bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and migration of 3H‐fucose‐labeled glycoproteins in the ciliary epithelium of the eye: Effects of microtubule‐disrupting drugs
Authors: Bennett G. , Haddad A. 
Published: February 2005

Abstract3H‐fucose was injected intravenously or intravitreously into albino rats. After time intervals of 10, 40, and 50 min, 1, 1.5, and 4 hr, 1, 3, and 7 days, and 1, 2, and 4 weeks after injection, the animals were sacrificed by intracardiac perfusion with gluteraldehyde. Samples of the ciliary body were prepared for light and electron microscope radioautography. Light microscope autoradiographs showed that the cells of both the inner and outer layers of ciliary epithelium actively incorporated 3H‐fucose label in a reaction that peaked in intensity at 4 hr after injection, and then progressively declined. Electron microscope radioautographs revealed that, at early time intervals, most of the label was localized to the Golgi apparatus. With time, the plasma membrane of both cell types became increasingly labeled, and accounted for 60–70% of the total silver grains at 4 hr after injection. Adjacent to the basal cell surface of the inner layer cells, the fibers of the zonula became increasingly labeled from 1.5 hr onwards, providing strong evidence that these cells secrete glycoproteins to the zonula. When vinblastine was administered 30 min before 3H‐fucose injection, followed by sacrifice 1.5 hr later, a much larger proportion of label remained localized to the Golgi apparatus than in controls, and the plasma membrane and zonula were much less labeled. These results suggest that, as documented in other cell types, microtubules may play a role in the intracellular transport of membrane and secretory glycoproteins in these cells.
The sexually dimorphic larynx of Xenopus laevis: Development and androgen regulation
Authors: Sassoon David , Kelley Darcy B. 
Published: February 2005

AbstractThe aims of this study were to characterize sexual dimorphism in the larynx of adult Xenopus laevis and to determine how sex differences arise during postmetamorphic development. The larger male larynx is a result of greater cell numbers in both cartilage and muscle. The dilator laryngis muscle of the male larynx has 6–7 times more muscle fibers than that of the female. At metamorphosis, the larynx is sexually monomorphic and feminine in phenotype. The DNA content of the male larynx doubles during the first 6 months following metamorphosis; there is no net DNA increase in the female larynx during this time. Both sexes experience a marked increase in laryngeal DNA content and mass between 6 months and adulthood. The number of muscle fibers in the male larynx increases at an average rate of 150 fibers a day during the first 10 months of postmetamorphic development. There is no net change in fiber numbers in the female larynx from metamorphosis to adulthood. Administration of the antiandrogen Flutamide to metamorphic frogs prevents the net addition of laryngeal muscle fibers in males. Thus, we propose that addition of postmetamorphic laryngeal muscle fibers in males is dependent upon the presence of circulating androgens. Exogenous testosterone administration results in an increase in laryngeal mass, DNA content, and cellular proliferation in juvenile frogs. Using [3H]thymidine injections to probe ongoing, as well as testosterone‐induced, cell proliferation, we conclude that cellular proliferation is regulated differently in males and females during development. Thus androgen‐induced proliferation is one cellular mechanism responsible for the sexual dimorphism observed in adults.
Internal structure of the postcapillary high‐endothelial venules of rodent lymph nodes and Peyer's patches and the transendothelial lymphocyte passage
Authors: Cho Yongock , De Bruyn Peter P. H. 
Published: February 2005

AbstractScanning electron microscopy (SEM) shows that the postcapillary high‐endothelial venules of lymph nodes and Peyer's patches consist of two segments each with a different surface relief: a proximal segment with a cobblestone surface pattern and a distal segment of interlacing cytoplasmic plates. Both segments have deep adluminal crevices in which lymphocytes are lodged. The internal stuctural configuration of this endothelium has been examined by transmission electron microscopy (TEM) of serial sections of lymph nodes and Peyer's patches of mice, rats, and guinea pigs. The serial sections revealed that the endothelial cell bodies and their cytoplasmic extensions were disposed in a direction generally lateral to the luminal surface and intruded into the intercellular spaces of similarly disposed neighboring endothelial cells, resulting in a complex interlacing cellular pattern. Lymphocytes penetrated the endothelial cell body and secondarily followed an intercellular pathway through which they entered the extravascular compartment. At the exposed surfaces of the adluminal venule wall, recirculating lymphocytes were seen in SEM images to enter the endothelium by penetrating the endothelial cell body. The mode of migration of lymphocytes lodged in the endothelial crevices could be determined by SEM and has been examined by TEM of serial sections. At these locations as at the exposed surfaces, lymphocytes also entered the venule by penetrating the endothelial cell body. At both sites this transcellular pathway was followed by lymphocyte entry into the intercellular spaces from which they migrated into the extravascular compartment.
Pluripotent hemopoietic stem cells give rise to osteoclasts
Authors: Schneider Gary B. , Relfson Melanie , Nicolas John 
Published: February 2005

