摘要:

AbstractGene expression for calbindin‐D28k, the 28,000 relative molecular mass vitamin D‐dependent calcium‐binding protein, was measured in cells of the murine nephron by in situ hybridization on tissue sections (hybridization cytochemistry). Radiolabeled (35S‐UTP), single‐stranded RNA complementary to calbinding‐D28k‐mRNA (probe RNA) was prepared from linearized cDNA template and used for the hybridizations. Autoradiography was carried out and cellular levels of hybridization signal (silver grains) were quantified. After corretion for background the concentration of silver grains was more than 350% greater in the distal tubule than in either the proximal tubule or the glomerulus. The relative cellular level of mRNA in the cytoplasm, as reflected in silver grains/cell, of the distal tubules with probe RNA was 3.4 times greater than that with control RNA. Cells of the distal tubule were the only apparent sites of specific hybridization with probe RNA. The presence of calbindin‐D28k‐mRNA in the distal tubule corresponded to the localizations of calbindin‐D28kby

ISSN:0003-276X    

DOI:10.1002/ar.1092270202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study reports the distribution of microfilaments, microtubules, and intermediate filaments in endothelial cells, reticular cells, and macrophages of bone marrow of rats following fixation with glutaraldehyde, tannic acid, and saponin. In endothelial cells bundles of microfilaments are seen along the basal surface, where these cells adhere to underlying extracellular materials. The reticular cells, especially those that are closely associated with the endothelium of sinusoids, contain many intermediate filaments and microtubules as well as microfilaments. The reticular cell processes that partially cover the endothelium and extend among the blood cells have numerous microtubules and intermediate filaments arranged longitudinally within them; these cytoskeletal elements appear to provide mechanical support for the processes. Macrophages also have many microtubules and intermediate filaments but these organelles do not extend into the thin processes of these cells as is the case with reticular cells. Bundles of microfilaments are observed in the cytoplasm of adventitial and endothelial cells at sites where migrating blood cells are attached to these cells producing local regions of stress.

ISSN:0003-276X    

DOI:10.1002/ar.1092270203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study deals with the form and function of the temporomandibular joint capsule and compares the histogical structure of the capsule and kinetics of condylar and disc movement in rabbit and man.The morphology of the capsule of the jaw joint of the rabbit was studied by means of histological sections of isolated capsules, cellodin sections of decalcified heads, and cryostat sections containing the joint, fixed in jaw open and closed positions. General staining methods and selective methods for elastin and collagen were used. The volume density of the elastic fibers was determined morphometrically. The capsule consists of a portion connecting disc and skull and a portion connecting disc and mandible. The former portion has a fibrous outer layer of dense connective tissue. It contains numerous bundles of specifically oriented collagen but hardly any elastic fibers. Few irregularly arranged elastic fibers are present in the lateral and medial areas of the capsule. In contrast, the portion connecting disc and condylar process contains not only oriented collagen but also large amounts of elastic fibers. Anteriorly, there is a thin elastic band that is streched greatly at jaw opening. Posteriorly, the capsule takes the appearance of a large fibro‐elastic pad that covers the posterior extension of the condyle. This part is somewhat stretched when the jaw is closed. The findings correlate well with the results of jaw movement studies, showing a remarkable capability for condylar protrusion and retrusion. In contrast to the situation in humans, this movement occurs mainly between condyle and disc. It is made possible by the rather tight connections between skull and disc and flexible ones between disc and condyl

ISSN:0003-276X    

DOI:10.1002/ar.1092270204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractNomarksi optics were used to identify stages of the spermatogenic cycle of seminiferous tubules in sectioned tissue or in whole dispered tubules and to characterize the equine spermatogenic wave. Embedded tissues were sectioned at 20 μm. Whole dispersed tubules were obtained by enzymatic digestion of thin slices of fresh testis. Dispersed tubules were fixed, dehydrated in graded levels of alcohol, infiltrated with Epon, and mountedin totoon glass slides. Stages of the spermatogenic cycle could be idetified under Nomarski optics in both histologic sections and tubules mountedin toto. Stage dependent nuclear chromatic and cytoplasmic changes in spermatogonica, spermatocytes, and spermatids were evident. Spermatid development included chromatin condensation, nuclear elongation, acrosomal development from the Golgi and proacrosomic granules, migration of the annulus and mitochondrial alignment, and the transient appearance of the chromatoid body and manchette. Both nuclear and cytoplasmic details of Sertoli cells were revealed. In tubules mountedin toto, the spermatogenic wave along the length of the tubules occurred as a consecutive set of stages occupying small regions to that of humans than that of rats. The combination of enzymatic isolation of seminiferous tubules and identification of spermatogenic stages by Nomarski optics facilitates examination of the spermatogenic wave in species whose tubules are tightly bound and not easily teased apart

