摘要:

Summary—This study was performed to clarify the fate of membrane constituents internalized from the apical domain in secretory cells, in particular their possible recycling and the compartments involved in it. Glycoproteins of the apical membrane of seminal vesicle secretory cells from guinea‐pig were covalently labeledin vitro(0°C, 20 min) with3H‐galactose and the epithelium incubated for 15 min (37°C, first incubation) to allow endocytosis. The label which was not internalized was then exposed to enzymatic hydrolysis (0°C, 30 min) and the epithelium re‐incubated to allow membrane movement for 15 and 30 min (37°C, 2nd incubation). After each step of the protocol, tissue pieces were fixed and processed for electron microscope autoradiography and the results studied by morphometric analysis. Following labeling, 99% of the silver grains were associated with the apical domain of the cell membrane (AD). After the 1st incubation at 37°C, 30° of the grains were inside the cells in association with the cytoplasmic vesicles (Cyt ves), secretory vacuoles (SV), Golgi vesicles (GV), Golgi cisternae (GC), multivesicular bodies (MVB), lysosomes (LYS), and the cell membrane basolateral domain (BLD). About 58% of non‐internalized radioactivity was removed by hydrolysis. During the 2nd incubation at 37°C the concentration of label increased in BLD and LYS, decreased in SV and MVB, and fluctuated in GC, GV and AD. The distribution of grains observed at 15 min, as compared using the χ‐square test, was highly significantly different from that expected without recycling. The results show that cell membrane glycoproteins internalized at the cell apex recycle back to the membrane apical domain and are consistent with the involvement of GC and SV in the recycling pathway. Membrane shuttle between the apical and basolateral domains of the cell membrane is also suggested by

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90307-O

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Endocytosis was studied in the seminal vesicle secretory cells of castrated and control hamsters in order to investigate the effect of testosterone withdrawal in the endocytic activity of these cells. Horseradish peroxidase was injected into the glands lumen after removal of their contents, and tracer distribution was qualitatively studied, and the number of labeled endocytic vesicles quantitatively analyzed, following 5, 20, 40 and 60 min incubation. The following compartments are labeled both in castrate and control cells: 1), endocytic vesicles; 2), vacuoles with or without secretory material; 3), multivesicular bodies; 4), Golgi cisternae; 5), intercellular spaces; 6), sub‐epithelial space. The pattern of labeling is lighter in castrate than in control cells and the labeling of Golgi cisternae, which correlates with a significant peak in the number of endocytic vesicles, is observed later in castrated animals than in controls: 40 min vs 20 min. Exocytosis, as evaluated through the fraction of secretory protein releasedin vitro, decreases following castration. Endocytosis performed in castrated, pilocarpine treated animals shows that the Golgi labeling, coinciding with numerous labeled endocytic vesicles, is advanced from 40 to 20 min after stimulation of exocytosis. The results show that, in the seminal vesicle secretory cells a) the endocytic pathway does not depend on testosterone; b) testosterone withdrawal decreases endocytosis and delays the kinetics of labeling and; c) endocytosis couples to exocytosis, probably so regulating the apical cell membrane a

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90308-P

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The ovine embryo produces an interferon named ovine Trophoblastin (oTP) which is involved in the maternal recognition of pregnancy and ensures the maintenance of progesterone secretion by thecorpus luteum. We have used indirect immunohistofluorescence andin situhybridization on histological sections to investigate the fate of this protein and its mRNA in ovine embryos from days 3 to 25 of pregnancy. The level of expression was measured by image analysis of the autoradiographs afterin situhybridization. Both techniques clearly demonstrated that oTP and its mRNA were specifically localized in the extra‐embryonic trophoblast. Neither the embryonic cells, nor the yolk sac or the amniotic tissues produced the protein or its mRNA. The protein could be detected by d 11 of pregnancy in the elongated blastocyst. Maximum of expression is observed at d 14 and the level decreased by d 16 of pregnancy. The arrest of expression occurred in the regions of trophoblast which have established cellular contacts with the uterine epithelium during the implantation proc

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90309-Q

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Using our improved method for culturing 11‐day mouse forelimb budsin vitro, we have investigated the effects of a local application of all‐trans‐retinoic acid (RA) on growth, cartilaginous differentiation and skeletal patterning in the mammalian limb bud. Carrier implants of catgut impregnated with DMSO or various doses of RA in DMSO were inserted at the apex of the buds in the proximo‐distal axis just beneath the apical ectodermal ridge. After 6 days of culture, cartilaginous skeletons were stained and explants were processed for morphological analysis and quantitative study using computerized optical image analysis. Buds treated with low doses of RA exhibited stimulated growth and chondrogenesis. Moreover, hypertrophied and fused metacarpals were seen within explants treated with the lowest dose. High doses strongly inhibited growth and skeletal morphogenesis. An intermediate dose sustained cartilaginous differentiation at the same level as low doses, but concomitantly disturbed the skeletal pattern. These results are discussed considering reported RA effects on other experimental systems including avian limb bud as anin vivomodel or cell cultures as anin vitrosimplif

