bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of myocardial tissue components and cardiocyte organelles in pressure‐overload hypertrophy of the cat right ventricle
Authors: Lauva Ines K. , Brody Eric , Tiger Eric , Kent Robert L. , Cooper George , Marino Thomas A. 
Published: February 2005

AbstractPrevious studies have demonstrated that there is a disproportionate increase in connective tissue in right ventricular myocardium subjected to pressure‐overload hypertrophy associated with depressed cardiac contractility. While the myocardium is primarily responsive to load, the aim of the present study was to determine whether catecholamines also modulate the response of myocardial tissue components and cardiocyte organelles in pressure‐overload‐induced cardiac hypertrophy. Four experimental groups of cats were examined: (1) a sham‐operated control group, (2) a group which had their pulmonary arteries banded in order to induce a pressure overload, (3) a group which had been subjected to the same pressure overload, but in addition had β‐adrenoceptor blockade produced prior to and during the pressure overloading, and (4) a group which had been subjected to the same pressure overload, but in addition had α‐adrenoceptor blockade produced prior to and maintained during the pressure overloading. As in our previous study, there was a significant and equivalent degree of right ventricular hypertrophy in all experimental groups with pressure overload when assessed either as the ratio of right ventricular weight to body weight or as cardiocyte cross‐sectional area. At the light microscopic level, the disproportionate increase in the volume density of myocardial connective tissue seen in banded animals was completely prevented by either α‐ or β‐adrenoceptor blockade. At the electron microscopic level, there was a reduction in the mitochondrial and myofibrillar volume fractions following β‐adrenoceptor blockade. The results of this study provide evidence for a modulatory role of catecholamines in the control of myocardial connective‐tissue proliferation in pressure‐overload‐induced cardiac hypertrophy. There is also evidence to support the role of the adrenergic nervous system in regulating cardiocyte subcellular organelles, independent of the regulation of cardiocyte size.
Proliferation of human embryonic and fetal epidermal cells in organ culture
Authors: Bickenbach J. R. , Holbrook K. A. 
Published: February 2005

AbstractThe morphology of human embryonic and fetal skin growth in organ culture at the air‐medium interface was examined, and the labeling indices of the epidermal cells in such cultures were determined. The two‐layered epidermis of embryonic specimens increased to five or six cell layers after 21 days in culture, and the periderm in such cultures changed from a flat cell type to one with many blebs. The organelles in the epidermal cells remained unchanged. Fetal epidermis, however, differentiated when grown in this organ culture system from three layers (basal, intermediate, and periderm) to an adult‐type epidermis with basal, spinous, granular, and cornified cell layers. Keratohyalin granules, lamellar granules, and bundles of keratin filaments, organelles associated with epidermal cell differentiation, were observed in the suprabasal cells of such cultures. The periderm in these fetal cultures formed blebs early but was sloughed with the stratum corneum in older cultures. The rate of differentiation of the fetal epidermis in organ culture was related to the initial age of the specimen cultured, with the older specimens differentiating at a faster rate than the younger specimens. Labeling indices (LIs) of embryonic and fetal epidermis and periderm were determined. The LI for embryonic basal cells was 8.5% and for periderm was 8%. The fetal LIs were 7% for basal cells, 1% for intermediate cells, and 3% for periderm. The ability to maintain viable pieces of skin in organ culture affords a model for studying normal and abnormal human epidermal differentiation from fetal biopsies and for investigating proliferative diseases.
Stereological analysis of peroxisomes and mitochondria in intestinal epithelium of patients with peroxisomal deficiency disorders: Zellweger's syndrome and neonatal‐onset adrenoleukodystrophy
Authors: Black Virginia H. , Cornacchia Louis 
Published: February 2005