ISSN:0003-276X    

DOI:10.1002/ar.1092270205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe expression of human growth hormone (GH) in female transgenic mice (TM) is accompanied by sterility, whereas females expressing the bovine GH gene are fertile. A light and electron microscopic study was conducted to examine whether expression of these foreign GH genes in mice is associated with structural changes in the ovaries of young adult (3‐month‐old) or middle‐aged (7‐month‐old) mice. One ovary was serially sectioned for light microscopy, and the contralateral ovary was used for electron microscopy. The numbers of preantral (PAF) and antral (AF) follicles, with and without signs of atresia, as well as the number of corpora lutea (CL), were determined. As expected, body weights of both young and middle‐aged TM of either kind were significantly increased over those of their normal littermates. However, the ovarian weights of TM and control mice did not differ. In the 3‐month‐old TM, the ovaries were grossly normal at the light microscopic level. However, significantly more CL were counted in the ovaries of human GH‐TM than in those of the other two groups. The percentage of PAF with signs of atresia was significantly reduced in ovaries of bovine GH‐TM compared with the other groups, while the percentages of AF undergoing atresia were significantly different in all groups, with the highest values in normal animals, intermediate ones in human GH‐TM, and the lowest in bovine GH‐TM. In the ovaries of 7‐month‐old human GH‐TM, conspicous clusters of large, foamy light cells were present in the cortex and the medulla. Ultrastructurall, these cells appeared as interstitial cells in various stages of degeneration, accumulating cholesterol crystal‐like inclusions. Although degeneration of interstital cells was observed also in the other types of animals, it involved usually only single cells and no cytoplasmic crystal inclusions. Moreover, in the ovaries of 7‐month‐old human GH‐TM the percentages of PAF were significantly reduced and the percentages of AF significantly increased compared with those in the two other groups, which did not differ from each other with respect to these parameters. No significant differences in the numbers of CL were found between the groups. Percentages of atretic PAF were significantly reduced in bovine GH‐TM and comparable in the other two groups, while percentages of atretic AF were not different between normal and bovine GH‐TM, but were significantly increased in human GH‐TM. Our results support the idea that the ovary, although not enlarged in either type of TM, is affected by chronic exposure to heterologous GH. Bovine GH, which in the mouse exhibits isolated somatotrophic activity, reduced the morphological signs of atresia in TM. Human GH, which in the mouse has additional lactotrophic activity, caused complex, age‐related changes, including acceleration of follicular development, increased atresia, and massive degeneration of interstitial cells. These results suggest that the expression of human GH transgene leads to accelerated aging of the mouse ovary and that this effect is likely due to the combination of somatotrophic and lactot

ISSN:0003-276X    

DOI:10.1002/ar.1092270206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractPrevious studies using light microscopy have described the presence of oocytes within the ovarian surface epithelium (OSE) of the neonate ovary and their subsequent release into the periovarian space. The ultrastructural examination and quantitative estimate of oocyte migration through the OSE is described in this study. The surface of the mouse ovary is covered by a simple squamous to simple cuboidal epithelium resting on a distinct basal lamina. Healthy, non‐atretic primordial follicles located in the periphery of the ovarian cortex interact with the OSE. Oocytes within the primordial follicles are large (50–70 μm), spherical cells surrounded by a single layer of squamour granulosa cells. Migratory oocytes initially display a ruffled border and extended pseudopodia like cellular extensions towards the OSE. These processes subsequently compromise the basal lamina of the OSE and extend between the epithelial cells. Granulosa cells retract as junctional complexes between them and the oocyte are no longer observed. The oocyte migrates between the OSE cells and passes into the periovarian space without the loss of either OSE or granulosa cells. The rate of oocyte migration reaches a peak during the first week of neonatal development and then gradually diminishes until by day 28 of development no oocyte migration was obse

ISSN:0003-276X    

DOI:10.1002/ar.1092270207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe migration of intestinal intervillous epithelial cells labeled in the fetus was followed in neonatal mice. At 17 days of gestation, a first group pregnant mice received three intraperitoneal injections of3H‐thymidine (150 μCi/injection) administered at 30 min intervals. Two mothers were sacrificed 3 hours after the first injection. Mice from different litters were also sacrificed on days 0, 2, 4, 8, 12, 14, and 16 after birth. A second group of pregnant mice was injected at 18½ days of gestation and offspring were sacrificed on days 6, 8, 10, 12, 14, and 16 after birth. Segments of duodenum and ileum were fixed in glutaraldehyde, postfixed in osmium tetroxide, dehydrated, and embedded in Epon. Sections were stained with aldehyde fuchsin and processed for radioautography. By following the leading front and trailing edge of labeled cells in the longest villi of the duodenum and ileum, we observed that 1) extrusion zones become active immediately after birth and 2) the longest villi do not elongate until 10 days after birth in the duodenum and 14 days in the ileum, that is, when all labeled epithelial cells originally present in the fetus have been extruded. Moreover, by measuring the distance between the internal limit of the inner circular layer of smooth muscle and the intervillous epithelium at 17 days of gestation (12.95 ± 1.18 μm) or the bottom of the crypts at day 3 (14.81 ± 0.91μm), we propose that crypts do not develop as downgrowth: rather the intervillous epithelium is reshaped and the crypt‐villus junction moves upward, away from the muscularis externa.In conclusion, by analyzing the growth pattern of the longest villi in neonatal mice, we have found that a steady state between cell production and cell extrusion is reached at birth in the duodenum and by day 4 in the ileum. This steady state will be lost however, after day 10, thus enabling lengthening of

ISSN:0003-276X    

DOI:10.1002/ar.1092270208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe development of the rat meninx from the viewpoint of cell proliferation was studied microscopically and immunohistochemically using bromodeoxyuridine (BUdR). A compact cell layer around the neural tube, the meninx primitiva, was observed in 12‐ and 13‐day fetuses. A reticular structure resembling the subarachnoid space appeared in the 14‐day fetus. The ectomeninx, consisting of a collagen fiber layer, part of which became the dura mater, appeared in 15‐day fetuses, allowing discrimination of the endomeninx, the arachnoid cell layer. The primordium of the choroid plexus also appeared in the lateral ventricle on the same day. Bone appeared in the primitive dura mater, and stratification of the meninx was almost complete in 21‐day fetuses. BudR‐positive cells were confirmed in the meninx from day 12 of gestation to day 15 postpartum. The number of BudR‐positive cells was greatest in fetuses aged about 12 or 13 days, reaching nearly 50%, but decreased gradually toward the neonatal period. The findings of this study suggest that, after the migration of neural crest cells, marked cell proliferation in the meninx begins. Differentiation into various layers then follows and is almost complete before birth, whereas the proliferation of arachnoid cells continues even in the early ne

ISSN:0003-276X    

DOI:10.1002/ar.1092270209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe germinal area of the rabbit blastocyst between 108 h postcoitum (pc) and 168 h pc has been examined by scanning electron and transmission electron microscopy. At 108 h and 120 h pc the polar trophoblast (Rauber's layer) is an intact epithelium overlying the epiblast of the inner cell mass. By 132 h pc the polar trophoblast cells begin to separate at multiple foci, exposing the underlying epiblast. Most of the polar trophoblast cells have become individually separated at 144 h pc. The villous, electron‐dense polar trophoblast cells can be easily distinguished from cells for the epiblast, which have smooth apical surface. By 162 h pc the polar trophoblast cells have disappeared from the germinal area.Before the polar trophoblast breaks up, the underlying epiblast cells are only loosely attached to one another. Concurrent with the disintegration of the trophoblast epithelium, the epiblast cells change in shape so that their lateral borders become closely apposed, and juctions develop to form a new epithelium. The epiblast becomes contiguous with the mural trophoblast, and thus the blastocyst does not lose its turgidity as the permeability sea is maintained.There are two classical theories on the fate of the polar trophoblast: the cells die, or they become incorporated into the epiblast as living cells. In newly exposed epiblast the presence of very large phagosomes, which are not found when the polar trophoblast is still intact, favors the first hypothesis and indicates that in the rabbit the epiblast is involved in the phagocytosis of the polar trophoblas

ISSN:0003-276X    

DOI:10.1002/ar.1092270210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractMetaphyseal blood vessels which invade the calcifying epiphyseal growth plate were examined by a variety of techniques to determine their morphology, cell division, and growth patterns as they relate to endochondral ossification. Four regions of these vessels were characterized: 1) sprout tips—the terminal ends of the capillary sprouts which impinge upon the hypertrophic chondrocytes of the growth plate; 2) region of extended calcified cartilage—those deeper vessels within the metaphysis which are surrounded by an extracellular matrix predominantly composed of extended septa of calcified cartilage; 3) region of bone deposition—further still from the epiphysis these microvessels are contained within a network of active bone deposition laid upon a scaffold of calcified cartilage; 4) region of primary vessels—at a distance of 350–500 μm from the epiphysis are dilated vessels with one or two layers of smooth muscle in their walls, which supply and drain the metaphyseal capillary plexus. The sprout tips are continuous blind‐ended vessels lined with an attenuated endothelium with no underlying basement membrane. Dividing endothelial cells are most frequently found in the region of bone deposition 175–200 μm behind the apices of the growing sprout tips. A time‐coursed, autoradiographic examination of cytokinesis revealed radio‐labelled endothelial cells to appear at the epiphysis after a 24 hr period. The metaphyseal capillary sprouts represent a continuous, unidirectional angiogenic vascular network which grows by elongation from the region of bone deposition; this region remians a fixed distance behind the sprout tips. These findings are discussed in light of the growth dynamics between this vascular plexus and the epip

ISSN:0003-276X    

DOI:10.1002/ar.1092270211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY