bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transverse sections of the elbow region in man, made into transparencies and embedded in plastic in a self‐study module
Authors: Lataster L. M. A. , Rensema J. W. , van Mameren H. , Drukker J. 
Published: February 2005

AbstractThis paper describes a valuable tool for medical teaching. It is a detailed description of a method to present transparent sections embedded in plastic, placed in a self‐instruction module by means of a vertical storage system. It includes the use of three‐dimensional graphic reconstructions. Other applications are also indicated.
Mesonephric excretory function related to its influence on differentiation of fetal gonads
Authors: Grinsted Jørgen , Aagesen Lotte 
Published: February 2005

AbstractThe mammalian intermediate fetal kidney, the mesonephros, is known in different species to excrete body waste products during a limited period of fetal life. Recently, the mesonephros and its derivatives have been shown to influence gonadal functions in several ways. Thus, the mesonephric cells are responsible for regulating the onset of meiosis in different mammals by the secretion of two substances, a meiosis‐inducing substance (MIS) and a meiosis‐preventing substance (MPS).In this paper, the relation between mesonephric kidney function and its influence on the gonads is reviewed through literature studies. It seems that cessation of mesonephric excretion precedes onset of meiosis in the ovary in different species.It is suggested that the mesonephric renal function interferes with synthesis and/or secretion of MIS or that the excreted products may interfere with the responsiveness to MIS of the germ cells.
Receptor‐mediated endocytosis of glucagon in isolated mouse hepatocytes
Authors: Watanabe Jun , Kanamura Shinsuke , Asada‐Kubota Mari , Kanai Kazuo , Oka Motoko 
Published: February 2005

AbstractThe binding of glucagon to the cell surface and the pathway of intracellular transport of the hormone in isolated mouse hepatocytes were studied by autoradiography, colloidal gold‐labeled glucagon (Au‐glucagon), and biochemical methods. In cells incubated with 1251‐glucagon at 4°C, the label was mainly localized to the plasma membrane even after 60 min of incubation. At 20°C, the labeled ligand was internalized by the cells and the amount of internalized ligand increased with time of incubation. At 37°C, the ligand was rapidly internalized and found to be associated with coated or uncoated vesicles. Au‐glucagon experiments revealed clearly the process of internalization of glucagon. Au‐glucagon bound to the plasma membrane was transported to coated regions and then internalized into vesicles via coated pits. Biochemical results supported these findings from autoradiography and Au‐glucagon experiments. Thus, glucagon is internalized by hepatocytes via receptor‐mediated endocytosis.
Effects of chronic ACTH stimulation on the morphology of the rat adrenal cortex
Authors: Pudney J. , Price G. M. , Whitehouse B. J. , Vinson G. P. 
Published: February 2005

AbstractThe effects of chronic ACTH treatment (Depot Synacthen, 100 μg/day) on the morphology of the rat adrenal were studied in animals treated for 1 to 18 days. The gross weight of the adrenal increased up to tenfold, but although mitotic figures were seen after 3 days in the glomerulosa region, most of this is attributable to a vast increase in blood content. After 3 days of treatment the sinusoids in the reticularis became extremely dilated, and red blood cells penetrated the endothelial wall to become tightly packed around the cortical cells. This led to the gross distortion of the organization of the cortical tissue and after 7 days the cells in the reticularis region were isolated from each other by the continual infiltration of red blood cells. These changes gradually progressed outward so that other regions of the cortex became similarly affected. Eventually the cord‐like arrangement of the fasciculata was disrupted. After 18 days of treatment, most of the cortex was involved and only a very thin layer of cells lying beneath the adrenal capsule was seemingly unaffected. Another major effect of corticotrophin treatment was the gradual loss of cellular differentiation, particularly of glomerulosa cells. Although the glomerulosa appeared normal after 1 day of treatment, cells of the fasciculata abut directly on the connective tissue capsule following 3 days of ACTH administration. Eventually glomerulosa cells disappeared almost completely, although there was no sign of cellular necrosis. It is likely that glomerulosa cells are transformed into fasciculata‐type cells under ACTH treatment. This interpretation is consistent with functional changes that occur at the same time, including the loss of aldosterone synthetic capacity.
In vivo experimentation on rat incisor enamel organs through a surgical window
Authors: McKee M. D. , Warshawsky H. 
Published: February 2005

AbstractExperimental agents administered systemically are costly and often toxic to animals. An in vivo technique has been developed whereby a surgical window in the alveolar bone allows selected areas of the rat incisor enamel organ and underlying enamel to be exposed to various drugs, radiolabeled molecules, and molecular weight markers. Sherman rats weighing 100 gm were anesthetized and the inferior surface of each hemimandible was surgically exposed. A slow‐speed dental hand drill was used to drill a small hole through the alveolar bone overlying the secretion or maturation zones of the enamel organ. The wound was closed and during recovery the mechanical trauma to the underlying tissue moved away from the hole due to the continuous eruption of the tooth. Two to 5 days later the hole was reexposed and microinjections of 3H‐proline, 125I‐salmon calcitonin, vinblastine sulphate, and normal saline (as control) were administered through the hole with a micro‐manipulator and a microliter syringe. Radioautographic detection of 3H‐proline incorporation in secretory ameloblasts and enamel at 10 minutes, 30 minutes, 1 hour, 4 hours, 1 day, and 2 days after microinjection was identical to that obtained previously by systemic injection. Two hours after microinjection of vinblastine sulphate the cellular response was again identical to that following systemic injection; 125I‐salmon calcitonin (M.W. ∼ 3,600D) was used as a molecular weight marker and was seen to diffuse into the enamel of the maturation zone at 10 minutes after microinjection. This study has demonstrated the feasibility of this new technique for experimentation on rat incisor enamel organs.
The external genitalia of female pygmy chimpanzees
Authors: Dahl Jeremy F. 
Published: February 2005

AbstractThe external genitalia of four adult female pygmy chimpanzees (Pan paniscus) were examined during a 2‐year period. It was found that the labia majora are retained in adults of this species and that, when tumescent, the labia minora effectively relocate the frenulum and clitoris so that they point anteriorly between the thighs. When detumescent, the configuration of the labia minora and clitoris resembles that of immature common chimpanzees (P. troglodytes). It is suggested that the simple, structural relocation of the clitoris from the normal condition noted in adult P. troglodytes makes possible the homosexual, intergenital rubbing observed in P. paniscus, when ventroventral juxtaposition of the individuals permits eye‐to‐eye contact. In addition, this change probably increases sexual stimulation of the female during heterosexual, ventroventral copulations. The possibility of intense, face‐to‐face sexual interactions has been achieved by P. paniscus without the evolution of bipedalism and the consequent reorientation of the genitalia seen in Homo sapiens.
Effects of pinealectomy and melatonin administration on thyroid follicles of blind syrian hamsters
Authors: Vriend Jerry , Thliveris James A. 
Published: February 2005

AbstractSince previous studies have shown that an active pineal gland exerts an inhibitory effect on circulating levels of thyroxin in the Syrian hamster, a study was conducted to determine whether the histology and ultrastructure of the thyroid gland supported the conclusions drawn from the hormone data. The ultrastructure of thyroid glands of blinded male Syrian hamsters was compared to that of intact controls kept under a 14L/10D photoperiod, to that of blinded hamsters also pinealectomized, and to that of blinded hamsters receiving 80 μg/ml of melatonin in the drinking water. Serum thyroxin (T4) and serum thyrotropin (TSH) concentrations were determined by radioimmunoassay. After 10 weeks serum thyroxin concentrations were less than 50% of controls and concentrations were significantly reduced. EM examination revealed that blinded hamsters had an increased number of follicular cells with flattened epithelium and nondilated endoplasmic reticulum compared to intact controls. In blinded hamsters that were pinealectomized or treated with melatonin in the drinking water, the ultrastructure of the thyroid was not different from controls and serum thyroxin concentrations were restored to near normal. These ultrastructural data support the conclusion that the pineal gland is required to obtain inhibition of the pituitary‐thyroid axis in blinded hamsters and that melatonin has a counter‐inhibitory effect when administered via the drinking water.
The allantois of the north american opossum (didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm
Authors: Krause William J. , Harry Cutts J. 
Published: February 2005

AbstractDuring the middle of prenatal day 10, the opossum allantois forms as a ventral outgrowth of the hindgut. By day 11 it appears as a large, fluid filled sac and by the middle of day 12 (just prior to birth) it reaches its maximal development. The simple squamous epithelium lining the allantois consists of only one cell type that often contains numerous filaments in the apical cytoplasm. At the luminal surface, the apices of the cells are united by junctional complexes and desmosomes are present between adjacent cells. The luminal surface is irregular, whereas laterally and basally the cell membranes show few if any infoldings. Mitotic figures and presumptive degenerating cells occasionally occur in the allantoic epithelium which rests on a delicate basal lamina. The allantois is covered by a simple squamous mesothelium that lacks a distinct basal lamina. Between the two epithelial sheets lie mesenchymal cells, collagen fibers, and blood vessels. No specializations of cell membranes were noted in either of the epithelial layers. The yolk sac endoderm consists of a single layer of squamous cells whose cytoplasm contains scattered profiles of rough endoplasmic reticulum and mitochondria. Extensive lateral and basal infoldings of the plasmalemma were not observed in these endodermal cells. The morphology of the trophectodermal (trophoblastic) cells indicates a cell type that is active in the transport of materials. Since the endodermal cells that line the allantois lack morphological features that would suggest the presence of mechanisms for transport or exchange, and because they remain relatively unchanged throughout pregnancy, it is thought that the allantois functions primarily in the storage of urinary wastes during prenatal life. As the allantois does not establish physical contact with the yolk sac placenta, it is believed that exchange between the developing fetus and mother occurs primarily through the activity of cells that form the trophoblast.
A comparison of histopathologic changes following x‐irradiation of mid‐thoracic and lumbosacral levels of neonatal rat spinal cord
Authors: Heard Jeanne K. , Ann Gilmore Shirley 
Published: February 2005

AbstractLight microscopic changes were studied in the dorsal funiculi of spinal cords from rats irradiated (4000 R) at 3 days of age and killed from 9–60 days postirradiation (P‐I). The irradiated site was limited to a 5‐mm length of mid‐thoracic spinal cord (T only) in one group of rats, to a 5‐mm length of lumbosacral spinal cord (L only) in a second group, and to 5‐mm lengths of both mid‐thoracic and lumbosacral spinal cord (T/L) in the third group. Changes in the lumbosacral regions were essentially the same in both L only and T/L irradiated groups. These changes included a decreased neuroglial population and a concurrent state of hypomyelination from 9–30 days P‐I. In contrast, in the mid‐thoracic regions of T only and T/L irradiated groups the decrease in the neuroglial population was obvious only through 13 days P‐I, and by 30 days this population resembled that of the controls. The irradiated mid‐thoracic areas were hypomyelinated, with the fasciculus gracilis showing a greater degree of hypomyelination than the fasciculus cuneatus. By 25 days P‐I, myelination appeared to be normal in these areas. Scattered hemorrhages were noted in both lumbosacral and mid‐thoracic regions, but necrotic areas occurred only at the lumbosacral level. In general, the mid‐thoracic area appeared to be less sensitive to x‐radiation at 3 days of age than the lumbosacral area. These data suggest that there may be marked differences in the developmental states of cells at these two levels at 3 days of age.
Asymmetry of the human skull during fetal growth
Authors: Trenouth M. J. 
Published: February 2005