AbstractPeroxisomes, participants in lipid metabolism, have been shown to be altered in liver in two metabolic diseases in which long‐chain fatty acids accumulate in tissues: Zellweger's syndrome and neonatal adrenoleukodystrophy (ALD). The intestine also plays a role in lipid metabolism, and we have had the opportunity to compare peroxisomes in normal intestinal epithelium with those from patients with Zellweger's syndrome and neonatal ALD at the electron microscopic level by using the combined techniques of cytochemistry and stereological analysis. Peroxisomes were numerous in intestinal epithelium of the normal individuals. They were ellipsoidal in shape with average diameters of 0.37 by 0.56 μm and filled with coarsely granular, DAB + content. Peroxisomes in the intestinal epithelium of the ALD patient were similar in appearance and number but smaller in size (0.28 by 0.44 μm). Peroxisomes of normal appearance were absent from the intestinal epithelium of patients with Zellweger's syndrome; DAB + content, however, was observed in rare, membrane‐bound structures of much smaller size (0.12 by 0.19 μm). In liver of patients with Zellweger's syndrome, peroxisomes are lacking; in neonatal ALD they are abnormal in appearance and greatly reduced in number. The presence of rare minute peroxisomes in the intestinal epithelium in Zellweger's syndrome and of small peroxisomes in this epithelium in neonatal ALD indicate that peroxisomes in the intestinal epithelium are affected in these diseases, but to a lesser extent than in the liver. In the ALD intestinal epithelium, DAB + material was also seen in long, sinuous, tubular or cisternal elements intermingled and occasionally in continuity with peroxisomes. It is suggested that these represent the early stages of peroxisome formation, the peroxisomal reticulum as originally envisioned by Lazarow, while the rare structures seen in Zellweger's represent rudiments of such a reticulum. Lamellar inclusions and clear spaces occurred in the cytoplasm adjacent to these structures indicating either that material accumulated there had been extracted during fixation or that these regions are more susceptible to autolysis. Mitochondria are also involved in lipid metabolism and have been reported to be abnormal in Zellweger's tissue. No qualitative differences were observed in the mitochondria of the intestinal epithelia examined in this study. Although quantitation revealed a greater mean volume, number, and surface density of mitochondria in the intestinal epithelia of neonatal ALD, it was not a statistically significant difference in all cases.
Enzymatic differentiation of arterial and venous segments of the capillary bed during the development of free muscle grafts in the rat
Authors: Grim Miloš , Mrázková Olga , Carlson Bruce M. 
Published: February 2005

AbstractThe revascularization of freely grafted muscles in the rat was studied by histochemical reactions that on frozen sections stain the arterial part of the capillary bed blue (alkaline phosphatase [AP] reaction) and the venous part of the capillary bed red (dipeptidyl peptidase IV [DPP IV] reaction). In 112 rats the extensor digitorum longus or soleus muscles were freely grafted and removed at various times up to 93 days following the surgery. In cross section, the capillaries of a normal muscle show a mosaic pattern of staining for the activity of the two enzymes. After grafting, DPP IV activity of capillaries is lost throughout the entire graft within a day or two; but within ischemic muscle, weak and diffuse AP staining persists in capillary remnants for up to 6 days. In the very periphery of the graft AP staining is also preserved in partially damaged capillaries. By 4 days, new AP‐positive capillaries can be identified at the periphery of the graft, and in succeeding days AP‐positive capillaries are found progressively nearer the center of the graft. At 7 days, the capillary/muscle‐fiber ratios are 66% of normal in the periphery of the graft and 44% in the intermediate zone. DPP IV‐stained capillaries are not seen until 7 days after grafting. By 60 days, when the grafts have become stabilized, the mosaic pattern of capillary staining has become reestablished. In mature grafts, the number of capillaries per unit area was slightly higher than that in control muscles, but the capillary/muscle‐fiber ratio was slightly lower, owing to the smaller than normal cross‐sectional areas of the regenerated muscle fibers.
Differentiation of the embryonic disc, amnion, and yolk sac in the rhesus monkey
Authors: Enders Allen C. , Schlafke Sandra , Hendrickx Andrew G. 
Published: February 2005

AbstractThe inner cell mass of the blastocyst has differentiated into epiblast and hypoblast (primitive endoderm) prior to implantation. Since endoderm cells extend beyond the epiblast, it can be considered that both parietal and visceral endoderm are present. At implantation, epiblast cells begin to show marked evidence of polarity. They form a spherical aggregate with their basal ends toward the basal lamina and apical ends toward the interior. The potential for an internal space is formed by this change in polarity of the cells. No cytological evidence of separation of those cells that will form amniotic epithelium from the rest of the epiblast is seen until a cavity begins to form. The amniotic epithelium is originally contiguous with overlying cytotrophoblast, and a diverticulum remains in this position during early development. Epiblast forms a pseudostratified columnar epithelium, but dividing cells are situated toward the amniotic cavity rather than basally. The first evidence of a trilaminar disc occurs when a strand of cells contiguous with epiblast is found extending toward visceral endoderm. These presumptive mesoderm cells are undifferentiated, whereas extraembryonic mesoderm cells are already a distinct population forming extracellular materials. After implantation, visceral endoderm cells proliferate forming an irregular layer one to three cells thick. Visceral endoderm cells have smooth apical surfaces, but very irregular basal surfaces, and no basal lamina. At the margins of the disc, visceral endoderm is continuous with parietal endoderm and reflects back over the apices of the marginal visceral endoderm cells. This sacculation by visceral endoderm cells precedes pinching off of the secondary yolk sac from the remaining primary yolk sac.
Distribution of lectin receptors in postimplantation mouse embryos at 6–8 days gestation
Authors: Kimber S. J. 
Published: February 2005

AbstractWe have examined the pattern of binding of eleven lectins—BSL‐II, WGA, LPA, Con A, DBA, SBA, LTA, UEA‐I, MPA, PNA, and RCA‐I, with specificity for a range of saccharides, to postimplantation mouse embryos from 6 to 8 days of gestation. The lectins were used to stain sections of ethanol‐fixed paraffin‐embedded and formaldehyde‐fixed gelatin‐embedded embryonic material. Our observations reveal a complex pattern of lectin binding to both cell surfaces and cytoplasm. Many of the lectins bind particularly to the outer surface of visceral endoderm (e.g., DBA, WGA, SBA, and RCA‐I) and to the surface of the proamniotic cavity (e.g., RCA‐I, PNA, and WGA). In the newly formed mesenchyme of primitive‐streak‐stage embryos, galactose and N‐Acneuraminic acid are present but lectins with specificity for other sugars either did not bind to the cells or bound only in small amounts.
Microscopic and submicroscopic anatomy of the parabronchi, air sacs, and respiratory space of the budgerigar (Melopsittacus undulatus)
Authors: Smith Jerome H. , Meier Judy L. , Lamke Cheryl , Neill P. J. G. , Box Edith D. 
Published: February 2005

AbstractThe normal microscopic and submicroscopic structure of the lower respiratory tract of the budgerigar (Melopsittacus undulatus) is described and compared with other birds and mammals. Granular (type II) pneumocytes are confined to linings of air sacs, parabronchi, and their atria; however, their secretions (surfactant) cover the surfaces of the infundibula and respiratory space. Infundibula extend from the atria and give rise to the air capillaries, which branch and anastomose freely with those of adjacent infundibula and other parabronchi (interparabronchial septa are not found). Infundibula and the respiratory labyrinth are lined by a continuous epithelium of squamous pneumocytes, whose perikarya are concentrated in the infundibula and whose peripheral cytoplasm is markedly attenuated. The squamous pneumocytes of the respiratory labyrinth share a basal lamina with the blood capillaries that they envelop.
Evolution of the endoplasmic reticulum during spermiogenesis of the rooster: An electron microscopic study
Authors: Xia L. , Clermont Y. , Lalli M. , Buckland R. B. 
Published: February 2005

AbstractThe endoplasmic reticulum (ER) of rooster's spermatids was analyzed during spermiogenesis, which was subdivided into eight distinct steps on the basis of changes observed with the electron microscope in the nucleus, acrosome‐perforatorium system, manchette, and flagellum. In steps 1 and 2, spermatids' ER cisternae presented the following specializations: (1) A loose network of tubular cisternae was distributed throughout the cytoplasm. (2) Six to eight tight networks of anastomosed tubular cisternae parallel to each other were closely stacked to form a discoid body (1.5–2.5 μm in diameter and 0.5–0.8‐μm thick) in which spheroidal vesicles (0.4 μm in diameter) were inserted. Close to and connected with this body, called the alveolar body, there was a stack of annulate lamellae. (3) Large, flattened ER cisternae were seen singly or in piles of two or three running parallel to the nuclear surface. (4) A collection of tubular ER cisternae faced plaques of thickened plasma membranes. These elements of the ER system appear continuous with each other. During steps 3–5 of spermiogenesis, no modification of the alveolar body‐annulate lamellae complex was noted; the large flattened ER cisternae disappeared, however, and the broad network of tubular cisternae developed markedly. During steps 6 and 7, the latter network of tubular cisternae fragmented into vesicles that swelled to give a vacuolated appearance to the cytoplasm. The alveolar body‐annulate lamellae complex remained visible until late step 7, when it disintegrated just before spermiation. Thus the system of ER cisternae underwent marked structural modifications during spermiogenesis.
The stroma of the thymus of the rat: Morphology and antigen diffusion, a reconsideration
Authors: Sainte‐Marie G. , Peng F.‐S. , Marcoux D. 
Published: February 2005

AbstractThis work reconsiders aspects of the morphology of the capsule, of the blood vasculature, of the distribution of reticular fibers, and of the diffusion of intramediastinally injected antigens in the stroma of the thymus of the rat. This was done by an analysis of standard sections of normal thymuses, of sections of thymuses perfused with colloidal carbon, of silverimpregnated sections, and of sections of thymuses of rats injected intramediastinally with a fluorescent antigen or intravenously with Trypan blue, and by electron microscopy of the thymic capsule. The capusle consisted of two layers: an outer layer covering the entire periphery of a thymic lobe, and an inner layer which outlined the entire convoluted peripheral cortex of a lobe. Cortical vessels entered the capsule and septa in which they formed a capillary network. These capsular capillaries were fenestrated and leukocytes were often present near them. Adipocytes were also seen near these vessels in some areas of the capsule and often at the bases of septa and trabeculae. Furthermore, much of the medulla had a dense network of coarse reticular fibers, whereas the remainder of the medulla and the cortex contained a loose network of fine fibers stretching out from the capsule, septa, and trabeculae. Intramediastinally injected flourescent antigens were observed to spread in the capsule and septa and to diffuse in the fiber networks stretched across the cortex and the medulla. Fluorescence also highlighted cortical reticular cells but not the thymocytes. Intravenously injected Trypan blue stained the capsule, the septa, the cortical reticular cells, and the autofluorescent cells outlining the corticomedullary junction of each lobule. The unusual penetration of capillaries from the thymic parenchyma into the thymic capsule suggested that the capsular capillaries participate in peculiar thymic events, such as the recruitment of blood stem‐cells. It is concluded that small amounts of blood antigens normally exude from capsular capillaries and diffuse into the fibers extending from the capsule across the cortex. The phenomenon would be increased under conditions causing thymic involution. An explanation is proposed to account for the development of involution which involves the exudation of antigens from the capsular capillaries. A comparable mechanism could also account for the development of a particular experimental immune tolerance.
Comparative morphology and evolution of the otic region in toothed whales (Cetacea, Mammalia)
Authors: Oelschläger Helmut A. 
Published: February 2005

AbstractThe otic region in the skull of archeocetes and odontocetes is compared and interpreted with special emphasis on the morphology and suspension of the ear bones. In archeocetes, the periotic was obviously separate from the mastoid but still integrated within the skull via a long anterior and posterior process. The rotation of the cochlear part of the periotic was already obvious. The tympanic bone was attached to a decreasing number of neighboring elements, with the periotic becoming more and more important in the later archeocetes. The accessory air sacs of the tympanic cavity had invaded some of the adjacent skeletal elements and attained a moderate‐to‐remarkable extension. In the evolution of the odontocetes, the periotic and tympanic were successively uncoupled from the skull and combined to a new morphological and functional unit (tympanoperiotic complex). This uncoupling was mainly achieved by shortening the periotical processes and simultaneously extending the tympanic air sacs. For functional reasons, however, the periotic (posterior process) stayed in immediate contact with the mastoid, the latter remaining in the lateral wall of the skull. In advanced marine dolphins, the bony sheaths of the accessory air sacs are largely reduced, presumably because of volume fluctuations in the tympanic cavity during diving. The perfect uncoupling of the ear bones from the skull obviously was an essential prerequisite for directional hearing, for effective ultrasound orientation and communication, and finally, for the striking development of the dolphin brain.
Regeneration of growth plates in the long bones of the neonatal rat hindlimb
Authors: Libbin Richard M. , Weinstein Martin 
Published: February 2005

AbstractTwenty‐seven male albino rats underwent hindlimb amputations through the lower femur or the midshaft of the tibiofibula on the tenth to 12th day of life. Amputation stumps were examined grossly and histologically in order to assess the significance of level and angle of transection as determinants of subsequent growth and regeneration and to ascertain whether growth plates can regenerate following their complete excision. Amputees survived for 17–73 days. In order to exclude limbs which had been severed at or distal to the level of the growth plate, amputated limb segments either were cleared to transparency and inspected under low magnification or were sectioned serially and examined by using a compound microscope. Following amputations through the femur, the predominant response involved repair of the skeletal defect and healing of adjacent soft tissues (ten of 17 rats). Among five other animals the skeletal terminus was covered with a plate of cartilage which, in three, included areas of growth‐plate architecture. Two additional transfemoral amputees regenerated incomplete growth plates, each overlying a single epicondylar surface, and one provided with a regenerated hemiepiphysis. Five of ten transtibiofibular amputees formed cartilage plates which covered the skeletal terminus in whole or in part and one regenerated an entire growth plate restricted to the distal fibula. It is concluded that angle and level of transection are not pivotal modifiers of growth and regeneration processes, and that distal growth plates may regenerate entirely or in part following their complete removal from the hindlimb.
Reproduction in the male honey possum (Tarsipes rostratus: Marsupialia): The epididymis
Authors: Cummins J. M. , Temple‐Smith P. D. , Renfree M. B. 
Published: February 2005

AbstractThe epididymis of the adult honey possum, Tarsipes rostratus, is enclosed by a heavily pigmented tunica vaginalis and lies with the testis in a prominent prepenile scrotum. It is connected to the testis by a single ductus efferentis and is lined by approximately equal numbers of cuboidal ciliated and principal cells. It is unusual for marsupials in having no well‐defined compartments or fibrous septae and in having extensive convolutions of the duct only at the caudal flexure. Three principal functional zones (initial, middle, and terminal segments) were identified in the epididymis, based on epithelial type and ultrastructural evidence of sperm maturation. Luminal diameter increases progressively throughout the tract, and epithelial height variations (from about 2 to 20 μm) are greatest in the terminal segment. The epithelium itself is remarkably low (maximum of 21.6 μm) compared with that seen in the epididymis of other mammals. The thickness of the peritubular smooth muscle coat increases close to the junction of the epididymis and ductus deferns. Sperm concentrations were estimated from counts of sperm nuclei and thus can be no more than approximations. The figures are consistent, however, with a rapid increase in concentration in the initial segment, indicating extensive fluid resorption. Sperm concentrations appear to peak in the distal zone of the terminal segment, although sampling problems and wide variations in count make such a conclusion only tentative. Principal and basal cells are the predominant cell types in the epididymal epithelium. Basal cells are most abundant in the initial and distal middle segment. Principal cells show structural evidence of active exchange with the luminal contents and have abundant apical stereocilia, the structure of which depends on the epididymal zone. Other cell types occur less commonly in the epithelium. Lipid‐rich and phagocytic principal cells are restricted to the middle and distal zones of the middle segment, respectively. Clear cells, restricted to the terminal segment, and halo cells were found in very low numbers. As in some other marsupials, principal cells (possibly specialized for this function) selectively remove cytoplasmic droplets and probably other cellular debris from the luminal contents. In Tarsipes, however, this process is not very efficient, and many discarded droplets pass through to the terminal segment where they form large masses of debris associated with aggregates of degenerating spermatozoa.