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11.
The cytoskeleton of isolated murine primitive erythrocytes 总被引:1,自引:0,他引:1
Summary Cytoskeletons of primitive erythrocytes have been isolated from the embryos of day 12 pregnant C57/Bl mice and examined by transmission electron microscopy, immunofluorescence microscopy, and SDS-polyacrylamide gel electrophoresis. Microtubules are the most prominent cytoskeletal component. They are found either singly or organized into loose bundles just under the plasma membrane, but do not form classical marginal bands in most cells. Immunofluorescence with a polyclonal tubulin antiserum confirms this distribution and further reveals numerous mitotic figures among the cells. Rhodamine-conjugated phalloidin and heavy meromyosin labeling reveal that actin is localized in the cortex of the primitive erythrocyte in the form of 6 nm filaments. Antibody directed against avian erythrocyte alpha spectrin demonstrates that spectrin is also found in the cortex. Occasional 10-nm intermediate filaments, observed in the primitve erythrocytes by electron microscopy, are believed to be of the vimentin class based on positive reaction of the cells with vimentin-specific antiserum. In addition, a band in erythrocyte cytoskeletons comigrates in SDS-polyacrylamide gels with vimentin isolated from mouse kidney. Spectrin and actin were also found to be associated with the membrane of primitive erythrocytes when membrane ghost preparations were analyzed by SDS-polyacrylamide gel electrophoresis. 相似文献
12.
Summary Adult mice were found to show regional variation in the epithelial expression of some molecules of the blood-group antigen series. To investigate connective tissue influences on such differences, heterotypic recombinants of epithelia and connective tissues from various regions were prepared and examined using monoclonal antibodies directed against bloodgroup antigens H and Ley. The results indicate that epithelia may maintain a preexisting regionally specific pattern following recombination but that, in some recombinant matches, the connective tissue is capable of signalling redirection of the pattern of expression towards that typical of the epithelium with which it is normally associated.This work was supported by NIH-NIDR RO1-DEO-5190 相似文献
13.
Summary Albino mice were exposed to constant light for 7 days and were then transferred to periodic light. After initial photic damage and partial cell loss, the remaining visual cells recovered and survived as a stable population. Regions of the outer nuclear layer containing 4–6 rows of nuclei were more affected than those containing 6–10 rows. Changes in the synaptic structures in the receptor terminals of these two regions were recorded after varying survival periods. Some of the rod terminals had multiple synaptic ribbons and larger numbers of horizontal cell processes and bipolar cell dendrites. The number of terminals with multiple ribbons increased during recovery in periodic light. Morphometry demonstrated that the perimeters of horizontal and bipolar cell processes within the rod terminals were significantly larger than those in age-matched control mice, especially 4 weeks after recovery; they remained significantly larger than controls after 2 and 3 months. We suggest that partial loss of rod cells within a group of cells that are synaptically related to a common bipolar or horizontal cell results in synaptic growth inside the terminals of the surviving cells. 相似文献
14.
Isolation and culture of cells derived from human cerebral microvessels 总被引:10,自引:0,他引:10
Harry V. Vinters Susan Reave Penny Costello John P. Girvin Steven A. Moore 《Cell and tissue research》1987,249(3):657-667
Summary Microvessels were isolated from non-neoplastic human cerebral cortical fragments resected for treatment of intractable seizure disorder. The microvessels were incubated in modified Lewis medium with 20 or 30% fetal bovine serum. Within 1–2 weeks, two cell populations emerged from the isolates. One type of cells had polygonal morphology, showed density-dependent contact inhibition at confluence in vitro, showed lectin-binding characteristics of endothelium (but only moderate positivity for factor VIII antigen), demonstrated induction of -glutamyl trans-peptidase when exposed to astrocyte-conditioned media, and responded to insulin by a pronounced increase in DNA synthesis. The other variety of cells grew in vitro more slowly in irregular strands separated by clear zones, showed ultrastructural features of smooth muscle, and isoelectric focusing of cell proteins revealed the presence of smooth-musclespecific -isoactin. Both types of cells could be serially subcultured. The ability to isolate and grow the two cell types, tentatively identified as human cerebral microvascular endothelium and smooth muscle, may facilitate studies of human blood-brain barrier function as well as the pathogenesis of cerebral microangiopathies unique to the human brain.Funded by Canadian Heart Foundation, Heart and Stroke Foundation of Ontario and UCLA Biomedical Research Support Grant 相似文献
15.
Summary Two different aspects of tritiated thymidine (3H-Tdr) reutilisation in skeletal muscle were examined. Injection of a high dose (7 Ci/g) of 3H-Tdr into mice prior to crush injury of skeletal muscle resulted in heavy labelling (grain counts) of myotube nuclei 9 d later. In contrast, myotube nuclei were essentially unlabelled when a low dose (1 Ci/g) of 3H-Tdr was injected at similar times with respect to injury. It was concluded that labelling seen after the high dose was due to reutilisation of 3H-Tdr. (Such 3H-Tdr reutilisation can account for the results of Sloper et al. (1970) which previously supported the concept of a circulating muscle precursor cell.) When replicating muscle precursors were labelled directly with 3H-Tdr 48 h after injury, the percentages of labelled myotube nuclei and the distribution of nuclear grain counts were similar with either high or low dose.We also investigated whether the light labelling seen in regenerated myotube nuclei after 9 d, when 3H-Tdr had been injected before the onset of myogenesis (as found by McGeachie and Grounds 1987), was due to 3H-Tdr reutilisation or, alternatively, to proliferation of local cells in the wound which subsequently gave rise to muscle precursors. Labelling of myotube nuclei was compared in mice injected with 3H-Tdr either 2 h before, or 2 h after injury. In another experiment, mice were injected 12 h after injury and lesions sampled 1, 12 or 36 h later, to see whether local cells were replicating 12 h after injury, and what labelled cells subsequently entered to wound. No difference was found in myotube labelling between mice injected before or after injury, and no cells replicating locally in the wound at 12 h after injury were observed. The results clearly show that the light labelling was due to 3H-Tdr reutilisation. 相似文献
16.
Summary In the present study lectin-binding sites were investigated for the lectins Ricinus communis agglutinin (RCA I), wheat germ agglutinin (WGA), soya bean agglutinin (SBA), concanavalin A (Con A), Lotus tetragonolobus(LTA) and Limulus polyphemus agglutinin (LPA) during the initial stages of vasculogenesis of the CNS-anlage in 10 to 12-day-old NMRI mouse embryos. Specific binding sites for the lectins RCA I (sugar specificity: -D-galactose, N-acetylgalactosamine), WGA (sugar specificity: N-acetylglucosamine, sialic acid), and SBA (sugar specificity: N-acetylgalactosamine, -D-galactose) were detected in the newly formed capillaries within the neuroepithelial cell layer. In contrast, binding sites for Con A, LTA and LPA could not be observed at the start of the vascularization of the CNS-anlage. From these results, the conclusion can be drawn that glycoconjugates containing D-galactose, N-acetylgalactosamine and N-acetyl-glucosamine moieties are involved in the early vasculogenesis of the embryonic CNS-anlage of the mouse. 相似文献
17.
Summary Pre-implantation-stage embryos from rats, mice, and guinea-pigs were transferred to a non-uterine site — the anterior chamber of the eye — of female recipients. All 9 combinations of transfers were performed: 3 allogeneic (intraspecies) transfers as controls, and 6 xenogeneic (interspecies) transfers. Implantation, as judged by extravasation from blood vessels of the iris or ciliary body occurred with success rates of 90.4% per transfer in the control rat group, 76.9% in the control mouse group, and 81.8% in the control guinea-pig group. Significantly reduced implantation rates occurred in the rat to guinea-pig (0%), mouse to rat (46.9%), mouse to guinea-pig (6.7%), and guinea-pig to rat (0%) groups compared to controls. Reductions, although not significant, also occurred in the other 2 groups: rat to mouse (77.8%), and guinea-pig to mouse (44.4%). These results together with some ultrastructural and lightmicroscopical observations suggest a degree of species specificity involved in the vascular response to the implanting embryo. We propose that the peri-implantation embryo produces a signal(s) which is to some extent species specific and which in the normal allogeneic situation is responsible for the early vascular effects seen at implantation in most eutherian mammals. 相似文献
18.
Giuseppe Familiari M.D. Stefania A. Nottola Antonio Familiari Pietro M. Motta 《Cell and tissue research》1989,257(2):247-253
Summary The present study provides further details on the fine-structural three-dimensional architecture of the zona pellucida (ZP) in growing and atretic follicles of mice by use of ruthenium red in combination with the detergents Triton X100 and saponin. These detergents were used for extraction of the soluble fraction of the zonal proteins in an attempt to expose the structural zonal glycoproteins, which in turn can be viewed as minute three-dimensional networks upon transmission- and scanning electron-microscopic examination. By use of these methods, the ZP of growing follicles appeared to be formed by interconnected filaments which also bind to globular structures building up a three-dimensional lattice. In contrast, the ZP of stage I as well as other (II and III) stages of atretic follicles showed a structure characterized by the presence of closely packed granules connected with short filaments to form a close-mesh reticulum. This structural change of the ZP, which in the present study is also associated with the disappearance of gap junctions within the granulosa and cumulus cell population, might represent one of the early events involved in the onset of atresia. These changes, most probably depending on an altered secretory activity of both oocytes and follicle cells, might lead to a degradation of the ZP network structure and to its subsequent increased density (condensation). All these morphodynamic events eventually contribute to a sequestration of the oocyte in the early stage of atresia. 相似文献
19.
Dr. Shigeru Sakiyama Yohko Nakamura Katsuo Tokunaga Hiroshi Takazawa Yoshinori Ohwaki Toshio Nagano 《Cell and tissue research》1989,258(2):225-231
Summary In-situ hybridization experiments have been performed using isoactin ( and )-specific riboprobes in various tissues of the rat and mouse. Distribution of the grains of actin mRNAs for both and types was similar throughout sections of the rat testis. Although both mRNAs were evenly distributed in the seminiferous tubule, extremely heavy labeling was observed in about 10% of the seminiferous tubules that could be identified as stage XII of spermatogenesis. At high magnification, grains of the mRNA were found in the cytoplasm of elongating spermatids and in the Sertoli cell cytoplasm at the adluminal side. Much higher density of the grains of mRNA was observed in the neck region of the spermatids at stage XII. Thus, the dense distribution of cytoskeletal actin mRNAs is stage-specific in the tubule during spermatogenesis in the rat. The high expression of both and actin mRNAs was also observed in the epithelial cells of the intestinal crypts. 相似文献
20.
Previous studies have shown the existence of an autonomous mitochondrial GDPmannose: dolichylmonophosphate mannosyltransferase, located in mitochondiral outer membrane of liver cells. As nothing is known about glycosylation sites in mitochondria, we have investigated the topological orientation of this enzyme in intact mitochondria, using controlled proteolysis with trypsin. Mitochondria were purified sequentially by mild ultrasonic treatment and sucrose density gradient. Purity and homogeneity of mitochondrial fraction were assessed by electron microscopy and specific marker enzymes measures. Our data provide evidence for a mitochondrial GDPmannose: dolichylmonophosphate mannosyltransferase facing the cytoplasmic side of the outer membrane. However, the exposure of this enzyme to the water phase has been shown to be dependent on the ionic strength of the environment. 相似文献