bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of the bovine epididymis
Authors: Goyal Hari Om 
Published: February 2005

AbstractThe epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II–V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 μm in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 μm in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well‐developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II–VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogenous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.
Development of neuroepithelial bodies in intact and cultured lungs of fetal rats
Authors: Carabba Victor Hugo , Sorokin Sergei Pitirimovitch , Hoyt Richard Francis 
Published: February 2005

AbstractIntact, 14‐ to 21‐day fetal rat lung pairs, neonatal lungs, and cultured 15‐ and 16‐day lung explants were examined in 2‐μm‐thick glycol methacrylate sections stained by PAS‐lead hematoxylin. Selected stages were also studied in histochemical preparations for aliesterase and formaldehyde‐induced monoamine fluorescence, as well as by scanning and transmission electron microscopy. Neuroepithelial bodies (NEBs) first appear in pseudoglandular lungs at 15 days in vivo as pyramidal groups of basal, diffusely lead‐hematoxylin‐positive cells in glycogen‐depleted epithelium of main and lobar bronchi. By day 16, primitive NEBs occur within three to four generations of the terminal buds, and older, proximal bodies are larger and more distinctive than at 15 days. Aliesterase activity is first detected in basally located, developing NEBs on day 16. During the canalicular and alveolar sac periods, NEBs appear and mature on a proximal‐to‐distal gradient along the airway, as they do in developing rabbit and human lungs. As earlier‐formed airways elongate, additional NEBs appear and supplement the population already present. By days 20–21, NEBs occur at all airway levels down to the bronchiolo‐alveolar junctions, and many of the cells have discrete PAS‐ and lead‐hematoxylin‐positive, infranuclear granules. Near term some NEBs exhibit serotonin fluorescence after incubation in 5‐hydroxytryptophan and have abundant, ca. 100‐nm, electron‐dense granules. These are concentrated toward the cell base like the stained granules visualized by light microscopy. Similar results were obtained from lungs placed in organ culture. From 2 days in culture to a time equivalent to term, NEB formation parallels that in vivo, indicating that developmental requirements are met in in vitro. Taken altogether, morphologic and cytochemical evidence suggests that NEBs of rats are functional in late fetal life and that their development is relatively independent of extrapulmonary influences and of the intraepithelial ingrowth of sensory nerve endings.
Distribution of dipeptidyl peptidase II (Dpp II) in rat spinal cord
Authors: Gorenstein Charles , Swett John E. 
Published: February 2005

AbstractThe histochemical localization of dipeptidyl peptidase II (Dpp II; E.C. 3.4.14.2) activity was demonstrated at the light microscope level in the rat spinal cord. Prominent staining was observed in motoneurons of the ventral horn and in medium to large neurons in the deep laminae of the dorsal horn, the intermediate gray, and in lamina X surrounding the spinal canal. Within neurons, Dpp II was localized largely in cell perikarya and large primary dendrites with no staining observed in cell nuclei. Neurons in the superficial dorsal horn lack Dpp II enzyme activity. Nonneuronal elements which also stained prominently were pericytes associated with blood vessels and ependymal cells lining the lumen of the spinal canal. A few oligodendrocytes and astrocytes were also stained, but they represented a minor component of the total amount of Dpp II activity. Following ventral root injury, Dpp‐II‐containing motoneurons degenerate; some glial cells in the region of degenerating neurons become Dpp II positive. The localized distribution of Dpp II in spinal cord neurons suggests that this proteolytic enzyme may play a role in the metabolism of an unidentified neuropeptide.
Reproductive biology of the female leaf–nosed bat, Macrotus californicus, in southwestern united states: I. A morphometric analysis of the annual ovarian cycle
Authors: Crichton Elizabeth G. , Krutzsch Philip H. 
Published: February 2005

AbstractIn Macrotus californicus (Phyllostomatidae), normal embryogenesis (March–June) is preceded by a period of delayed development (October – March) characterized by implantation and slow growth of the embryo to the primitive streak stage. The events of the annual reproductive cycle can be correlated with ovarian dynamics. Waves of follicular growth appear to be initiated in January and June. Increased multilaminar follicles resulting from the second wave of recruitment appear from August to October. Vesiculation of these follicles is seen in both ovaries from July to January; however, the single Graafian follicle forms only in the right ovary just prior to ovulation in late October‐early November. Left ovarian ovulation can be induced by right ovariectomy. High atresia from July to December may retard embryogenesis by failing to provide an optimal hormone milieu for the conceptus. In addition, luteal cells are small during the initial months of embryonic development. The first wave of follicular growth results in the appearance of an increased percentage of growing follicles in April; resultant enhanced estrogen levels may influence the resumption of normal development, an event which also coincides with luteal cell hypertrophy. It would appear possible, therefore, that delayed development in Macrotus is an expression of luteal cell insufficiency and uterine nutritional incompetence resulting from depressed steroid levels. Termination of delay may be brought about by the action of increased levels of estrogen and/or progesterone on the endometrium, perhaps by influencing the activity of mast cells whose products are known in some species to enhance vascularity which in turn could account for added substances essential to normal fetal growth.
Detection of anionic sites on the cytoplasmic surface of the guinea pig acrosomal membrane
Authors: Enders George C. , Friend Daniel S. 
Published: February 2005

AbstractThe sperm acrosome reaction is an example of exocytosis, accomplished through the fusion of the acrosomal and plasma membranes. As in other examples of exocytosis, the acrosome reaction is initiated by an influx of Ca++, which may promote fusion by binding to anionic sites on adjacent bilayers. In this study we used ruthenium red (RR) and cationic ferritin (CF) to detect anionic sites on the surfaces of acrosomal and plasma membranes of guinea pig spermatozoa. These probes indicate a dense concentration of anionic sites on the cytoplasmic surface of the acrosomal membrane. Higher concentrations of salt (NaCl) were required to inhibit cationic probe labeling of the cytoplasmic surface of the acrosomal membrane compared to the concentration needed to inhibit the plasma membrane binding. The added NaCl also increased the separation of the plasma from the acrosomal membrane. Low‐pH buffers stop cationic probe labeling of both membranes. Sections tangential to the acrosomal membrane revealed that the cation probes bound in a linear pattern, similar to the periodicity and distribution of intramembraneous particles observed in freeze‐fracture replicas. Following fusion of the plasma and acrosomal membrane during the acrosome reaction, we could no longer detect a dense concentration of anionic sites on the cytoplasmic surface of the fused vesicles. The results indicate that the dense concentrations of anionic sites are either masked or lost following fusion with the overlying plasma membrane.
A functional and morphological study of cells adjacent to ectopic bone implants in rats
Authors: Walters Linda M. , Schneider Gary B. 
Published: February 2005

AbstractSubcutaneous implantation of bone chips into normal and osteopetrotic (ia) rats results in the formation of multinucleate giant cells (MNGCs) adjacent to the bone surface. In this study the resorptive and morphological characteristics of the cells surrounding these implants were assessed to determine if the bone‐resorbing defects seen in ia animals would be mimicked, thus giving validity to the use of this system as a model for the study of osteoclastic lineage and function. Direct measurement of in vivo bone resorption was achieved through the use of 45Ca‐labelled bone‐chip pairs that were primarily osteoid‐exposed and freeze‐thawed (FT), primarily mineral‐exposed and bleached (B), or primarily mineral‐exposed and collagenase‐treated (CT). Comparison of the 45Ca content of implanted chips to that of controls indicated the total 45Ca release during a two‐week implantation period. There was no significant difference in the amount of label released between normal and ia animals. Both normal and ia rats showed 23% greater total 45Ca release from mineral‐ versus osteoid‐exposed matrix. Cellular events occurring on the bony substrate were evaluated by light and electron microscopy. At 3 days, bone chips were surrounded primarily by mononuclear cells. By 14 days, MNGCs were present at the bone surface in both ia and normal animals. In mineral‐exposed implants, 40–50% of the bone surface was covered by MNGCs as compared to 20% of the osteoid‐exposed surface. These MNGCs possessed occasional clear zones, but did not exhibit ruffled borders; therefore, they could not be classified as osteoclasts. Thus, the defects seen in ia mutants were not reproduced in this implant system. The 45Ca release that occurred was probably due to the action of mononuclear phagocytes and macrophage polykaryons rather than to true osteoclastic bone resorption.
Mucosal nerves and smooth muscle relationships with gastric glands of the opossum: An ultrastructural and three‐dimensional reconstruction study
Authors: Seelig L. L. , Schlusselberg D. S. , Smith W. K. , Woodward D. J. 
Published: February 2005

AbstractThe precise anatomical relation by which autonomic nerve endings contact gastric epithelial cells to enhance the rate of gastric secretions is not fully understood. The aim of the present study was to clarify this issue by using the technique of serial section reconstruction of areas of the gastric mucosa. The work also explored the possibility of a functional role for a system of smooth muscle strands in the gastric mucosa that emanate from the muscularis mucosa, run in the lamina propria, and are associated in a unique manner with the gastric glands. Electron microscopic serial sections of the gastric mucosa were performed to visualize the entire limiting membrane of gastric epithelial cells to determine any nerve associations (especially varicose endings) with these cells. Evaluation of serial sections of five separate parietal cells showed that their basal membrane did not come in close contact (nearest distance 500 nm) with any nerve axon or varicosity. Moreover, the axons passing in the area of these cells ultimately showed varicose endings associated with smooth muscle cells in the adjacent connective tissue (often separated by only 20 nm), with mast cells or with vascular elements. Additionally, the lateral membrane of these five parietal cells did not contact any endocrine cell in the epithelium, although other parietal cells in the area were adjacent to endocrine cells. Chief cells in the immediate area also did not form any close associations with nerve varicosities. Random analysis of 5,000 additional epithelial cells in these sections showed no close associations to nerve elements with significant accumulations of neurosecretory vesicles (varicosities). Because of the observed existence of innervation to the smooth muscle strands in the area of the gastric glands, serial 1‐μm epoxy sections of the gastric mucosa were prepared, and profiles of smooth muscle and gastric glands were entered into a computer‐assisted reconstruction system. Three‐dimensional reconstruction techniques were employed to reveal the existence of a unique association between the mucosal smooth muscle strands and the gastric glands. The muscle strands arose from the muscularis mucosa at regular intervals and became branched to form an intricate wrap around a series of gastric glands that empty into one gastric pit. Branching of the muscle strands initially occurred at the point where they approached the base of the glands and then emanated into the connective tissue around the glands in a crossing pattern, ending at the base of the gastric pit. Although muscarinic agents have been shown to directly stimulate parietal cells to secrete acid, these findings have led us to postulate that autonomic nerve stimulation may also aid gastric secretion both by stimulation of mast cells and by glandular excretion mediated via mucosal muscular contractions.
The effects of chlorcyclizine‐induced glycosaminoglycan alterations on palatal mesenchyme‐basal lamina relationships in the mouse
Authors: Brinkley Linda L. , Morris‐Wiman Joyce 
Published: February 2005