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90310-Y

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Rat spinal cord cells were cultured on cryostat sections of innervated and denervated muscle. Neurite outgrowth was greater on sections of denervated muscle, which therefore appeared to act onin vivonerve regeneration. It seems that muscle sections were able to release into the culture medium factors that increase proliferation of fibroblasts. The muscle therefore appeared able to modulate its interaction with its environment by acting on different types of cell

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90311-P

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The cellular immortalization activity of cloned genes can be identified either in a colony‐forming assa of transferred primary rat embryo fibroblasts or in a co‐operation assay together withras. However the demonstration of immortalization activities carried by cellular genes has not been reported. Here we establish that SV40 early genes integrated in genomic DNAs can be stably transferred into rat embryo fibroblasts and selectedviatheir immortalization activity. Attempts to extend this assay to the identification of dominant genes putatively involved in the immortality of several other immortal post‐crisis or tumor cells have been unsuccessful suggesting that the immortal phenotype can be brought about through different p

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90312-Q

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Image analysis was used to study the repair process of a circular mechanical lesion of confluent human endothelial cells in culture after irradiation (10 Gy) prior to wounding. Coverage of denuded areas 48 and 96 h after injury of endothelial cells was identical in control and irradiated cultures, although the labeling index was lowered by 80 to 95% in irradiated cultures. The cell density of non damaged irradiated areas was decreased by 50%. When cultures were submitted to increasing doses of radiation (5.0–30 Gy), the labeling index of the cells diminished rapidly between 0 and 5.0 Gy and reached a plateau at 10 Gy. The decrease in cell density (50% of control at 96 h) was identical at each dose of radiation. Thus cell migration alone could be sufficient for the repair of the lesion, while cell proliferation would mainly maintain the original cell density. The addition of heparin to the culture medium slowed down cell migration and proliferation, but the speed of repair was identical in irradiated and non‐irradiated cultures. Acidic fibroblast growth factor plus heparin accelerated equally the repair process whether the cultures were irradiated or not. In irradiated cultures the presence of acidic fibroblast growth factor and heparin maintained cell density in confluent areas at a level similar to that in non‐irradiated damaged control cultures without addition of mitogens. Thus heparin and acidic fibroblast growth factor play a role in cell proliferation, in the maintenance of the cell monolayer integrity and in restoring a continuous layer by rapid cell migration and elongation after irra

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90313-R

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The distribution of lysozyme in the different secretory granules (SG) of human tracheal and bronchial submucosal gland serous cells was studied by light and electron microscopy, using a post‐embedding immunogold technique. SG were differentiated into 5 phenotypes according to their structure and staining electron density. All the SG‐phenotypes were reactive to lysozyme. In the heterogeneous SG‐phenotypes, quantitative immunocytochemistry showed that the density of lysozyme labeling was significantly higher in the electron‐dense central core compared to the electron‐lucent peripheral rim. At the tracheal level, the density of lysozyme did not vary significantly within the different SG‐phenotypes, whereas at the bronchial level, the differences were significant. Moreover, the lysozyme labeling density was much higher in the bronchial than in th

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90314-S

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—An ultrastructural and immunocytological study was carried out on the collar cells of the optic tentacle ofHelix aspersa. These cells are supposed to be the source of a reproduction controlling hormone. The immunocytological study was performed using an anti‐methionine enkephalin antibody obtained from rabbits in our laboratory. The collar cells are characterized by an enlarged rough endoplasmic reticulum, numerous mitochondria and Golgi bodies surrounded by secretory vesicles, suggesting an intense synthesizing activity. Their principal feature consists of numerous various‐sized granules where methionine enkephalin immunoreactivity is localized. No classical neurosecretory granules are observed while synapse‐like structures are often encountered. The cells should not be regarded as neurosecretory cells but rather as glandular cells which could ensure different functions, one in relation to reproduction, and another in relation to perception processes, particularly as they contain methionine enkephalin‐like

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90315-T

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Using thin‐sectioning for electron microscopy, including the careful examination of a long series of sections which contained several complete cells, we describe the form of the contents of the unusually enlarged distal periplasmic space in the epidermis of the seeds ofCydonia oblonga. The major feature is a large stack of cellulosic material arranged helicoidally, which previous work has indicated is fluid and similar to a cholesteric liquid crystal. This stack has a serrated margin, which is interpreted as indicating a surface shaped like that of a screw or a concertina. The overall shape based upon artistic reconstructions from serial sect?? shows great ?? variability, due in part to the limits set by the enclosing cell walls. This together with observations of variation in helicoidal pitch and of helicoidal arc reversal, indicates that the crystals are highly plastic in form. It is suggested that the form is determined by a combination of intrinsic and extrinsic factors. Not all microfibrils in the periplasmic pocket are arranged helicoidally, and it is argued that the coexistence of helicoidal and non helicoidal microfibrillar arrays indicates that a gradient of an agent which controls cellulose microfibrillar architecture is present. This may indicate that cell wall architecture can similarly be determined by subtle regulation of agents which control helicoidal pi

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90316-U

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY