bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstration of differential immunohistochemical localization of the neuron‐specific enolase antigen in rat pinealocytes
Authors: McClure Chalmer D. , McMillan Paul J. , Miranda C. Alfonso
Published: February 2005

A refined method for the immunohistological demonstration of neuron‐specific enolase (NSE) on 1‐ to 2‐μm Epon‐812 section gave characteristic staining of cerebral and cerebellar neurons. This method has made it possible to obtain a more detailed characterization of the heterogeneity of rat pinealocytes in the superficial portion of the rat pineal complex. Thirty adult male rats have been studied, five of which were used in a photometric analysis of the distribution of NSE. Pinealocytes stained either intensely or weakly for the NSE antigen and exhibited an uneven distribution within a given region. Further analysis of the gland revealed a distal to proximal decrease in stain intensity. It is suggested that the more strongly stained cells, being concentrated distally, are under sympathetic control.
Ultrastructure of the submandibular gland in the rabbit
Authors: Toyoshima Kuniaki , Tandler Bernard
Published: February 2005

The secretory endpieces of the rabbit submandibular gland are unusual in that they consist of seromucous acini (not demilunes) that empty into serous tubules that in turn drain into intercalated ducts. Seromucous granules consist of a moderately dense spherule in a fibrillogranular matrix. Serous granules contain a feltwork of filaments, which are liberated as a tangled skein during exocytosis. Peculiar granulated cells that have secretory granules of complex morphology are present at each end of the serous tubules. Intercalated ducts are, cytologically speaking, relatively simple, but the duct cells may contain a few oblong secretory granules. Striated ducts are typical in structure, although postfixation with ferrocyanide‐reduced osmium reveals significant amounts of glycogen in the basal processes. Modified mitochondria are present in striated duct cells, but their frequency varies from rabbit to rabbit. Such mitochondria contain either an array of parallel, rigid cristae linked by intermembranous bridges, or a bundle of helical filaments within an expanded crista. Interspersed with the striated duct cells, especially near the duct origin, are some highly vacuolated cells with sparse mitochondria. Excretory ducts consisting of stratified columnar (sometimes pseudostratified) epithelium often show bleb formation of the luminal surface of the tall cells.
The renal cortical lymphatic system in the rat, hamster, and rabbit
Authors: Niiro George K. , Jarosz Harriet M. , O'Morchoe Patricia J. , O'Morchoe Charles C. C.
Published: February 2005

Rat, hamster, and rabbit renal cortical lymphatics were examined by light and electron microscopy. Rat and hamster kidneys possessed both intra‐ and interlobular lymphatics that were structurally similar at the light microscopic level. Ultrastructural examination of the hamster lymphatic endothelium, however, revealed an unusual arrangement of cytoplasmic extensions not seen in the other two species. The intralobular lymphatics were related primarily to tubules, afferent arterioles, and renal corpuscles and were consistent with lymph formation from both plasma filtrate and tubular reabsorbate. Interlobular lymphatics were seen in connective tissue associated with the interlobular blood vessels. Rabbit cortex contained only interlobular lymphatics. Cross‐sectional area, maximum diameter, volume density, and profile density were determined by stereological measurements using a computer‐based image analyzer. The morphological data from the rat were used, in combination with published values for lymph flow, to calculate the rate of lymph formation per unit area of endothelium in lymphatics of the renal cortex. Among kidneys fixed by retrograde perfusion, the cortical lymphatic system was most extensive in maximum diameter, volume density, and profile density. It was smallest in the rabbit and intermediate in the rat. Lower volume and profile density were found for rat kidneys fixed by the dripping technique. It was concluded that: (1) tubular reabsorbate probably contributes to renal lymph in the rat and hamster, but not in the rabbit; (2) significant differences exist in the extent of the renal lymphatic systems among the three species, with the hamster kidney having the richest network and the rabbit the poorest; (3) the method of fixation influences the measured size and density of renal cortical lymphatics; and (4) the estimated rate of lymph formation in the kidney of the rat is roughly comparable to that in the dog.
In vivo exocytosis of lysosomes by the endothelium of the venous sinuses of bone marrow and liver: Visualization at normal and low body temperature
Authors: De Bruyn Peter P. H. , Cho Yongock
Published: February 2005

We have visualized the exocytosis of lysosomes into the peripheral circulation by the phagocytic endothelia of the venous sinuses of liver and bone marrow of rats. Perfusion fixation at normal body temperature produced images of the earliest stages of lysosomal exocytosis. After fixation at low body temperatures (7–12°C), advanced stages of this process became evident, showing extrusion of lysosomes and their contents into the circulation. It is postulated that this form of exocytosis has escaped structural detection because of its rapidity and relative infrequency as compared to merocrine secretory exocytosis, and that fixation at low body temperatures arrests or slows down these exocytic events in sufficient measure for ultrastructural visualization. The possibility that this lysosomal exocytosis contributes to the presence of lysosomal enzymes detected in the peripheral blood should be considered. In addition, it is likely that lysosomal degradation products may be discharged by exocytosis into the circulation.
Scanning electron microscopy of isolated epithelium of the murine gastrointestinal tract: Morphology of the basal surface and evidence for paracrinelike cells
Authors: Magney J. E. , Erlandsen S. L. , Bjerknes Matthew L. , Cheng Hazel
Published: February 2005

By using the method of Bjerknes and Cheng, isolated murine gastrointestinal epithelial sheets were prepared for scanning electron microscopy. Examination of isolated epithelium from fundic stomach revealed numerous branched gastric glands. Parietal cells were easily detected bulging from the basal surface of the glandular epithelium. The basal surface membrane of parietal cells appeared smooth, with only sparse microvilluslike projections, whereas adjacent glandular cells had numerous 1‐ to 2‐μm fingerlike projections which interdigitated laterally with similar processes from adjacent cells. Occasionally, paracrinelike cells having long cytoplasmic processes ranging from 10 to 20 μm in length were observed on the basal epithelial surface of the stomach and the colon, but not the small intestine. In isolated intestinal epithelia, the basal surface of crypt epithelial cells showed extensive cytoplasmic interdigitations, but no distinct morphology permitting recognition of individual cell types. Various stages of intestinal crypt bifurcation were seen. Craterlike spaces in the basal surface of crypt epithelium, presumably due to migrating leukocytes, were also numerous. Examination of the luminal surface of the isolated intestinal epithelium revealed that intimate associations between epithelium and mucosal‐associated microorganisms were maintained, thus suggesting that minimal alterations in surface morphology were incurred by epithelial isolation. These observations on epithelial structure suggest that isolated gastrointestinal epithelia may be well suited for physiological studies of epithelial function and interactions with the microbial flora.
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

Previous 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

The 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

Peroxisomes, 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

The 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

The 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

We 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

The 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

The 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

This 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

The 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

Twenty‐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

The 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.
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

3H‐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

The 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

Scanning 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

Osteopetrosis 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

Chronic 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

Serial 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

Pancreatic 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

Several 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

Efferent 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.