AbstractThe relationships of mesenchymal cells to the basal lamina underlying regions of the palatal‐shelf epithelium that are known to increase in cell density during shelf reorientation are quantitatively different from those of cells underlying neighboring regions that do not increase in cell density. Chlorcyclizine‐induced alterations of the extracellular matrix were used to investigate the possible contribution of extracellular matrix to these differences. Chlorcyclizine causes hyaluronate and the chondroitin sulfates to be degraded into pieces with smaller molecular weights and lower charge densities, with little or no effect on their synthesis, and also results in cleft palate. Pregnant CD‐1 mice were gavaged with chlorcylizine on days 10.5, 11.5, and 12.5 of gestation, and the fetuses were harvested on day 13.5. Some palatal shelves were excised immediately and fixed for electron microscopy; other heads were partially dissected and incubated for 4 hr prior to fixation. In normal heads differences in mesenchymal cell configurations are detectable after 4 hr in vitro. Electron micrographs were taken of the epithelial‐mesenchymal interface in nasal and oral regions that increased in epithelial cell density and in nasal and oral regions which did not. Several variables of mesenchymal cell configuration were measured in a 500‐nm‐wide zone delimited on photographic prints. Chlorcyclizine‐induced glycosaminoglycan alterations resulted in quantifiable, region‐specific differences in mesenchymal cell relationships to the basal lamina and in the ultrastructural appearance of the zone immediately subjacent to the basal lamina. These results suggest that the epithelial‐mesenchymal interface and sublaminar zone of the nasal and oral regions as well as their active and inactive segments may be constitutively different.
Passage of microspheres through vessels of normal and split hydronephrotic rat kidneys
Authors: Sossenheimer Michael , Fleming John T. , Steinhausen Michael 
Published: February 2005

AbstractMicrospheres (15 μm) were injected intracardially in rats. By means of in vivo microscopy of the split hydronephrotic kidney microcirculation, the passage of microspheres through renal blood vessels was analyzed. Additionally, three sets of experiments were conducted, one consisting of rats with nonnal kidneys, one of rats 1th hydronephrotic kidneys, and one of rats with hydronephrotic kidneys under vasodilation. In vivo microscopic as well as histological studies show that the passage of 15‐μm microspheres is dependent on the postinjection interval Microspheres are capable of locally dilating preglomerular vessels and moving towards the glomeruli. Therefore, estimates of preglomerular vessel diameters with microsphere experiments ought to be controlled by intravital microscopy.
Development of the vasculature of the pectoral fin in the Australian lungfish, Neoceratodus forsteri
Authors: Saito Hiroaki 
Published: February 2005

AbstractThe development of the vasculature of the pectoral fin in the Australian lungfish, Neoceratodus forsteri, was studied by the dye‐injection method. Only a single primitive subclavian artery appears from the dorsal aorta for the fin anlage, and it passes laterally through the postaxial region of the structure. The venous channel draining into the posterior cardinal vein is located in the preaxial region medially. As development proceeds, the arteriovenous arrangement in the pectoral fin anlage changes as follows: (1) one artery and one venous plexus, (2) two arteries and one vein, (3) three arteries and one vein, (4) four arteries and one vein, (5) three arteries and two veins, and (6) two arteries (radial and ulnar) and three veins (radial, ulnar, and ulnar marginal).The fin anlage through embryonic first rotation has gradually changed its postaxial margin to face dorsally and its preaxial margin to face ventrally. The second rotation causes the original preaxial margin to become dorsal and the original postaxial margin to become ventral. As a result, the radial and ulnar arteries are observed in the dorsal and ventral regions, respectively, in the medial side of the fin instead of in the lateral side as seen in the previous stage.
Skeletal biology in the toothless (osteopetrotic) rat
Authors: Seifert Mark F. , Popoff Steven N. , Marks Sandy C. 
Published: February 2005

AbstractThe toothless (tl) rat is a nonlethal osteopetrotic mutation characterized by the presence of few osteoclasts and the failure to be cured by bone‐marrow transplantation. We examined the skeletal biology of tl rats and normal littermates up to 6 weeks after birth. Osteoclasts in tl rats were small, reduced 25‐fold in number, and had greatly reduced concentrations of acid hydrolases. Bone shape internally and externally reflected reduced bone resorption, and tl rats were hypophosphatemic and mildly hypocalcemic at 2 weeks. These data indicate that the basic defect in tl rats is one of differentiation of osteoclasts and, coupled with the observation that normal bone‐marrow cells cannot develop into osteoclasts in the tl skeleton, suggest that the defect lies in the skeletal microenvironment.
Normal stages of cardiac organogenesis in the mouse: I. Development of the external shape of the heart
Authors: Vuillemin Mauricette , Pexieder Tomas 
Published: February 2005

