of the intestinal epithelial basal lamina
Authors: McClugage Samuel G. , Low Frank N. 
Published: February 2005

AbstractThe porosity of the epithelial basal lamina of normal rat intestine was studied by SEM. Epithelial removal was accomplished by prolonged fixation of tissue samples in OsO4 or immersion in aqueous H3BO3, followed by dehydration in acetone and microdissection by ultrasonic vibration. The underlying basal lamina of intestinal epithelium reveals numerous pores of variable size. These pores are more numerous in small than in large intestine and penetrate the entire thickness of the basal lamina. Within the basal lamina overlying lymph nodules, they are numerically increased. Their occurrence is evident in fixed and unfixed, sonicated and unsonicated tissue samples. Microprojections of epithelial cytoplasm are often observed within these pores. The results of this study suggest that migrating cells or epithelial‐cell processes induce pore formation in epithelial basal laminae and that these pores may be eventually repaired.
A comparative study of osteoblasts: In situ versus isolated specimens
Authors: Ries William L. , Gong Joseph K. , Sholley Milton M. 
Published: February 2005

AbstractOsteoblast and osteoclasts are known to adhere tenaciously to bone surfaces even when the fibrous periosteal covering is removed. Brushsmear isolates and in situ, whole bone mounts of the osteogenic periosteum on the inner and outer calvarial tables of young adult rats were examined at the light microscopic level after exposing the cells by removing the fibrous periosteum. Based on staining, enzymatic activity, and overall morphology, most of the cells could be classified as osteogenic in nature. However, detailed analysis revealed that some cells exhibited certain unique morphologic appearances that suggested the existence of subpopulations or variant forms of the conventional or prototypic osteoblast. Three variant forms were the large nucleate, small nucleate, and multinucleate osteoblast‐like cells, the latter with nuclear numbers ranging from 2–10. The finding of all such forms in smears, short‐term cell cultures, and in situ specimens greatly lessened the probability that the unusual forms were artifactual. Phase contrast microscopic studies and sectioning of cellular isolates for study at both the light and electron microscopic levels provided additional support for the existance of the multinucleate osteoblast‐like cell. The small size of these osteoblast‐like subpopulations and the orientation of the cells to the commonly used plane of section of most histologic bone specimens, particularly with the multinucleate type, could explain why they had escaped earlier detection.
Morphological evidence of reduced bone resorption in the osteosclerotic (oc) mouse
Authors: Seifert Mark F. , Marks Sandy C. 
Published: February 2005

AbstractOsteopetrosis, a metabolic bone disease characterized by a generalized sclerosis of the skeleton, is inherited as an autosomal recessive in a number of mammalian species. The pathogenesis of congenital osteopetrosis is mediated by a reduction in bone resorption as a result of decreased osteoclast function. This hypothesis is based on both functional and structural evidence of reduced bone resorption in all mutations examined to date. The present study examined the histology of cartilage and bone, the ultrastructure of osteoclasts, and the morphology of mineralized bone surfaces in a lethal osteopetrotic mutation, the osteosclerotic (oc) mouse.Histologically, epiphyseal cartilage growth plates, especially the hypertrophic zone, are markedly thickened in oc mice and metaphyses contain excessive osteoid, features characteristic of rickets. Transmission electron microscopy revealed that less than one‐quarter of osteoclasts in oc mice demonstrated evidence of ruffled border formation compared with three‐quarters of the osteoclasts in normal littermates. In mutants, ruffled borders were less elaborate and cytoplasmic processes penetrated into bone surfaces, suggesting that bone may be removed by mechanical rather than by enzymatic means. There was little morphological evidence of cartilage degradation and broad laminae limitantes persisted in mutants. Mineralized surfaces that undergo resorption in normal mice showed no evidence of bone resorption by scanning EM in mutants.The presence of a rachitic condition, the observations of reduced bone resorption, and the possible contribution of undermineralized matrices to decreased bone resorption are charcteristics of the osteosclerotic mutation which suggest that it is a unqiue csteopetrotic mutant in which to study both the development and regulation of skeletal metabolism.
Endothelial mitosis during the initial stages of corpus luteum neovascularization in the cycling adult rat
Authors: Gaede S. D. , Sholley M. M. , Quattropani S. L. 
Published: February 2005

