bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEM studies of acellular glomerular basement membrane in human diabetic glomerulopathy
Authors: Carlson Edward C. , Surerus Kristene K. 
Published: February 2005

AbstractPrevious transmission electron microscopic studies have demonstrated glomerular basement membrane (GBM) thickening and mesangial matrix (MM) expansion in chronic stages of diabetes. It is difficult, however, to achieve an appreciation of GBM surface features and distribution of MM in planar views. In the current study, autopsy human renal cortical tissue from patients with end‐stage diabetic nephropathy were minced and rendered acellular with detergents prior to fixation, cryofracture, and preparation for light microscopic (LM), transmission electron microscopic (TEM), and scanning electron microscopic (SEM) observation in an effort to visualize extracellular materials in three dimensions.Our studies demonstrated that although diabetic glomerular changes vary widely within and between individuals, most showed alterations primarily affecting peripheral (epithelial) GBM (with MM increased but diffusely distributed), or they exhibited similar GBM changes but with variable nodular MM expansion leading ultimately to capillary occlusion. Both types showed peripheral GBM thickening and demonstrated external surface irregularities that by SEM appeared as “cauliflower‐like” lobulations. In these glomeruli, GBM lamellation or reduplication was common with internal layers frequently thrown into lumenward projections.Glomeruli with diffusely distributed MM generally showed patent capillary channels with little evidence of occlusion. By TEM, highly compact, epithelial GBMs were clearly distinguishable from the electron‐lucent MM. In these preparations the matrix was concentrated in relatively small discrete masses sometimes covered by a finely fibrillar material, which extended intermittently onto lumenal surfaces of epithelial GBMs.In more advanced stages of MM involvement, glomeruli typically exhibited smooth‐surfaced nodules that were increased at the expense of capillary surface area. By TEM, MM nodules were comprised of a meshwork of very fine (20‐Å) fibrils surrounding a variety of detergent‐resistant structures including collagenous fibrils and non‐collagenous 30‐nm circular fibrils with 16‐nm subunits. By SEM, GBM and MM nodules were not distinguishable and merged to form substantial barriers to capillary blood flow. In those capillary channels remaining patent, inwardly projecting folds and ridges were common GBM features, and frequently thin fenestrated layers, distinctly separate from epithelial GBMs, formed sieve‐like linings for the channels. These three‐dimensional observations provide unique views of the processes leading to diabetic glomerular occlusion and suggest a potential for this technique in the study of renal BM disease.
Ultrastructural and metabolic changes associated with reproductive tract atrophy and adiposity in diabetic female mice
Authors: Garris David R. , West R. Lee , Pekala Phillip H. 
Published: February 2005

AbstractThe effect of progressive, diabetes‐associated adiposity on reproductive tract structure and function was examined in 4‐ to 16‐week‐old C57BL/KsJ, control (+/?) and diabetic (db/db) mice. Uterine and ovarian tissues were analyzed by transmission electron microscopy for ultrastructural changes associated with increased intracellular lipid accumulation. In addition, the same tissues were analyzed for changes in activity of tissue lipoprotein lipase, an enzyme that hydrolyzes lipoprotein‐associated triacylglycerols and supports the cellular uptake and storage of free fatty acids. Between 8 and 16 weeks of age, intracellular lipid deposits increased dramatically in the ovarian granulosa, thecal and stromal cell populations, as well as in the uterine epithelium, of diabetic mice compared to controls. By 16 weeks of age, the lipid deposits essentially occupied the entire cytoplasmic area of both the ovarian and uterine cell types in diabetics. The basal lamina underlying the uterine epithelium was expanded in the diabetics relative to controls, and the hyperglycemic condition induced an observable increase in endometrial intercellular space that was occupied by a hyaline type of ground substance of unknown composition and origin. In association with these structural changes, both ovarian and uterine lipase activities were greatly increased in the db/db mice compared with controls. These data suggest that the structural adiposity and functional decline in reproductive tract condition of the db/db mutants are related to the enhanced cellular lipid deposition observed in this species. These changes in structural and metabolic parameters are related to the reproductive incompetence characteristic of this murine model.
Microvascular smooth muscle cell quantitation from scanning electron microscopic preparations
Authors: Gattone Vincent H. , Miller Bryan G. , Evan Andrew P. 
Published: February 2005