AbstractAsymmetry of the human skull in the frontal and basal views has been described previously as a normal feature in adults. However, no investigation has been performed during the fetal period to see when asymmetry first develops. Previous quantitative methods for measuring asymmetry have relied upon defining anatomical points and using geometrical constructions. In the present study image outlines and their centroids (centers of area) were related to each other via a rectangular coordinate reference grid using the technique of morphanalysis. The centroids were shifted to the left relative to the coordinate reference grid indicating a left side expansion. Also the signed area under the cyclical curve, which is zero for a perfectly symmetrical shape, showed a negative shift indicating asymmetry. The cranium was found to be the major site of asymmetry caused by unequal development of the cerebral hemispheres. The asymmetrical development of the temporal lobes caused a greater displacement of the nasomaxillary segment on the left leading to a rotation of the face on the cranium.
Morphology of the distal conducting airways in rhesus monkey lungs
Authors: Tyler Nancy K. , Plopper Charles G. 
Published: February 2005

AbstractThis study systematically characterizes the organization and nature of epithelial populations in the distal airways of the adult rhesus monkey. Infusionfixed lungs were evaluated using airway dissection and scanning and transmission electron microscopy. We found that a true bronchiole free of cartilage and alveolar outpockets was not consistently present. Cartilage and alveolar outpocketings were often observed within the same airway generation. The epithelial population of nonalveolarized terminal conducting airways was pseudostratified columnar, consisting of ciliated, mucous, and basal cells. The respiratory bronchiole found immediately distal to the terminal conducting airways had two clearly demarcated zones of distinctly different epithelial populations. Overlying the pulmonary artery was the same pseudostratified ciliated columnar epithelial population observed in nonalveolarized terminal airways. The epithelial population in the remainder of the respiratory bronchiole, not associated with the pulmonary artery, was simple nonciliated cuboidal with a few squamous cells. The cuboidal nonciliated bronchiolar cell differs from the mucous cell by having few small granules and rough and smooth endoplasmic reticulum. The extension of the ciliated, mucous, and basal cells several generations into the respiratory bronchiole in rhesus monkey has not been observed in rodents and other laboratory mammals. Data from studies of human airways, although not explicit, suggest that the rhesus monkey epithelial cell pattern resembles the pattern in the human terminal airways.
Decidua‐associated changes in guinea pig uterine blood flow and volume: Relation to uterine norepinephrine concentrations
Authors: Garris David R. , Dar M. S. 
Published: February 2005

AbstractChanges in uterine blood flow (UBF) and uterine blood volume (UBV) during decidual tissue (DT) formation in the guinea pig were assessed at 2, 6, and 10 days postuterine trauma (PT). Uterine weight increased steadily between days 2 and 10 PT in DT‐bearing animals as compared with the constant uterine weights observed in controls. Both UBF and UBV levels were elevated between days 2 and 10 PT in DT‐bearing animals as compared with controls with the vascular changes being histologically related to the progressive stromal differentiation. Uterine norepnephrine (NE) levels were significatly (P ≤ 0.05–0.01) depressed in the hyperemic, DT‐bearing uteri as compared with controls. These results indicate that the uterine hyperemia associated with DT formation in the guinea pig involves a sustained increase in uterine vascular volume as well as vascular perfusion rate under conditions of depressed uterine NE levels. These events are intimately associated with the support of stromal differentiation in the guinea pig.
Morphometry of postnatal development in the porcine lung
Authors: Winkler Gian C. , Cheville Norman F. 
Published: February 2005

AbstractAlveolar regions of normal pig lungs (newborn to 60‐day‐old) were characterized morphometrically to provide a basis for comparison in future investigations of porcine respiratory diseases. Endotracheal installation of fixative was done to expand the lungs uniformly at total capacity. Differential effects of lobar variations were determined by stratified random sampling of lung lobes. A stereologic study was done by point and intersection counts on electron micrographs. At birth, the lungs were remarkably well developed. Relative alveolar and capillary surface densities and air‐blood tissue barrier thicknesses were at adult levels. In allometric regressions, volumes and surfaces of lung components regressed directly to lung volume, but monoexponentially (to the 3/4 power) with body weight. In the first postnatal week, however, relative volume densities of cellular interstitium in septal tissue and of capillary lumina in parenchyma increased at statistically significant levels. Composition of lung parenchyma and septa was changed, although without statistically significant direct impact on parameters related to gas exchange. Type II pneumocytes had increased nuclear to cytoplasmic volume ratios in 7‐ to 14‐day‐old pigs, probably reflecting cell activation and increased surfactant production. Age (postnatal lung growth) created the most substantial variance of results; interanimal variation in pigs of the same age was less important and no consistent lobar variations were seen.
Ruthenium red staining of vaginal epithelial cells and adherent bacteria
Authors: King Barry F. 
Published: February 2005

AbstractThe vaginal epithelium of the rhesus monkey is a keratinized stratified squamous epithelium throughout the menstrual cycle and early pregnancy. The superficial cells have a thickened cell envelope, surface microridges, and numerous adherent bacteria. During later pregnancy the cells mucify and have a typical cell membrane, microvilli, and no adherent bacteria. In the present study we have extended these observations by examining vaginal surface structures after ruthenium red staining. Throughout the cycle, the superficial cells have a thin layer of stained material closely associated with the cell membrane, but in some cases a much thicker mucous blanket was observed. During later pregnancy the epithelial cells had a moderately thick, somewhat clumped ruthenium red‐positive material associated with the cell membrane. Glycocalyx components of the surface of many bacteria also stained with ruthenium red. The adherence of many types of bacteria to the vaginal epithelial cells appears to be effected by the interaction of polyanionic components on the surface of both the bacterial and epithelial cells.
Distribution and characterization of anionic sites in the basal lamina of developing human amniotic epithelium
Authors: King Barry F. 
Published: February 2005

AbstractWe have studied the distribution of anionic sites in the basal lamina of developing human amniotic epithelium by using the cationic stain ruthenium red. Amnions at 7–12 weeks of gestation and at term contained ruthenium redpositive granules in a quasi‐regular array on both the cellular and interstitial sides of the lamina densa. In order to characterize the anionic sites, small pieces of amnion were incubated in the presence or absence of either chondroitinase ABC, neuraminidase, Streptomyces hyaluronidase, or heparitinase in appropriate buffer systems. Incubation in the presence of heparitinase resulted in the complete disappearance of the basal lamina‐associated granules, but other enzymes tested had no demonstrable effect on these granules. We conclude that the anionic sites associated with amnion basal lamina, and demonstrable with ruthenium red, consist of glycosaminoglycans rich in heparan sulfate, probably present as heparan sulfate proteoglycan. Because amniotic fluid has a low protein content and amniotic epithelium (at least at term) lacks tight junctions, we postulate that the heparan sulfate proteoglycan associated with the amnion basal lamina may have an important function as a permeability barrier to anionic macromolecules.
Functional differences between sinusoidal endothelial cells and interlobular or central vein endothelium in rat liver
Authors: Yokota S. 
Published: February 2005

AbstractThe fine topological relationship between sinus‐lining endothelial cells (SLE) and vessel‐lining endothelial cells (VLE) at the opening portion of sinusoids into central or interlobular veins of rat liver was studied by a comparison of morphological and functional properties of both types of cells. Three minutes after intravenous injection of formalin‐denatured albumin conjugated with horseradish peroxidase (HRP‐FDA), liver was perfused with fixative. Chopped sections of the liver (50 μm thick) were incubated in diaminobenzidine‐H2O2 medium, followed by processing for electron microscopy. The HRP‐FDA was localized in endocytotic vesicles and vacuoles of the SLE and Kupffer cells but not of the VLE lining interlobular or central veins or interlobular arteries. In the opening portion of the sinusoids into these veins, the attenuated cytoplasmic extensions of the SLE containing positive vesicles were in direct contact with squamous process of the VLE having no positive vesicles. The contact was mediated by overlapping junctions. No intermediate cell type between the SLE and VLE in this region or other portions was noted. The results indicate that the habitat of the SLE is exactly isolated from that of the VLE in rat liver and at the transitional portion from sinusoids to veins or arteries they are directly connected with each other by overlapping junctions.