AbstractThe initial stages of neovascularization of the corpus luteum were studied in cycling adult rats using light‐microscopic autoradiography. The aim of this analysis was to determine whether endothelial mitosis is a factor in this vascular growth and whether there are differences in the amount of mitotic activity in various regions of the ovary. Ovaries were examined at two time intervals: 1–2 hr and 7–8 hr following ovulation. Animals received an intraperitoneal injection of tritiated‐thymidine 20 min prior to perfusion fixation of the ovaries. Autoradiographic demonstration of tritiated‐thymidine labeling in endothelial nuclei was considered an indication of DNA synthesis preceding mitosis. The percentage of labeled endothelial cells in the ovaries at both time intervals varied according to the region of tissue examined and the stage of differentiation of that region. Stromal vessels were less heavily labeled than thecal vessels. Thecal vessels surrounding growing follicles were more heavily labeled than those surrounding atretic follicles. The heaviest labeling was seen in the developing corpora lutea 7–8 hr following ovulation. Minimal labeling was evident in the corpora lutea which were formed in previous cycles. A regional difference was also detected in the ovarian mesothelium. The portion of the mesothelium overlying ovulated follicles and developing corporalutea had the greatest percentage of labeled cells. The major findings of this study were: (1) endothelial mitosis was elevated in the initial stages of luteal neovascularization; (2) the heightened endothelial labeling was confined to specific regions of the ovary; and (3) mesothelium in close proximity to the developing corpora lutea also displayed heightened DNA synthesis.
Restriction to endogenous plasma proteins by a fenestrated capillary endothelium: An ultrastructural immunocytochemical study of the choriocapillary endothelium
Authors: Pino Richard M. 
Published: February 2005

AbstractThe choriocapillaris is a fenestrated capillary bed in the eye that restricts the egress of exogenous tracer molecules with Einstein‐Stokes radii (ESR) ≥3.2 nm. The present study examined the permeability of its endothelium to the endogenous plasma proteins albumin (ESR, 3.5 nm) and IgG (ESR, 5.5 nm) using ultrastructural immunocytochemistry. Reaction product indicative of the localization of albumin and IgG (using Fab‐HRP conjugates) was high in the capillary lumen. In contrast, neither protein was localized extravascularly in Bruch's membrane, in endothelial vesicles, or in endothelial channels. The restriction was evident at the luminal side of the diaphragms spanning fenestrae, vesicles, and channels, and at the luminal front of cell junctions. In marked comparison, high levels of reaction product were localized in the extravascular space surrounding mucosal capillaries in the ileo‐jejunum. Observations of tissue subjected to postembedment staining using a protein A‐gold method were similar. These findings demonstrate for the first time the restriction of endogenous plasma proteins by a capillary endothelium identical in morphology to that of other vascular beds proven to be permeable.
Glycoconjugate localization with lectin and PA‐TCH‐SP cytochemistry in rat hypophysis
Authors: Nakagawa Fukuo , Schulte Bradley A. , Spicer Samuel S. 
Published: February 2005

AbstractGlycoconjugates were localized by light microscopy with lectin‐peroxidase conjugates and by electron microscopy with the periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) sequence in immunocyto‐chemically or morphologically identified cell types in rat pituitary. Lectin histochemistry demonstrated sialic acid and glycoconjugates with N‐glycosidically linked oligosaccharides in gonadotrophs, thyrotrophs, and corticotrophs. Galactose penultimate to sialic acid was observed mostly in gonadotrophs. The terminal galactose‐N‐acetylgalactosamine disaccharide was detected in a few gonadotrophs and in a moderate number of mammotrophs. Fucose was localized in only corticotrophs with two fucose‐binding lectins and in thyrotrophs with another. Several different monosaccharides were seen in glycoconjugates in melanotrophs and in Herring bodies. Melanotrophs displayed heterogeneous staining with fucose‐binding lectins. A small number of nonsecretory cells were also visualized in the pars distalis by virtue of their glycogen content. PA‐TCH‐SP staining revealed complex carbohydrates in secretory granules and some Golgi cisternae in all types of hormone‐producing cells in the pars distalis except for the somatotrophs. Melanotrophs of pars intermedia exhibited stained secretory granules and irregular dense bodies containing a stained meshwork. Corticotrophs of the pars distalis lacked the latter bodies, although they from the same glycoprotein precursor hormone as melanotrophs. Lectin conjugates and the PA‐TCH‐SP sequence stained some groups of secretion granules in Herring bodies, possibly representing vasopressin‐containing granules as well as other cell types in the pars nervosa.
Effects of B‐retinyl acetate on human breast epithelium in explant culture
Authors: Strum Judy M. , Resau James H. 
Published: February 2005

AbstractExplants of human breast (obtained aseptically from ten women ages 18–37) were examined and the vitamin A compound B‐retinyl acetate was tested (at 3 × 10−5 and 3 × 10−6 M) for its effects on the fine structure and growth of the epithelium. In the absence of B‐retinyl acetate, cells growing out from the explant (outgrowth cells) underwent squamous metaplasia, began to accumulate many intermediate filaments (tonofilaments), and revealed large desmosomes after 2 weeks in culture. In the presence of either concentration of B‐retinyl acetate, the epithelial cells were largely prevented from undergoing squamous metaplasia. The glandular epithelium inside the explant maintained a typical secretory appearance for 2 weeks in control cultures (without the retinoid) and then began to show increased numbers of lysosomes and a loss of secretory granules. These glandular epithelial cells did not undergo squamous metaplasia, but they contained increased numbers of intermediate filaments. In contrast, glandular epithelium cultured in either concentrations of B‐retinyl acetate appeared secretory for as long 6 weeks in culture, and intermediate filaments were not obvious. Autoradiographs demonstrated that both concentrations of B‐retinyl acetate inhibited cell division in the outgrowth epithelium and in the (internal) glandular epithelium. The ability of B‐retinyl acetate to reverse squamous metaplasia in the outgrowth cells was also tested. Out growth cells reversed to a more normal ductlike appearance after 6 weeks culture in standard medium followed by only 1 week in 20 μg/ml B‐retinyl acetate. After 7 weeks in standard medium and 1 week in 10 μg/ml B‐retinyl acetate, the cells showed a partial reversal of the squamous metaplasia.
Endocytosis in the uterine luminal and glandular epithelial cells of mice during early pregnancy
Authors: Tung Hai‐Nan , Parr Earl L. , Parr Margaret B. 
Published: February 2005

AbstractWe have localized horseradish peroxidase (HRP) in the mouse uterus after intravenous administration on days 1 and 5 of pregnancy in an effort to understand how serum proteins reach the uterine lumen. Direct movement of HRP into uterine and glandular lumina was blocked by the epithelial tight junctions on both days. In luminal and glandular epithelial cells at both times, HRP was localized in endocytic vesicles along the basolateral membranes, multivesicular bodies (mvb), elongated dense bodies below the nucleus (bdb), and many small vesicles near the apical surface of the cells. The uptake of HRP was most extensive in the luminal epithelium on day 1: the number of tracer‐containing apical vesicles and bdb was largest, and there were also clusters of vesicles containing the tracer above the nucleus. Acid phosphatase was localized on day 1 in mvb and bdb in both cell types, indicating that these structures are lysosomes. It appeared that HRP followed two pathways after basolateral endocytosis by the epithelial cells: it was transported to the apical region of the cells, where it was present in small vesicles that may release their contents into the uterine or glandular lumina, or it was transported to lysosomes.To investigate whether macromolecules may be transported from the uterine lumen to the stroma, we also studied endocytosis at the apical pole of luminal epithelial cells after intraluminal injection of HRP. There was no detectable uptake of HRP from the lumen on day 1, and no tracer was detected in the intercellular spaces or basement membrane region. On day 5, a large amount of HRP was taken up from the lumen into apical endocytic vesicles, mvb, and dense bodies, but tracer was not present in the Golgi apparatus, lateral intercellular spaces, or the basement membrane region at the times studied. These observations indicate that there was no transport of luminal macromolecules to the uterine stroma on day 1, while the possibility of transport on day 5 requires further study.
Blastocyst implantation in the chinese hamster (Cricetulus griseus)
Authors: Blankenship Thomas N. , Given Randall L. , Parkening Terry A. 
Published: February 2005

AbstractEmbryonic development of the Chinese hamster (Cricetulus griseus) was studied from the onset of implantation to the formation of the parietal yolk sac placenta. Implantation began on day 6 of pregnancy, when the embryo became fixed to the uterine luminal epithelium. At this time there was no zona pellucida, and microvilli of the trophoblast and uterine epithelium were closely apposed. Stromal cells immediately adjacent to the implantation chamber began to enlarge and accumulate glycogen. By day 7 the mural trophoblast penetrated the luminal epithelium in discrete areas. The trophoblast appeared to phagocytize uterine epithelial cells, although epithelium adjoining the points of penetration was normal. In other areas nascent apical protrusions from the uterine epithelium indented the surface of the trophoblast. The epiblast had enlarged and both visceral and parietal endoderm cells were present. The well‐developed decidual cells were epithelioid and completely surrounded the implantation chamber. On day 8 the uterine epithelium had disappeared along the mural surface of the embryo. The embryonic cell mass was elongated and filled the yolk sac cavity. Reichert's membrane was well developed. The uterine epithelial basal lamina was largely disrupted, and the trophoblast was in direct contact with decidual cells. Primary and secondary giant trophoblast cells were present and in contact with extravasated maternal blood. The mural trophoblast formed channels in which blood cells were found in close proximity to Reichert's membrane. Decidual cells were in contact with capillary epithelium and in some cases formed part of the vessel wall. Structural changes occurring in the embryo and endometrium during implantation in the Chinese hamster are described for the first time in this report and are compared to those described for some other myomorph rodents.