AbstractA morphometric method to analyze scanning electron micrographs (SEM) of microvascular smooth muscle cells (SMC) is validated using intestinal arterioles. Features easily obtained from these microvasculature preparations are counted (number of tapers and number of complete wraps in the central 87% of the vessel, which is one‐third of the vessel's circumference) or measured (vessel diameter and vessel segment length). These data allow the determination of wraps around the vessel per SMC, cell length, and cell width, which are not different from either the values as determined by circumferential examination and quantitation of the vascular segment or an alternative SEM quantitation method (Miller et al., 1986). The method described herein provides a relatively easy way to determine microvascular SMC parameters.
Isthmus and ligament interrelationships: A computerized analysis of the spatial relationships of the hinge structures in unionid mussels
Authors: Le Pennec M. , Petit H. , Jones D. L. , Davis W. L. 
Published: February 2005

AbstractA study of the isthmus and ligament in unionid mussels was undertaken employing methods specifically designed to preserve the in vivo relationships of these interrelated structures. Serial sections of the hard and soft tissues were used for two‐dimensional analysis. From these, a tridimensional computerized reconstruction was developed. Special dissections of the undisturbed isthmus were also utilized. By using such methodologies, a new description of the ligament has been developed employing such terminology as the foliated ligament and the posterior folding laminae. Similarly, for the isthmus, an anterior lyre, a pallial crest, a pallial peduncle, and a posterior lyre are described. Such entities are both morphologically and physiologically related to the shell and ligament.
Pure population of nonmonocyte derived macrophages arising in organ cultures of embryonic rat lungs
Authors: Sorokin Sergei P. , Hoyt Richard F. 
Published: February 2005

AbstractAfter fetal lungs are placed in organ culture, any macrophages arising in them must develop from precursors present at explantation. Whole pseudoglandular lungs from 20 litters of rats were set on an agar medium containing fetal bovine serum on the 14th prenatal day when the metamorphosing embryos do not yet have circulating monocytes. After a day in vitro, 10–30‐μm clusters of rounded cells began to appear in the pulmonary connective tissue. They increased in size, displayed mitotic figures, and were supplemented by additional clusters on succeeding days. Late in the second day, cells began to penetrate the visceral pleura and over the next week built up a large population outside. Histochemically, the intrapulmonary foci and emerging cells were reactive for naphthyl acetate esterase and acid phosphatase, and many were stainable for triglyceride. Within the lungs elevated acid phosphatase activity was first seen at 24 hours; it attained the level of activated alveolar macrophages 1–2 days later. After cells had been emerging 4–5 days, comparatively few clusters remained in the stroma, but some cells had crossed into the airway, to be swept along by ciliary currents. Some cultures were injected with submicronic iron oxide particles on the first day. The particles gradually concentrated within the stromal clusters, and a few emerging cells contained them. Emerged cells avidly ingested iron oxide and rhodamine‐coated latex microspheres. Cells adhering to the cultures were centers of rosette formation after exposure to sheep erythrocytes opsonized with rabbit antisheep IgG and complement factors. The explants evidently contained precursors of macrophages. Cultural conditions provoked them into dividing and exhibiting activation of lysosomes and capacity for directed migration; our experiments showed the transformed cells to be phagocytic and to have receptors associated with immune phagocytosis. The study indicates that macrophages directly derived from stem cells in embryonic lungs are similar in essentials to macrophages in adult lungs, and that this component of pulmonary immune defense is present in an occult form from almost the outset of development.
Rare case of the inferior mesenteric artery arising from the superior mesenteric artery
Authors: Kitamura Seiichiro , Nishiguchi Takahiko , Sakai Akira , Kumamoto Kenzo 
Published: February 2005

AbstractThe authors observed a variation of the inferior mesenteric artery, which arose from the superior mesenteric artery, in a 69‐year‐old Japanese male cadaver during dissection in 1984. In this case, no rudiment of the ordinary inferior mesenteric artery could be found on the abdominal aorta. There are few reports of this variation, and an extensive search of the available literature revealed only four cases, including two in Japan. Such a variation had been somewhat inadequately described as an “absence of the inferior mesenteric artery” in the previous reports, but we avoided this terminology, because all of the cases possessed an artery, which, though arising from the superior mesenteric artery instead of the abdominal aorta, had the same branches as a normal inferior mesenteric artery. Consistent with findings observed in the previous cases, the unusual inferior mesenteric artery arose as the first branch of the superior mesenteric artery, with the common trunk of both mesenteric arteries originating from the abdominal aorta at a level at which an ordinary superior mesenteric artery would arise. It is for this reason that we did not adopt another acceptable name, that is, “the common mesenteric artery,” for this variation. The variation can be explained as the result of an unusual development of the embryonic artery system, which comprises a number of ventral splanchnic arteries interconnected by longitudinal anastomotic channels to supply the primitive digestive tube.
Immunocytochemical and radioautographic evidence for secretion and intracellular degradation of enamel proteins by ameloblasts during the maturation stage of amelogenesis in rat incisors
Authors: Nanci Antonio , Slavkin Harold C. , Smith Charles E. 
Published: February 2005

AbstractIn the continuously erupting rat incisor the ameloblasts progress through distinct stages associated with the secretion and maturation of enamel. We have examined the possibility that the so‐called “postsecretory” ameloblasts of the maturation stage of amelogenesis remain biosynthetically active and are engaged in the synthesis, secretion, and degradation of enamel gene products. The ultrastructural distribution of antigenic sites for enamel proteins was studied within enamel organ cells during the early maturation stage of amelogenesis in rat incisors by using the protein A‐gold immunocytochemical technique and rabbit polyclonal antibodies developed against mouse amelogenins. All regions of amelogenesis from late secretion through the first complete modulation from ruffle‐ended to smooth‐ended ameloblasts were examined. Specific immunolabelling was found within the rough endoplasmic reticulum, Golgi saccules, secretory granules, and lysosomes of ameloblasts throughout these regions. The heaviest intracellular immunolabelling was found within secretory granules and lysosomes (multivesicular type). Quantitative analyses showed that the Golgi saccules and the multivesicular lysosomes of modulating ameloblasts were generally less immunoreactive compared to similar organelles in ameloblasts secreting the inner enamel layer. Radioautographic studies confirmed that ameloblasts of the maturation stage incorporated 3H‐leucine and 3H‐methionine and secreted labelled proteins into the enamel layer. Grain counts indicated that ameloblasts from the first ruffle‐ended band incorporated about twofold less 3H‐methionine and secreted about tenfold less labelled proteins into the enamel compared to ameloblasts secreting the inner enamel layer. The results of this study confirm that ameloblasts do not terminate biosynthesis and secretion of enamel proteins once the final layer has been deposited on the surface of the developing enamel. They continue to form and release new proteins during the maturation stage which intermix with older proteins laid down initially during the secretory stage of amelogenesis. Secretory activity for enamel proteins has been detected in ameloblasts up to at least the second ruffle‐ended phase of maturation, at which point the enamel matrix is partially soluble in EDTA.
Immunohistochemical localization of the secretory products of rat Clara cells
Authors: Manabe Toshiaki , Ikeda Hiromi , Moriya Takuya , Yamashita Koshi 
Published: February 2005

AbstractWe used proteins in rat lung lavage fluid to successfully produce an antiserum against Clara cell secretory products. When used with the immunoperoxidase method, the antiserum specifically stained cells of the bronchiolar lining, which are morphologically consistent with Clara cells, as well as a few columnar cells in the bronchial and tracheal mucosa. B‐5‐fixed lung tissue furthermore demonstrated the immunoreactive layer over the bronchiolar epithelium. The alveolar and bronchial lining layers, on the other hand, were not immunoreactive, although a trace of granular immunoreactivity was seen in the latter. It was suggested that Clara cells produce and secrete some proteinaceous materials, which are mainly localized in the bronchiolar area after secretion and are seldom transferred into the alveolar lining layer. Our antibody cross‐reacted with the Clara cells of mice, but not with those of hamsters, guinea pigs, rabbits, dogs, cats, monkeys, and man. The high degree of specificity of this antisera to Clara cells in formalin‐fixed materials should make it a valuable tool for identifying Clara cell change in non‐neoplastic lung pathology and in obtaining some insights into cell origin in neoplastic diseases.
Distribution of cell types of the islets of langerhans throughout the pancreas of the Chacma baboon
Authors: Wolfe‐Coote Sonia A. , Du Toit D. F. 
Published: February 2005

AbstractBiopsies of the pancreas head, tail, and uncinate regions of four baboons were processed for immunocytochemical (ICC) studies by using avidinbiotin‐peroxidase label for light microscopy (LM). Toluidine‐blue‐ or methylene‐blue‐stained 0.5‐μm sections of nonosmicated resin‐embedded tissue were viewed to locate areas of suitable islets. For ICC investigations, batches 10 μm apart of ten consecutive 1‐μm sections throughout ten islets from each of the three regions were immunolabelled for LM. Four slides in each batch were immunolabelled consecutively for insulin, glucagon, somatostatin, and pancreatic polypeptide, the fifth acting as one of the range of controls in each batch.The number of each of the four cell types was counted in at least ten immunolabelled islets from each of the pancreas heads, uncinate portions, and tails. The uncinate region and not the head, as in most mammals, was found to contain significantly higher numbers of pancreatic polypeptide (PP) cells and lower numbers of A (glucagon) and D (somatostatin) cells (P<.001). The PP cells occurred in clumps and not as described in other mammals as part of the mantle of A, D, and PP cells. PP and A cell numbers were significantly different for each region (P<.001), being lowest in the head for PP and in the uncinate process for A cells. D cell distribution was similar to that of the A cells whilst a significantly smaller number of B (insulin) cells was found in the tail compared with other regions (P<.001).
Thyroid development in the marsupial bandicoot, Isoodon macrourus
Authors: Johnston G. M. , Gemmell R. T. 
Published: February 2005

AbstractThe postnatal structural development of the thyroid gland of the Australian native bandicoot, Isoodon macrourus, was monitored and the onset of thyroid function (i.e., the secretion of thyroid hormones) was determined. Thyroid glands were obtained from bandicoots at days 1, 3, 11, 12, 13, 21, 25, 30, 34, 35, 39, 46, 48, 50, 59, 61, 75, 79, 83, and 163 of age and from adult animals, and the tissues were examined with the transmission electron microscope. The thyroid gland of the newborn bandicoot consisted of undifferentiated cells with no lumen. Follicles were first observed at day 12 postpartum, after which time rapid follicular growth occurred. The first signs of thyroid hormone secretion were seen at day 30 postpartum. A peak in thyroid activity seemed to occur around day 50 postpartum, and it correlated with the rapid rate of development of thermoregulatory capacity and hair development which occurred over the last 2 weeks of pouch life.
Trophoblast‐decidual cell interactions and establishment of maternal blood circulation in the parietal yolk sac placenta of the rat
Authors: Welsh Alerick O. , Enders Allen C. 
Published: February 2005

AbstractImplantation sites from rats were studied on days 6, 7, and 8 of pregnancy to determine the sequence of events in the formation of blood spaces in the trophoblast that is part of the parietal wall of the yolk sac placenta and to determine how trophoblast gains access to maternal blood. The maternal blood flowing through these spaces is the source of nutrients that reach the embryo via the visceral endoderm. Tissues were prepared for light microscopy, scanning electron microscopy, and transmission electron microscopy. Trophoblast blood spaces are derived from the lateral intercellular spaces of trophoblast cells and are present in a collapsed condition until day 8, when maternal vessels are tapped by trophoblast. These spaces than contain circulating maternal blood, and trophoblast cells reflect adaptations for metabolic exchange including thinning of trophoblast covering Reichert's membrane and the appearance of numerous fenestrations, with and without diaphragms, in the areas where trophoblast is attenuated. Between days 6 and 7 decidual cells appear to form a barrier between the maternal circulation and trophoblast. On day 7, however, decidual cell processes penetrate the residual uterine luminal epithelial basal lamina, and then the decidual cells that are juxtaposed to trophoblast undergo degradative changes that resemble apoptosis. There is condensation of cytoplasmic contents, fragmentation of the cells, and phagocytosis of the fragments by trophoblast. Some decidual cells are interposed between endothelial cells in the walls of maternal vessels as early as day 7. Trophoblast may gain access to the maternal vessels by replacing decidual cells or by direct imposition of trophoblast cell processes between endothelial cells.
Hormonal regulation of epithelial cell proliferation in the fetal mouse duodenum in vitro
Authors: Beaulieu J.‐F. , Calvert R. 
Published: February 2005

AbstractIn adult rodents, radioautographic studies have shown that cell proliferation in the small intestinal epithelium is confined to the crypts. However, before birth DNA synthesis occurs also on villi. The role of extrinsic factors in the establishment of the adult pattern of enterocyte proliferation was studied in 17‐day fetal mouse duodenal explants cultured with a completely synthetic medium. The effect of dexamethasone (30 and 300 ng/ml), thyroxine (10 nM), and insulin (125 mU/ml) on labelling indices was determined after 48 hours of culture. At the onset of the culture period close to 60% of the cells located in the first five cell positions in the intervillous areas became labelled after 4 hours of culture in presence of 3H‐thymidine; 8% of the other epithelial cells found higher in the intervillous areas and on villi were also labelled. After 48 hours of culture, well differentiated crypts have developed in all the explants cultured with or without the hormones. The addition of thyroxine or insulin did not modify the labelling indices. However, after 48 hours of culture, the presence of dexamethasone (both concentrations) significantly reduced the labelling index of the cells found over cell position 5 but had no effect on the labelling index of cells located at the bottom of the crypts. When labelling index was determined for each cell position in the crypts at the end of the culture period, it appeared that dexamethasone (300 ng/ml) had no effect thereon for the first five cell positions but had a significant influence on the transitional zone from cell position 6 through 15. In controls, the labelling index fell to 5% for cell position 15, while it reached the same level in position 9 in presence of the hormone. These results indicate that during late fetal life in rodents, glucocorticoids contribute to compartmentalization of the proliferative zone at the bottom of the duodenal crypts and thus might be responsible for the acquisition of the adult proliferative pattern.
Structural organization of the vertebral artery in the giraffe (Giraffa camelopardalis)
Authors: Kimani James Kirumbi 
Published: February 2005

AbstractVertebral arteries in the giraffe were removed and their structural organization was studied with light microscopy. It has been shown that the caudal segment of the vertebral artery extending to the level of the seventh cervical vertebra has a largely elastic structure, while the cranial segment has a muscular structure. The transition of the arterial wall normally occurs between the seventh and fifth cervical vertebral levels, and involves diminution of elastic tissue in the luminal portion of the tunica media and simultaneous increase of the smooth muscle content. The smooth muscle cells in the cranial portion show a clustered arrangement consisting of several smooth muscle fibres. The individual clusters are separated by connective tissue septa from which finer strands extend to surround individual muscle fibres. It is suggested that the vertebral and carotid arteries though found in the neck have a different structural organization, which, in turn, may imply that the two blood vessels are subjected to different haemodynamic demands. The findings of this study therefore render further support to the statement that the largely muscular structure of the common carotid artery in the giraffe may be related to the unique cerebral haemodynamics of this animal, rather than being a common feature of the blood vessels situated in the neck. A corollary to this suggestion is the fact that, in the giraffe, as in most other Artiodactyls, the vertebral blood does not participate in the supply of cephalic structures because it is confined to the cervical region by the pressure barrier in the carotid‐vertebral anastomosis.