摘要:

AbstractFour monoclonal antibodies were raised against crude gap junction fractions of rat liver to clarify the distribution of gap junctions during animal development and to analyze gap junction expression in vivo and the polarity of hepatocytes in vitro. Among the monoclonal antibodies obtained, HAM8 antibody recognized the 27‐kDa rat liver gap junction protein connexin 32. This antibody recognized gap junctions at the contiguous faces of hepatocytes, and the antigen was also observed in exocrine pancreas and salivary gland but not in kidney, heart, esophagus, or thymus. HAM8 did not react with amphibian or fish liver, heart, esophagus, stomach, or intestine as assessed via the immunofluorescence method on frozen sections. A few hepatocytes and many hemopoietic cells were seen in rat fetal liver at 15 days of gestation. HAM8 antigen was expressed on some hepatocytes but not on any hemopoietic cells. As the fetus grew, the number of hepatocytes in the liver increased gradually, together with the amount of HAM8 antigen. The distribution of HAM8 antigen at 25 days after birth was similar to that in adult liver. When the expression of HAM8 antigen was examined in primary cultured hepatocytes using the immunofluorescence method, the antigen was observed clearly between the hepatocytes. However, most of the HAM8 antigen on the free surface of hepatocytes disappeared within 4 hr. HAM8 antigen was not expressed on AH7974 rat hepatoma cells when they formed small islets in the rat peritoneal cavity or within the liver. When HAM8 IgG antibody was injected intravenously, the HAM8 signal was expressed in the liver. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092350302

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe lipid‐secreting cells of the Harderian gland of the Syrian hamster were studied using light, transmission, and scanning electron microscopy. Three morphologically different secretory cell types are identified in the gland: type I and II cells of the male gland and, distinct from either, the female gland cell. In all secretory cell types, lipid droplets in the cytoplasm were surrounded by unit membranes. Ultrastructural evidence of the involvement of the Golgi apparatus in the formation of the secretory vacuoles was obtained. The process of secretion involved the fusion of the boundary unit membrane of the vacuole with the plasma membrane and the release of the vacuolar content alone into the lumen. No evidence of holocrine processes was observed in this study. In addition to lipids, vacuoles contained materials whose solubility properties clearly differed from those of lipids. There appear to be variations in the ultrastructural characteristics of the vacuole content of the different types of secretory cell. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092350303

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe three‐dimensional structure of the Golgi apparatus and its compartments in prolactin cells has been examined in lactating rats in which secretion of prolactin was suppressed by removing the litter or stimulated by allowing the pups to suckle again. As soon as 2 hr after removal of the litter, large irregular progranules and numerous large pale vesicles accumulated in the trans‐Golgi area together with vesicular or tubular fragments. The cis‐tubular network was no longer recognizable on the cis‐face of the Golgi ribbon; the saccules of the midcompartment were partitined by narrow fissures and also became perforated in register by numerous fenestrations of various sizes and irregular contours. The concomitant appearance of numerous vesicles in the cavities thus formed as well as in the surrounding cytoplasm indicated that they probably arose by the progressive cavitation and fragmentation of saccules of the mid compartment. Such a process, which reached a maximum between 4 and 6 hr after removal of the litter from the mother, was no longer observed at 8 and 12 hr, at which time intervals the Golgi apparatus was reduced in size with no cis‐tubular elements and progranules on its trans‐aspect and few vesicles in its surroundings. When mothers, separated from their litters for a period of 12 hr, were returned to their pups for 20 min, the cis‐tubular network reappeared on the cis‐aspect of the Golgi stacks and presumably formed by fusion of vesicles and anastomosed tubules located next to the cisternae of the rough endoplasmic reticulum. In addition, the structure of the midsaccules returned to the stimulated condition, and early progranules were again segregated within the trans‐most saccules of the Golgi stack. Hence, the Golgi apparatus of prolactin cells was rapidly and deeply modified in the presence or absence of stimulation. © 19

ISSN:0003-276X    

DOI:10.1002/ar.1092350304

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

年代:1993

数据来源: WILEY

摘要:

AbstractLactating mammary glands fixed by perfusion with 5% glutaraldehyde subsequently were postfixed with potassium ferrocyanide reduced osmium or were treated with tannic acid. Stained thin sections were examined with the electron microscope and stereopairs were prepared. The distribution of casein submicelles was analyzed in the various components of the Golgi apparatus. The Golgi stacks were composed of five or six elements, all of which contained casein submicelles 20 nm in diameter. The cis‐tubular network or cis‐element, as well as the underlying three or four midsaccules, showed these casein submicelles either attached to their membrane or free in the lumen. The trans‐most element of the stacks formed distended prosecretory granules in which both isolated or clustered casein submicelles were suspended in an electron‐lucent fluid. These micellar aggregates increased in size and became progressively more compact to form spherical dense bodies or casein micelles, in which the individual 20 nm particles could easily be resolved. Casein micelles were seen in secretory granules in addition to a wispy material of low density. The numerous small spherical vesicles (80 nm or larger) seen on the cis, lateral, or trans aspects of the stacks did not appear to contain free casein submicelles. This raises questions regarding the role of these vesicles in the transport of casein macromolecules through the Golgi stacks. It was noticeable that in this Golgi apparatus a trans‐Golgi network was limited to a few small residual tubules free from casein submicelles. It thus appears that the greater part of the trans‐most Golgi element gives rise to the large prosecretory granules. After leaving the Golgi region and prior to exocytosis, the secretory granules often fuse to form larger granules before exocytosis. © 1993 Wil

ISSN:0003-276X    

DOI:10.1002/ar.1092350305

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of low‐energy laser (He‐Ne) irradiation on the process of skeletal muscle regeneration after cold injury to the gastrocnemius muscle of the toad (Bufo viridis) was studied using quantitative histological and morphometric methods. The injured zones in the experimental toads were subjected to five direct He‐Ne laser (632.8 nm wavelength) irradiations (6.0 mW for 2.3 min) every alternate day starting on the fourth day postinjury. Muscles that were injured as above, and subjected to redlight irradiation, served as a control group. Morphometric analysis was performed on histological sections of injured areas at 9, 14, and 30 days postinjury. At 9 days postinjury, mononucleated cells populated 69.3% ± 16.8% of the total area of injury. Thereafter, their volume fraction (percent of total injured zone) decreased gradually but more rapidly in the laserirradiated muscle than in the control. The volume fraction of the myotubes in the laser‐irradiated muscles at 9 days of muscle regeneration was significantly higher (7.0% ± 2.2%) than in the control muscle (1.2% ± 0.4%). Young myofibers in the laser‐irradiated muscles populated 15.5% ± 7.9% and 65.0% ± 9.5% of the injured area at 9 and 14 days of muscle regeneration, respectively, while in control muscles these structures were not evident at 9 days and made up only 5.3% ± 2.9% of the traumatized area at 14 days postinjury. The volume fraction of the young myofibers further increased by 30 days of muscle regeneration making up 75.7% ± 13.2% of the traumatized area, while in the laser‐irradiated muscles most of the injured zone was filled with mature muscle fibers. It is concluded that He‐Ne laser irradiation during the regeneration process markedly promotes muscle maturation in the injured zone following cold injury to the toad gastrocnemius muscle. ©