AbstractOsteopetrosis in the ia (incisors absent) rat is the result of reduced bone resorption due to abnormal osteoclasts. The mutant osteoclasts lack a ruffled border—the membrane specialization involved in osteolysis. Studies in the ia mutant have shown that when pluripotent hemopoietic stem cells from normal littermates are transplanted into ia recipients, normal osteoclasts are formed and the skeletal sclerosis is eventually cured. The present study was conducted to provide evidence for the mechanism of the cure. Do the transplanted stem cells provide a helper function, i.e. secrete soluble factor(s) which transform pre‐existing osteoclasts, or do they fuse with each other or pre‐existing osteoclasts, to form functional osteoclasts? Using the procedures described by Goldschneider and co‐workers, and fluorescence‐activated cell sorting (FACS), pluripotent hemopoietic stem cells were isolated from normal rat bone marrow, labeled with saturated FITC, and injected intravenously into irradiated ia rats. After 48 hr, the recipients' long bones were removed and split longitudinally, and the endosteal surface was scraped. The resulting cellular suspension containing osteoclasts was examined by phase contrast and fluorescence microscopy. Fluorescing mononuclear cells of donor origin that had homed to the bone marrow demonstrated moderate cytoplasmic fluorescence. Approximately 30% of the osteoclasts observed demonstrated light cytoplasmic fluorescence. When cellular pools incapable of curing osteopetrosis (thymocytes) were labeled and injected into ia recipients, no labeled osteoclasts were observed. These studies indicated that pluripotent hemopoietic stem cells, when transplanted into ia hosts, fuse with each other and differentiate into osteoclasts or fuse with pre‐existing osteoclasts.
Induction of a specific (LM) protein in the submandibular gland of the rat by repeated amputation of the lower incisor teeth
Authors: Yagil Chana , Barka Tibor 
Published: February 2005

AbstractChronic administration of the β‐adrenergic agonist isoproterenol (IPR) leads to marked hyperplastic/hypertrophic enlargements of the parotid and submandibular glands in rats and mice with concomitant changes in the composition of both the glands and the saliva. Conspicuous among the alterations of the submandibular saliva is the appearance of a 13,000 Mr protein, termed LM (large mobile) protein. Repeated amputation of the lower incisor teeth also causes enlargements of the major salivary glands in rats. In this study, we have compared the enlargements of submandibular glands of rats produced by IPR administration or teeth amputation with respect to the relative levels of the LM protein in gland extracts and saliva. Adminstration of IPR‐HCI (40 mg/kg) twice daily for 5 days or amputation of the lower incisor teeth 3 times a week for 3 weeks resulted in a 2.2‐fold increase in the weight of the submandibular gland. Amputation for one week led to a 1.4‐fold increase in gland weight. Double immunodiffusion in agar antibodies against the purified LM protein gave a single preciptin line with gland extracts and saliva of IPR‐treated and teeth‐amputated rats, indicating immunological identity of the reacting antigens. No precipitin lines were seen with gland extracts or saliva of untreated rats. Immunoblots of pooled saliva obtained from IPR‐treated or teeth‐amputated rats revealed a single protein band of the same electrophoretic mobility in SDS‐polyacrylamide gels when stained using anti‐LM antibodies. The relative concentrations of LM protein in gland extracts and saliva were measured by a solid‐phase enzyme‐linked immunoabsorption assay using antibodies aginast the purified LM protein. In gland extracts of untreated rats, LM protein was not measurable. Both amputation and adminstration of IPR resulted in marked increase in the relative concentrations of the LM protein. However, the relative concentration of LM protein in extracts of glands of teeth‐amputated rats was only about one‐fifth of that found in extracts of glands of IPR ‐treated animals irrespective of the duration of the amputation. LM protein was localized immunocytochemically in the cytoplasm of acinar cells and in the striated duct cells. These data indicate that both amputation of incisor teeth and β‐agonist administration lead to the induction of the same protein in the submandibular glands of rats, although the mechanism by which these two types of interventions cause enlargement of the gland may not be identical.
Chondroid bone on the upper pharyngeal jaws and neurocranial base in the adult fish Astatotilapia elegans
Authors: Huysseune A. , Verraes W. 
Published: February 2005

AbstractSerial cross sections of several adult specimens of the cichlid Astatotilapia elegans were used to investigate the fate and structure of the chondroid bone on the articulation between upper pharyngeal jaws and neurocranial base. The tissue persists in the adult on the three elements on which it previously developed, i.e., infrapharyngobranchial III‐IV, parasphenoid, and basioccipital bones. It consists of haphazardly arranged, large vesicular cells without a canalicular system, embedded in a matrix histologically indistinguishable from bone matrix. Except for a narrow zone at the distal side, it is mineralized throughout. As in younger stages, the fibrous covering of the chondroid bone forms the articular tissue proper on each of the three elements. Acellular bone, found at the basal margin of the chondroid bone, it is argued, does not result from endochondral replacement of the latter but rather from dermal ossification projecting from the marrow cavity. Although lacunae may be filled in this way with bone, true obliteration of cells does not occur, so that there is no metaplasia from chondroid bone to bone. The part played by the chondroid bone in the outgrowth of the joint apophyses is discussed.
Changes in pancreatic acinar cell nuclear number and DNA content during aging in the rat
Authors: Oates Phillip S. , Morgan Reginald G. H. 
Published: February 2005

AbstractPancreatic acinar cells from rats 5 to 658 days (94 weeks) of age were isolated by enzymatic dissociation and stained with the DNA specific fluorochrome Hoechst 33258. The nuclear DNA content and the incidence of binucleation were estimated in these cells. Total pancreatic weight, RNA, protein and DNA, and the incorporation of 3H‐thymidine into pancreatic acinar cell DNA were also estimated in similar animals as measures of pancreatic growth. From 5 to 17 days after birth, 95% of the cells were mononucleate diploid and 5% were binucleate diploid; but during the period of rapid pancreatic growth over the following 39 days, acinar cells became increasingly binucleate. By 56 days after birth, 64% of cells were binucleate with a diploid DNA content per nucleus; and the incidence of binucleation then remained constant. At 28 days of age, 4% of mononucleate cells were tetraploid, increasing to 6% at 658 days of age. At this time 3% of binucleate cells contained dual tetraploid nuclei. There is thus a rapid development towards diploid binucleate acinar cells in the growing, postnatal pancreas; and in the adult pancreas a small proportion of these cells develop tetraploid nuclei.
Histochemical evaluation of glycoconjugates in the male reproductive tract with lectin‐horseradish peroxidase conjugates: I. Staining of principal cells and spermatozoa in the mouse
Authors: Burkett Barbara N. , Schulte Bradley A. , Spicer Samuel S. 
Published: February 2005

AbstractSeveral glycoconjugates are thought to bind spermatozoa as they pass through reproductive ducts. Paraffin sections of testis, ductuli efferentes, epididymis, and vas deferens of male mice were stained with ten different lectin‐horseradish peroxidase conjugates to localize possible sites of synthesis and secretion of such glycoconjugates, based on the carbohydrate moieties in their constituent oligosaccharide side chains. Principal (columnar) cells lining the efferent ducts, germinal epithelium, and developing and maturing spermatozoa were examined with light microscopy. Staining of the Golgi and apical zones of cells was interpreted as evidence for synthesis and secretion of glycoconjugates. Principal cells synthesized and secreted glycoconjugates with sugar moieties as follows: sialic acid, all regions of the efferent ducts examined; the terminal disaccharide D‐galactose‐ (β1 → 3) ‐N‐acetyl‐D‐galactosamine, all regions of ducts except epididymis I; terminal α‐D‐galactosamine, some cells in epididymis III‐V; N‐acetyl‐D‐galactosamine, ductuli efferentes, epididymis I, II, and some cells in epididymis III‐V; α‐L‐fucose, ductuli efferentes, vas deferens, and all regions of the epididymis except IV; N‐glycosidic side chains, ductuli efferentes, vas deferens, and epididymis I, IV, and V. All of these sugar residues as well as N‐acetyl‐D‐glucosamine were associated with the acrosomes and tails of spermatozoa throughout the ducts except for α‐N‐acetyl‐D‐galactosamine in epididymis I, and all occurred during one or more stages of spermiogenesis. The synthesis and secretion of glycoconjugates that bind to spermatozoa appear to involve more regions of the primary reproductive structures than was believed previously.
Histochemical evaluation of glycoconjugates in the male reproductive tract with lectin‐horseradish peroxidase conjugates: II. Staining of ciliated cells, basal cells, flask cells, and clear cells in the mouse
Authors: Burkett Barbara N. , Schulte Bradley A. , Spicer Samuel S. 
Published: February 2005

AbstractEfferent reproductive ducts of male mice, including ductuli efferentes, epididymis, and vas deferens, were fixed and embedded in paraffin, and sections were stained with a battery of lectin‐horseradish peroxidase conjugates to localize specific sugars or sugar sequences in glycoconjugates. Cilia and the apical surfaces of ciliated cells in the ductuli efferentes stained intensely with lectin specific for sialic acid and terminal α‐N‐acetyl‐D‐galactosamine. Flask cells and clear cells in the epididymis reacted positively and similarly with most lectins used, providing evidence that these cell types are related. In contrast, disparities in lectin staining suggest that flask cells and clear cells are a cell type distinct from principal cells. Basal cells were not present in the ductuli efferentes but formed a continuous layer in the epididymis and vas deferens. Basal cells contained oligosaccharides terminated by sialic acid and α‐D‐galactose and varying amounts of terminal β‐D‐galactose and α‐N‐acetyl‐D‐galactosamine. Basal cells also stained variably with lectins specific for the core region of complex type N‐glycosidic side chains. The basal cells varied structurally, having long spinous apical processes approaching or reaching the lumen in region I of the epididymis and being low cuboidal or squamoid and lacking apical processes in epididymal regions II–V and in the vas deferens. The contiguous nature of the basal cells and the presence of glycoconjugates bearing terminal α‐galactosyl residues in all basal cells suggest a possible role for these cells in a regulatory influence on transepithelial movement of fluid and/or ions in the epididymis and vas deferens.
Ultrastructural differentiation of stromal and vascular components in early macaque placental villi
Authors: King Barry F. 
Published: February 2005

AbstractIn this study, closely staged placental villi from rhesus monkeys between 19 and 60 days of gestation were used to examine (1) the origin of endothelial cells and the mechanism of angiogenesis in villi; (2) the origin of placental macrophages (Hofbauer cells), and (3) the origin of the reticular cells that compartmentalize the stroma. The results did not support the concept that early stromal cells in the villi were derived by in situ delamination from cytotrophoblast. The extraembryonic mesodermal (mesenchymal) cells at the earliest of ages examined contained considerable granular ER. These cells organized into groups and formed primitive intercellular junctions, thus giving rise to the early angioblastic masses. The angioblastic masses were cellular, not syncytial; and lumen formation was not the result of intracellular vacuolization, but rather was the result of the acquisition of junctionally defined spaces. The earliest capillaries lacked intravascular blood cells and a basal lamina. Later, blood cells were evident in the lumina. At about 45–50 days of gestation, fetal capillaries began to indent the basal surface of the trophoblast. The basal lamina of the fetal capillaries still had not developed by 60 days of gestation. Between 35 and 40 days of gestation, significant morphological changes took place in the villous stroma. Evidence was obtained that the mesenchymal cells differentiated into the reticular cells that subdivided the stroma into fibrilrich and fibril‐free compartments. At the same time, Hofbauer cells were observed for the first time; they occupied the fibril‐free regions of the stroma. We did not observe any clear indications of intermediate stages of differentiation between other stromal cell types and Hofbauer cells. It is suggested that placental macrophages may have an origin independent of other stromal types; one possibility is that they are derived from blood monocytes as in other tissues. It is further suggested that the activities of the macrophages and reticular cells may be important in remodeling the extracellular matrix and may be related to the process of branching morphogenesis in the villi.
Thalamic arterial pattern: An endocast and scanning electron microscopic study in normotensive male rats
Authors: Rieke Garl K. 
Published: February 2005

AbstractRat cerebral vasculature serves as a model for study of the pathophysiology of stroke in humans. Human thalamic anteries show a high incidence of stroke. The objective is to describe the thalamic arterial vascular pattern in normotensive male rats as the initial step for quantitative histochemical studies of enzyme activities in the walls of these vessels. Intracardiac injections of methyl methacrylate monomer provide detailed vascular endocasts. The thalamic vascular bed defined by in situ dissection, serial reconstruction, and light and scanning electron microscopy of endocasts contained four groups of vessels: (1) ventral medial thalamic arteries, (2) thalamic branches from the posterior cerebral artery, and (3) ventral lateral and (4) ventral anterior thalamic arteries. Thalamic vessels are muscular arterioles that, after three to four bipinnate branches, feed into a continuous capillary bed (no loops). The parent vessels and their subsequent branches have been evaluated in terms of their mean internal diameters, mean interbranch intervals, and branch angles. The arterial patterns to rat and human thalami are very similar, with the exception of the anterior choroidal artery which is missing in the rat. The branches supplying the thalamus in both the rat and human are closely associated with the circle of Willis; however, the constituent parts of the circle in rat vary from the pattern in human brain. The rat thalamic arteries show morphological features similar to those seen in the stroke‐prone ganglionic arteries in the human basal ganglia.
Rathke's pouch grafts in adult brain sites
Authors: Schechter Joel , Gash Don , Ahmad Nazir 
Published: February 2005

AbstractDonor tissue containing Rathke's pouch (RP) with its associated mesenchyme and neural lobe was isolated from 15‐day fetal rats and stereotaxically transplanted either to hypothalamic hypophysiotropic sites or to cerebral cortex of adult females for 30 days. Hosts either were intact or had been hypophysectomized 2–4 weeks prior to transplantation of Rathke's pouch. Grafts in the hypothalamus of either intact or hypophysectomized hosts were pleomorphic and large, often as wide as 1–2 mm, and occasionally larger. Grafts in the cortex of either intact or hypophysectomized hosts were nodular and occasionally projected upward in association with the meninges (cortex/meninges grafts).Certain features were characteristic of the grafts in all experimental groups, i.e., development of histotypic pars distalis with cell cords and fenestrated capillaries. In all experimental groups gonadotrophs and somatotrophs, when present, were localized at the graft margin adjacent to the connective‐tissue interface; mammotrophs, when present, were distributed throughout the graft. Features specific to each experimental group also were apparent. Grafts in the hypothalamus of both intact and hypophysectomized hosts typically were encapsulated by a labyrinthine meshwork of cell processes, whereas cortex/meninges grafts directly abutted dense connective tissue or neural tissue. In hypothalamic grafts in intact hosts, moderately differentiated mammotrophs, gonadotrophs, and somatotrophs could be identified by their cytological features and immunopositivity for prolactin, luteinizing hormone, and growth hormone, respectively. In hypothalamic grafts in hypophysectomized hosts, mammotrophs were absent, and gonadotrophs and somatotrophs were poorly granulated and not abundant. Grafts in the cortex of intact hosts contained numerous, well‐differentiated mammotrophs, gonadotrophs, and somatotrophs. Many of the mammotrophs in these grafts were hypertrophied, and profiles of exocytosis were common. In grafts in the cortex of hypophysectomized hosts, mammotrophs were either absent or very few, whereas gonadotrophs and somatotrophs were numerous. Gonadotrophs in these grafts were dramatically hypertrophied, although exocytosis was rare.The results indicate that development of histotypic pars distalis may occur in hypophysiotropic and nonhypophysiotropic brain sites and that the hormonal state of the host as well as implantation site modulate cytodifferentiation of specific pars distalis cell types.