AbstractNormal development of the mouse embryonic heart was studied at the organ level using microdissection and scanning electron microscopy (SEM). Altogether 225 embryos, sampled at 8‐hour intervals between 11ed (ed = embryonic day; day of vaginal plug = led) and 15ed were collected. Their hearts were fixed by high flow‐low pressure perfusion, micro‐dissected, and observed in SEM. Standardized frontal, right profile, and left profile SEM micrographs were obtained and analyzed.The main purpose of this study was to create a series of normal stages of mouse cardiac development as a reference for ongoing studies in experimental cardiac teratology (e.g., in fetal mouse trisomies). Comparisons with chick, human, and dog embryonic hearts, prepared using the same technique, show that the mouse embryonic heart is characterized by a relatively deep interventricular sulcus. The absence of a conoventricular sulcus in the mouse results in poor definition of the boundary between the conus and the right ventricle. The external separation of the aorta and the pulmonary artery is evident from 13ed onward. The respective positions of the great arteries (aorta dextroposterior, pulmonary artery sinistroanterior) does not change until the end of cardiac organogenesis (15ed in the mouse).
Hemopoiesis in the human yolk sac
Authors: Takashina Toshimitsu 
Published: February 2005

AbstractThe endodermal layer of the human yolk sac was examined three‐dimensionally with light microscopy on serial sections using scanning electron microscopy and transmission electron microscopy to find the origin of hemo poiesis in the yolk sac. Cell‐labelling techniques were also employed using the monoclonal anti‐transferrin receptor antibody. Orifices of the endodermal and intracellular tubules facing the yolk‐sac cavity were demonstrated on the endodermal surface. Various‐sized blood cells in various stages of differentiation and maturation were distributed in the yolk‐sac cavity and tubules and were observed also at the orifices of the tubules. The morphological and the immunological findings suggest that blood cells with large nuclei in the endodermal layer are the most immature. The present results suggest that blood cells originate from the endodermal layer and are carried to the embryo through the yolk sac cavity and the vitel‐line duct. It is probable that the endodermal and intracellular systems of tubules have an important role in the transport of blood cells, including stem cells.
Bidirectional closure of the rostral neuropore in the human embryo
Authors: O'Rahilly Ronan , Müller Fabiola 
Published: February 2005

AbstractThe length of each neuropore was measured in 23 human embryos of stages 10–12 (about 22–26 days), and the closure of the lips of the rostral neuropore was studied in 24 embryos of stage 11 (about 24 days), with particular reference to the terminal lip. Graphic reconstructions were prepared from two particularly suitable examples, and mitotic figures were plotted for one of these. The lengths of the rostral and caudal neuropores are basically similar, but the rostral opening closes 1 day earlier and more abruptly (within a few hours) than the caudal (which takes a day). Closure of the rostral neuropore in the human embryo is bidirectional, proceeding simultaneously from (1) midbrain and diencephalon 2 and (2) the telencephalic region adjacent to the chiasmatic plate. Species differences are emphasized. Closure at the terminal lip of the neuropore is by fusion of right and left neural folds, as occurs elsewhere during primary neurulation. The rostral end of the neural plate in the median plane is, in the human embryo, at the rostral limit of the chiasmatic plate. Histological differences, however, exist between closure at the terminal lip and that at the dorsal lip: the surface epithelium plays a more significant role at the terminal lip, and the seam is more visible and presumably stronger. In future anencephaly it has been found that fusion at the terminal lip may occur, although that at the dorsal lip is deficient.