ISSN:0003-276X    

DOI:10.1002/ar.1092350306

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe physiological cross‐sectional area (CSA) of a motor unit (MU), taken as the sum of fiber areas measured on a single section through the approximate midlength of the MU, has been compared with the physiological CSA more strictly defined as the sum of the maximal areas to be found anywhere along the length of each of the MU fibers. The CSA at intervals along the fiber length was measured in fibers selected from four glycogen‐depleted, isolated MUs in the cat tibialis anterior (TA), and profiles of the summed areas made. In one MU, measurements were also taken on all the MU's fibers at less frequent intervals. The profiles demonstrate that the summed CSA based on each fiber's maximum CSA may exceed that derived from observation on any single section by as much as 20%. As a consequence, values that have been reported for specific tension (force per unit area) of MUs in the TA and probably other muscles may have been overestimated, especially for those MUs of fast type. Estimates were also made of the share of the MU's total force transmitted directly to the tendons of origin and insertion via endings of the blunt musculotendinous type as distinct from tapering intrafascicular endings acting through in‐series connective tissue and non‐MU fibers. In two MUs of slow type in which most fibers ran from tendon to tendon, “partial tapering” extending over 1 cm of the fiber length accounted for a third of the total physiological CSA, and indicated yet another mode for relay of the MU's force to the tendon. © 1993 Wil

ISSN:0003-276X    

DOI:10.1002/ar.1092350307

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of estradiol and progesterone on the cytodifferentiation of epithelial cells in the oviduct of the newborn golden hamster were investigated by electron microscopy. Consecutive daily injections of estradiol‐17β (E2) induced various ultrastructural changes in undifferentiated epithelial cells of the neonatal oviduct. Ciliogenesis, formation of some ciliary buds, and ciliation were frequently observed in the oviductal epithelial cells on days 1–4 of consecutive treatments with E2. On days 2 and 3, the remaining cells contained well‐developed Golgi apparatus and rough endoplasmic reticulum. Thereafter, a few secretory granules were observed in the cytoplasm of these cells, indicative of differentiation into secretory cells. Occasionally, secretory cells undergoing ciliogenesis or mitosis were found in the epithelium. On day 9, many fully mature ciliated and secretory cells were observed. Quantitative studies clearly showed that E2induced the differentiation of both ciliated and secretory cells. By contrast, consecutive daily injections of progesterone significantly stimulated the appearance of ciliogenic and ciliated cells but not that of secretory cells. These results indicate that the induction of differentiation of secretory cells is a specific effect of estrogen, whereas the differentiation of ciliated cells may be closely related to effect of progesterone as well as of estrogen. It is suggested that hormonal effects on differentiation differ between ciliated and secretory cells in the oviductal epithelium of the newborn golden hamster. © 1993 Wiley‐

ISSN:0003-276X    

DOI:10.1002/ar.1092350308

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe luminal surfaces of epithelial cells in various regions of the bovine oviduct from cows, at the follicular and luteal phases of the estrous cycle, were examined by scanning electron microscopy. Marked cyclic changes were observed on the surface of the epithelium in the fimbriae and ampulla, but few changes were found in the isthmus and uterotubal junction. The epithelium of the fimbriae and ampulla of oviducts in the follicular phase were densely ciliated, and the cilia concealed the apical processes of the nonciliated cells. In the luteal phase, the nonciliated cells predominated in the epithelium and most of the ciliated cells were hidden by the bulbous processes of the nonciliated cells. The epithelium of the ampullar‐isthmic junction showed similar changes, but to a lesser extent. In the isthmus and at the utero‐tubal junction, the apical surfaces of the nonciliated cells were flat or gently rounded during the estrous cycle. Quantitative examinations by light microscopy showed that the mean percentage of ciliated cells significantly decreased in the fimbriae and ampulla at the luteal phase, but not in the other regions. The height of ciliated cells decreased dramatically in the fimbriae, ampulla, and ampullar‐isthmic junction at the luteal phase. By contrast, the height of nonciliated cells decreased significantly in the ampullar‐isthmic junction, isthmus, and utero‐tubal junction at the luteal phase, but not in the fimbriae and ampullae. The results demonstrate that there are regional variations and cellular differences in the cyclic changes associated with the oviductal epithelial cells in the cow. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092350309

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

年代:1993

数据来源: WILEY

摘要:

AbstractSertoli cell sulfated glycoprotein‐1 (SGP‐1) is a heavily glycosylated and sulfated 70 kDa protein that is secreted into the lumen of the seminiferous tubule where it binds to spermatozoa. Recent light and electron microscope immunocytochemistry has suggested that the testicular SGP‐1 detaches from the surface of spermatozoa in the lumen of the efferent ducts to be endocytosed within the endocytic apparatus of the epithelial nonciliated cells. The finding of SGP‐1 mRNA together with anti‐SGP‐1 immunogold labeling of the lysosomal compartment suggest that these cells synthesize an efferent duct form of SGP‐1. In the present study, a number of different experimental approaches (ligation, tunicamycin treatment and a combination of both) in combination with quantitative electron microscope immunogold labeling and Western blot analysis were performed in order to test this hypothesis. The number of gold particles and the profile area of the early (endosomes, pale multivesicular bodies) and late (dense multivesicular bodies, secondary lysosomes) endocytic apparatus were estimated in each of the experimental groups and expressed as the number of gold particles per μm2(labeling densities). The data revealed that ligation produced a significant reduction of anti‐SGP‐1 immunogold labeling of the early endocytic apparatus but not of the late endocytic apparatus. Tunicamycin treatment on the other hand produced a significant reduction of immunogold labeling of both the early and late endocytic apparatus. The combination of both treatments resulted in a more effective reduction of the labeling densities of these two endocytic compartments. These results thus indicate that the nonciliated cells of the efferent ducts are involved both in the endocytosis of the Sertoli‐derived SGP‐1 and in the synthesis of an efferent duct form of SGP‐1 that is targeted from the Golgi apparatus to secondary lysosomes after its glycosylation. In order to determine the biosynthetic pathway of SGP‐1 within the efferent ducts, an I. V. injection of35S‐cysteine followed by immunoprecipitation and SDS‐PAGE revealed that SGP‐1 was initially biosynthesized as a 55 kDa protein. This protein appears to be post‐translationally modified to a 65 kDa form after 1 hour, which preceded the appearance of the 70 kDa form, and smaller peptides of about 15 kDa characteristic of saposins after 3–4 hours. Western blot analysis of ligated efferent ducts showed an increase in the biosynthesis of the 70 kDa form of SGP‐1 when compared to untreated controls, however, it has yet to be established if this protein is secreted or retained in an intracellular compartment. These results thus further substantiate our hypothesis on the endocytosis of the Sertoli‐derived SGP‐1 by the nonciliated cells and the synthesis of an efferent duct form of SGP‐1 as well as provide evidence for the presence of 15 kDa saposins and its 65 kDa precursor in secondary lyso

ISSN:0003-276X    

DOI:10.1002/ar.1092350310

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis study compares the ultrastructure of beating canine hearts with that of hearts subjected to different clinically common forms of cardiac arrest. The contraction state per test field was ascertained according to a specially developed classification. The volume density of myofibrils and the surface to volume ratio of mitochondria were used as parameters for cellular and mitochondrial swelling. Contraction bands were not found in any of the differently pretreated hearts. Following immersion fixation, contractions as well as over‐ and hypercontractions in beating, fibrillating, and St. Thomas‐arrested hearts are significantly more pronounced than in HTK‐arrested hearts. Cellular and mitochondrial volumes were similar in beating and fibrillating hearts. St. Thomas‐perfusion significantly decreased cellular and mitochondrial volume compared to beating hearts, but these values were in the same range as in fibrillating hearts. Only HTK‐solution actually led to a strong reduction of these compartments. Compared to immersion, perfusion fixation after coronary perfusion with cardioplegic solutions led to comparable cellular volumes, but significantly elevated the percentage of relaxed sarcomeres and significantly reduced mitochondrial swelling. The best structural preservation of myocytes was found after HTK‐perfusion and perfusion fixation. Such ultrastructural quantitative and morphometrical parameters are powerful tools since results confirm that the degree of myocardial preservation depends on the method of cardiac arrest. This forms the basis for the choice of preconditions for subsequent ischemia. Furthermore, significant alterations of myocardial ultrastructure depend on a combination of the functional state of the heart, the method of cardioplegia, and the technique of fixation. © 1993 Wil

ISSN:0003-276X    

DOI:10.1002/ar.1092350311

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

年代:1993

数据来源: WILEY