bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the chorqid plexus anlage and supraependymal structures in the fourth ventricular roof plate of human embryos: Scanning electron microscopic observations
Authors: Otani Hiroki , Tanaka Osamu 
Published: February 2005

AbstractThe developing anlage of the choroid plexus and supraependymal structures in the fourth ventricular roof plates of nine normal human embryos ranging from Carnegie stages 14 to 19 were investigated with scanning electron microscopy. In the human embryos at stage 18, the first semimacroscopic choroidal anlage developed in the form of bilateral evaginations that ran dorsomedially and caudally from the bilateral corners of the rhombencephalon. The anlage became evident with even smaller and parallel ridges in the embryo at stage 19. Embryos at earlier stages exhibited surface membrane modifications such as convexity, microvilli, cilia, and spherical protrusions at the middle one‐third of the rhombencephalon, which corresponded to the future choroidal anlage region.Two morphologically different groups of supraependymal cells (SE cells) were elucidated throughout the stages examined. Type 1 SE cells has spindle or teardrop‐like bodies, frequently with one or more long cy‐toplasmic processes. Type 2 SE cells were globular, with numerous fine pseudopodial processes. Type 1 SE cells were distributed mainly at the future choroidal anlage regions or on the anlage itself and were less frequently located at the rostral end of the roof. We found no general pattern in the distribution of type 2 SE cells. Supraependymal fibers (SE fibers) wete seen as fine processes that were distributed similarly to type 1 SE cells and extended transversely for a long distance.
Three‐dimensional canine renovascular structure and circulation visualized in situ with the dynamic spatial reconstructor
Authors: Bentley Michael D. , Hoffman Eric A. , Fiksen‐Olsen Mary J. , Knox Franklyn G. , Ritman Erik L. , Romero J. Carlos 
Published: February 2005

AbstractThe dynamic spatial reconstructor–a unique, high speed, volume‐scanning, X‐ray computed tomographic imaging system–was utilized to examine canine renovascular anatomy and renal circulation in situ. In each of the four kidneys examined in this study initial scans were done during bolus injections of angiographic contrast material into the renal artery. A subsequent scan was then performed following an injection of methyl‐methacrylate‐based casting compound that had been contrast enhanced with ethiodol. After the scans, each kidney was removed, and its parenchyma was digested in potassium hydroxide to expose the vascular cast. Comparison of casts with their reconstructed images and with images obtained during injection of contrast material showed that interlobar arteries and occasionally arcuate arteries could be clearly detected. Although discrete vessels less than 1 mm in diameter could not be resolved, dynamic changes in parenchymal distribution of density during passage of contrast material allowed interpretation of flow through the multiple capillary beds of the kidney. Such analysis indicated that maximal density was in the outer‐middle zone of the cortex throughout the duration of the scan. Analysis of artery‐to‐vein transit time showed arrival of contrast material in the renal vein as soon as 3 sec, and continuation for longer than 8 sec, after the renal artery bolus. In conclusion, renal circulation in the dog can be discretely visualized with the dynamic spatial reconstructor up to the level of the arcuate arteries; however, capillary flow as a whole can be followed through the cortex, and the results suggest the presence of both rapid and slow components of peritubular circulation.
Transitional cells at the junction of seminiferous tubules with the rete testis of the rat: Their fine structure, endocytic activity, and basement membrane
Authors: Hermo Louis , Dworkin Joel 
Published: February 2005

AbstractTransitional cells line the intermediate region of rat seminiferous tubules situated between the rete testis and the seminiferous epithelium proper. These tall elongated cells orient themselves in a downstream direction and converge on one another distally in the lumen of the rete testis where they form a distinct papillalike structure through which a narrow patent lumen is apparent. In addition to widely dispersed Golgi apparatus and mitochondria, these cells contain an abundance of microtubules, cisternae of endoplasmic reticulum, and a distinct lobulated nucleus showing clumps of chromatin and a prominent nucleolus.The endocytic activity of these cells was examined by employing adsorptive (cationic ferritin, concanavalin A ferritin) and fluid‐phase tracers (native ferritin, horseradish peroxidase‐colloidal gold complex, and concanavalin A ferritin in presence of a methyl‐D‐mannoside). Such tracers were injected separately into the lumen of the rete testis, and the animals were killed at 2, 5, 15, and 30 min and 1, 2, and 6 hr after injection. At 2 min, both adsorptive and fluid‐phase tracers were found within coated and uncoated pits of the apical plasma membrane of these cells as well as in large, subsurface, uncoated spherical, C‐shaped, and tubular membranous elements. At 5 min the tracers were seen in endosomes of different sizes; while at 15 min and 30 min, pale and dense multivesicular bodies of small and large sizes, respectively, were labeled. At 1‐hr and longer time intervals secondary lysosomes became labeled. While both fluid‐phase and adsorptive tracers followed the same pathway and fate, binding to the apical and lateral plasma membranes of the transitional cells and to the membrane delimiting coated and uncoated pits was observed only with the adsorptive tracers. These results demonstrate that the transitional cells are actively involved in both fluid‐phase and adsorptive endocytosis, which may play an important role in modifying the composition of the luminal fluid.The transitional cells of the distal zone of the intermediate region rest on an elaborate basement membrane (BM) complex which includes a thin BM immediately underlying these cells, a thick distal layer of BM, and strands of BM spanning the distance between the two in the form of a loose anastomotic network. Use of antisera against heparan sulfate proteoglycan, laminin, and type IV collagen revealed the presence of all three components within all areas of the BM complex. In the meshes of the anastomotic BM network, extracellular vesicles were observed. Vesicles of similar size and appearance were also noted in the basal region of the transitional cells as well as in their basal‐foot‐like processes which extended deep into the meshes of the anastomotic network. While such extracellular vesicles may be derived from the transitional cells, their functional significance is as yet unclear.
Fine structure of the ventral and dorsal lobes of the prostate in the young adult syrian hamster, Mesocricetus auratus
Authors: Toma Jean G. , Buzzell Gerald R. 
Published: February 2005

AbstractThe normal ventral and dorsal prostatic lobes of the young adult Syrian hamster were examined at the light and electron microscopic levels. Each lobe is composed of branched tubular secretory units separated from each other by loose interacinar connective tissue and draining into the urethra. The lumen of each acinus is lined by a simple epithelium composed of columnar secretory cells with occasional small basal cells. The epithelial layer, with the thin underlying lamina propria, forms a mucosa that is often highly folded. The whole acinus is bounded by a thick muscular stroma.In each of the ventral lobes, there are three main ducts, each one formed of tubular branched tributary secretory units. The walls of the secretory acini are moderately folded. Microvilli dominate the lumenal surface of the secretory epithelial cells. The Golgi complex is very extensive and shows dilated cisternae and secretory vesicles and vacuoles of various sizes. Membrane‐bounded secretory granules populate the Golgi and apical areas and are released into the acinar lumen by exocytosis. The rough endoplasmic reticulum is dispersed throughout the cytoplasm, except in the region of the Golgi apparatus.In each of the dorsal lobes, there are several main tubular ducts that open into the urethra. Both proximal (ductal) and distal portions of the glandular tree are secretory in nature. Microvilli and cytoplasmic bulges and blebs dominate the lumenal surface of the secretory cells. The cells are also characterized by highly dilated cisternae of rough endoplasmic reticulum. The secretory cells show heterogeneity in the degree of dilation and distribution of rough endoplasmic reticulum, and this heterogeneity may reflect location in the glandular tree. Large dilated cisternae with irregular outlines are common in the basal portion of some cells, mainly those of the distended proximal (ductal) portions of the acini. The more highly folded distal portions of acini show smaller regular cisternae distributed throughout the cytoplasm. The Golgi complex is poorly to moderately developed, and membrane‐bounded secretory granules are absent or sparse. Apocrine secretion predominates in the dorsal lobe.
Dibutyryl cyclic AMP modulation of gap junctions in SW‐13 human adrenal cortical tumor cells
Authors: Murray Sandra A. , Taylor Floyd 
Published: February 2005

AbstractCultured human adrenal cortical adenocarcinoma cells (SW‐13) form a confluent monolayer of epithelial like cells when seeded into culture flasks. Following a 24–48 hr nonmitotic period, cells begin to divide and become confluent within a week after seeding at 5×104 cells/cm2. The SW‐13 cells were exposed to dibutyryl cyclic AMP (DbcAMP), cyclic AMP (cAMP), sodium butyrate, and adrenocorticotropin (ACTH). The rate of SW‐13 cell proliferation was measured with a DNA microfluorometric assay, as well as by procedures measuring the incorporation of 3H‐thymidine. In addition, following administration of ACTH and DbcAMP, the fractional area of membrane covered by gap junctions was quantitated with freeze‐fracture electron microscopic techniques. Dibutyryl cyclic AMP at a concentration of 1 × 10−3 M decreased the growth rate of the cell population. There was a corresponding increase in the fractional area of gap junctions found on the cell membrane in 96‐hr DbcAMP‐treated cultures. ACTH (40 mU/ml) exposure failed to produce an increase in the fractional area of gap junctions or to alter the rate of cell proliferation. From these data it can be suggested that elevations in cAMP levels within the cell can be related to both the proliferation of gap junctions and the decrease in cell proliferation in the SW‐13 tumor cell.
Morphometry of feline neutrophil granule genesis
Authors: Fittschen C. , Parmley R. T. , Bishop S. P. , Williams J. C. 
Published: February 2005

AbstractDuring neutrophil granule genesis, the formation of primary granules is generally thought to be limited to the promyelocyte stage; whereas synthesis of secondary granules is thought to occur only at the myelocyte stage. This hypothesis was tested morphometrically in feline neutrophils that are known to contain both granule types. Marrow specimens obtained from six cats were stained with peroxidase for identification of neutrophil primary granules and counterstained with periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) for identification of secondary granules. By regression analysis using arithmetic models, numbers of cytoplasmic granules in 311 cells were correlated with the degree of nuclear chromatin condensation, which was shown to be an adequate parameter for cell maturation. Promyelocytes and myelocytes had similar mean numbers of peroxidase‐positive granules per unit area. A significant increase (p ≤ 0.0001) in the numbers of peroxidase‐positive granules was noted between the metamyelocyte and the mature neutrophil stage, despite the lack of peroxidase activity in endoplasmic reticulum and Golgi lamellae. By contrast, a significant increase of peroxidase‐negative granules between the metamyelocyte and the mature neutrophil stage was not clearly established with these methods. The increase in peroxidase‐positive granules may indicate continued production of peroxidase‐containing granules and/or redistribution of peroxidase among lysosomal organelles in late feline neutrophils.
Reticular meshwork of the spleen in rats studied by electron microscopy
Authors: Saito Hiroaki , Yokoi Yukio , Watanabe Sumio , Tajima Junko , Kuroda Heroyuki , Namihisa Toshihiko 
Published: February 2005

AbstractThe reticular meshwork of the rat spleen, which consists of both fibrous and cellular reticula, was investigated by transmission electron microscopy. The fibrous reticulum of the splenic pulp is composed of reticular fibers and basement membranes of the sinuses. These reticular fibers and basement membranes are continuous with each other. The reticular fibers are enfolded by reticular cells and are composed of two basic elements: (1) peripheral basal laminae of the reticular cells, and (2) central connective tissue spaces in which microfibrils, collagenous fibrils, elastic fibers, and unmyelinated adrenergic nerve fibers are present. The basement membranes of the sinuses are sandwiched between reticular cells and sinus endothelial cells and are composed of lamina‐densalike material, microfibrils, collagenous fibrils, and elastic fibers. The presence of these connective tissue fibrous components indicates that there are connective tissue spaces in these basement membranes. The basement membrane is divided into three parts: the basal lamina of the reticular cell, the connective tissue space, and the basal lamina of the sinus endothelial cell. When the connective tissue space is very small or absent, the two basal laminae may fuse to form a single, thick basement membrane of the splenic sinus wall. The fibrous reticulum having these structures is responsible for support (collagenous fibrils) and rebounding (elastic fibers).The cells of the cellular reticulum–reticular cells and their cytoplasmic processes, which possess abundant contractile microfilaments, dense bodies, hemidesmo‐somes, basal laminae, and a well‐developed, rough‐surfaced endoplasmic reticulum, and Golgi complexes, which are characteristic of both fibroblasts and smooth muscle cells–are considered to be myofibroblasts. They may play roles in splenic contraction and in fibrogenesis of the fibrous reticulum. The contractile ability may be influenced by the unmyelinated adrenergic nerve fibers that pass through the reticular fibers.The three‐dimensional reticular meshwork of the spleen consists of sustentacular fibrous reticulum and contractile myofibroblastic cellular reticulum. This meshwork not only supports the organ but also contributes to a contractile mechanism in circulation regulation, in collaboration with major contractile elements in the capsulo‐trabecular system.
Visualization of the large heparan sulfate proteoglycan from basement membrane
Authors: Laurie G. W. , Inoue S. , Bing J. T. , Hassell J. R. 
Published: February 2005

AbstractKleinschmidt spreading, negative staining, and rotary shadowing were used to examine the large form of (basement membrane) heparan suifate proteoglycan in the electron microscope. Heparan suifate proteoglycan was visualized as consisting of two parts: the core protein and, emerging from one end of the core protein, the glycosaminoglydan side chains. The core protein usually appeared as an S‐shaped rod with about six globules along its length. Similar characteristics were observed in preparations of core protein in which the side chains had been removed by heparitinase treatment (“400‐kDa core”) as well as in a 200‐kDa trypsin fragment (“P200”) derived from one end of the core protein. The core protein was sensitive to lyophilization and apparently also to the method of examination, being condensed following Kleinschmidt spreading (length x = 52 nm) and extended following negative staining (length x = 83 nm) or rotary shadowing (length x = 87 nm; 400‐kDa core length x = 80 nm; P200 length x = 44 nm). Two or three glyrosami‐noglycan side chains (length x = 146 + 53 nm) were attached to one end of the core protein. The side chains often appeared tangled or to merge together as one. Thus, the large heparan suifate proteoglycan from basement membrane is an asymmetrical molecule with a core protein containing globular domains and terminally attached side chains. This structure is in keeping with that previously predicted by enzymatic digestions and with the proposed orientation in basement membranes, i.e., the core protein bound in the lamina densa and the heparan suifate side chains in the lamina lucida arranged along the surface of the basement membranes.
New data on the immunocytochemical localization of thyrotropin‐releasing hormone in the rat central nervous system
Authors: Merchenthaler István , Csernus Valér , Csontos Csaba , Petrusz Peter , Mess Béla 
Published: February 2005

AbstractAn antiserum raised against the synthetic tripeptide pyroglutamyl‐histidyl‐proline (free acid) was used to localize thyrotropin‐releasing hormone (TRH) in the rat central nervous system (CNS) by immunocytochemistry. The distribution of TRH‐immunoreactive structures was similar to that reported earlier; i.e., most of the TRH‐containing perikarya were located in the parvicellular part of the hypothalamic paraventricular nucleus, the suprachiasmatic portion of the preoptic nucleus, the dorsomedial nucleus, the lateral basal hypothalamus, and the raphe nuclei. Several new locations for TRH‐immunoreactive neurons were also observed, including the glomerular layer of the olfactory bulb, the anterior olfactory nuclei, the diagonal band of Broca, the septal nuclei, the sexually dimorphic nucleus of the preoptic area, the reticular thalamic nucleus, the lateral reticular nucleus of the medulla oblongata, and the central gray matter of the mesencephalon. Immunoreactive fibers were seen in the median eminence, the organum vasculosum of the lamina terminalis, the lateral septal nucleus, the medial habenula, the dorsal and ventral parabrachial nuclei, the nucleus of the solitary tract, around the motor nuclei of the cranial nerves, the dorsal vagal complex, and in the reticular formation of the brainstem. In the spinal cord, no immunoreactive perikarya were observed. Immunoreactive processes were present in the lateral funiculus of the white matter and in laminae V‐X in the gray matter. Dense terminal‐like structures were seen around spinal motor neurons. The distribution of TRH‐immunoreactive structures in the CNS suggests that TRH functions both as a neuroendocrine regulator in the hypothalamus and as a neurotransmitter or neuromodulator throughout the CNS.
Morphological differences between secretory cells of wet and dry types of human ceruminous glands
Authors: Shugyo Yoshihlko , Sudo Naohiro , Kanai Kazuo , Yamashita Toshio , Kumazawa Tadami , Kanamura Shinsuke 
Published: February 2005

AbstractMorphological differences between secretory cells of the wet and dry types of human ceruminous glands were examined. The heights of secretory cells varied from tall and medium to low in both wet‐and dry‐type glands. The two gland types differed in morphologic features of the tall cells and the cells of medium height. The Golgi apparatus was well developed in the tall cells and fairly well developed in the cells of medium height in the wet‐type gland, whereas it was generally small in the corresponding cells of the dry type. Light granules were abundant in the tall cells and in the cells of medium height in the wet‐type gland, whereas light granules were rare in these cells in the dry‐type gland. Furthermore, the light granules in the wet‐type gland cells were observed in close relation to a well‐developed Golgi apparatus, and sometimes showed a morphologic appearance suggesting exocytosis. Apical protrusions, probably related to apocrine secretion, were generally large and round and bore “microvilli and light granules” or “very few microvilli and no light granules” in the tall cells of the wet‐type gland. However, the protrusions of the tall cells of the dry‐type gland were generally large and slender and possessed no microvilli and no granules. The protrusions were not observed in the cells of medium height or in low cells in either type of gland.The results show that eccrine secretion characterizes the wet‐type gland, but it is not clearly evident in the dry‐type gland. This differences may be related to differences in composition between the wet and dry cerumens.
Fine structure and immunocytochemistry of cells within the endocrine pancreas of larval and adult sea lampreys, Petromyzon marinus L.
Authors: Elliott W. M. , Youson J. H. 
Published: February 2005

AbstractImmunocytochemistry with protein A‐gold and routine electron microscopy were used to identify cell types within the endocrine pancreas of larvae, juvenile adults, and upstream‐migrant adults of the sea lamprey, Petromyzon marinus. The larval pancreatic islets are composed only of insulin‐immunoreactive B‐cells, which are uniform in their fine structure. The cranial and caudal pancreatic tissue in both adult periods contains three cell types: B‐cells, somatostatin‐immunoreactive D‐cells, and a third cell type of unknown content. No glucagon‐immunoreactive cells are present in lampreys, but B‐and D‐cells exist in equal numbers in the pancreatic tissue of adults. The B‐cells of adults have a fine structure similar to those in larvae. D‐cells have secretory granules that are distinctly different from those both in B‐cells and in the third cell type. Although B‐ and D‐cells in lamprey pancreatic tissues have a basic morphological similarity to these cells in other vertebrates, their granules are generally of smaller dimensions. The inclusion of granules within large pleomorphic bodies in many D‐cells indicates that granule turnover is common. Immunocytochemistry will be a useful tool for showing the relationship between the cells in the degenerating bile ducts and those of the developing adult pancreas.
Preservation of the ability of dissociated quail wing bud mesoderm to elicit a position‐related differentiate response
Authors: Stocker Kate M. , Carlson Bruce M. 
Published: February 2005

AbstractPrevious studies showed that grafting wedges of fresh or cultured anterior quail wing mesoderm into posterior slits in chick wing buds resulted in the formation of supernumerary cartilage in a high percentage of cases. When anterior quail mesoderm, which had been dissociated into single cells and pelleted by centrifugation, was grafted into posterior slits of host chick wing buds, supernumerary rods or nodules of cartilage formed in 74.3% of the cases. Few supernumerary skeletal structures formed following control operations in which pelleted dissociated anterior or posterior mesoderm was grafted into homologous locations in host chick wing buds. When pelleted, dissociated anterior mesoderm was cultured in vitro for 1 or 2 days prior to being implanted in posterior locations, the incidence of supernumerary cartilage formation increased to 95.5% and 93.8%, respectively. The incidence of supernumerary cartilage formation following control orthotopic grafts of cultured mesoderm was 11.8% for 1‐day and 31% for 2‐day cultured anterior mesoderm; for 1‐ and 2‐day cultured posterior mesoderm, the incidence of supernumerary cartilage formation was 20% and 41.7%, respectively. Longer‐term culture resulted in a substantial decrease in the percentage of supernumerary cartilage after anterior to posterior grafts and an increase in the incidence of supernumerary cartilage from control grafts. The results demonstrate that quail anterior wing bud mesodermal cells do not need to maintain constant contact with one another in order to retain the ability to form or stimulate the formation of supernumerary cartilage after being grafted into a posterior location in a host wing bud. This ability is retained when the pelleted dissociated mesoderm is cultured in vitro outside the limb field for at least 1 to 2 days.