ISSN:0003-276X    

DOI:10.1002/ar.1092370416

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe three‐dimensional configuration of the Golgi apparatus has been examined with the electron microscope in thick Golgi sections ofSaccharomyces cerevisiaeprepared from a wild‐type strainandfrom sec7 mutants maintained for various periods of time at the nonpermissive temperature of 37°C and then returned to the permissive temperature of 24°C. Reduced osmium postfixation of glutaraldehyde fixed specimens stained intensely the content of Golgi elements and thus facilitated their three‐dimensional characterization. In wild‐typeS. cerevisiae, the Golgi elements usually appeared as isolated networks of membranous tubules dispersed throughout the cytoplasm. Along such networks, distensions filled with stained material were similar in size to nearby secretory granules, suggesting that the latter formed by fragmentation of the Golgi elements. Insec7mutants maintained at 37°C in low (0.1%) glucose medium, secretion granules progressively decreased in number and soon disappeared. Concomitantly the networks of Golgi tubules increased in size and complexity, lost their distensions, and then transformed into flattened sacules forming stacks of up to seven or eight saccules that were similar to the Golgi stacks seen in mammalian cells. However in contrast to the latter, connections between the saccules were evident and Golgi‐associated small vesicles were generally absent. Following return to the permissive temperature (24°C), secretion granules reappeared, the Golgi stacks progressively decreased in size, and resumed their initial state of separated small tubular networks. Thus insec7mutant, grown at 37°C in low glucose medium, segregation of secretory granules is blocked. As a result, Golgi membranes accumulate to form a continuous system of stacked and interconnected saccules. © 1993

ISSN:0003-276X    

DOI:10.1002/ar.1092370402

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe distribution of the 25 kDa heat shock protein (hsp 25) in a number of tissue types from unstressed rats was investigated. Immunohistochemical analysis showed that hsp 25 was not found in the thymus, brain (cerebral cortex and cerebellum), testis, adrenal, liver, spleen, or kidney. A number of cells in the anterior pituitary showed strong staining. These cells were tentatively identified as being either gonadotropes or thyrotropes. Strong staining was also observed in the blood vessels within these tissues. Hsp 25 was found to be localised predominantly to intestinal smooth muscle of the duodenum and colon and to vascular smooth muscle. Smooth muscle from other sites, such as the trachea, was also intensely stained. Lower and more variable amounts of staining were observed in cardiac and skeletal muscle. These observations suggest that hsp 25 is associated with cytoskeletal elements in muscle, and that the high staining intensity in smooth muscle might be due to the lack of internal architecture present in this muscle type. © 1993 Wiley‐Liss, I

ISSN:0003-276X    

DOI:10.1002/ar.1092370403

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

年代:1993

数据来源: WILEY

摘要:

AbstractTooth drift requires the deformation of the root socket and the adjustment of the other components of the attachment apparatus, namely, the periodontal ligament (PDL) and the cementum. Indomethacin (7.5 mg/kg/d), an inhibitor of prostanoid synthesis, provoked in rats a depression in the bone resorption effecting the deformation of the socket (Lasfargues and Saffar, Anat. Rec.,234:310–316, 1992). In the present paper we examined the consequence of this treatment both on the PDL and the root surface. After 3 days of treatment, when osteoclastic resorption was not yet disturbed, the root had been markedly resorbed (P<0.05) opposite the resorbing bone surface; at that time the PDL width remained in the normal range. After 7 days, i.e., when the bone resorption was depressed, the PDL was widened as the result of the ongoing root resorption. Despite the extensive root resorption, the anchorage of the PDL fibers appeared to remain effective, suggesting that it was rapidly restored. On day 14 at the time of the bone resorption recovery, cementum was deposited in the root resorption lacunae and the PDL width had returned to its control value. As early as day 3 the daily rate of dentine formation increased in the pulp area subjacent to the root resorption lacunae (P<0.01). These data demonstrate that (i) the responses of the different components of the periodontal apparatus are coordinated to allow for the maintainance of the PDL width so that when bone resorption is disturbed, root resorption compensates for it, and (ii) the odontoclasts can differentiate and resorb under prostanoid inhibition whilst osteoclastic resorption of the bone socket is inhibited. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092370404

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis study was undertaken to determine the composition and morphology of lipid droplets in situ and isolated from oviductal epithelial cells and oviductal fluid. Oviductal epithelial cells were harvested enzymatically from oviducts of cows in either the luteal or the follicular stages of the ovarian cycle. Lipid droplets were isolated from cellular homogenates and characterized biochemically using thin layer chromatography. The morphology of lipid droplets in oviductal epithelial cells and in fractions isolated by ultracentrifugation from cellular homogenates was examined by electron microscopy. Lipid droplets isolated from oviduct epithelial cells varied in composition with the ovarian cycle and the oviductal region. There was more total lipid in droplets isolated from cows in the luteal than follicular phase of the ovarian cycle. Most of this difference was due to large amounts of esterified cholesterol present in the samples from luteal‐stage animals. The most esterified cholesterol was found in droplets isolated from the oviductal isthmus of luteal cows. Droplets similar in lipid composition to those isolated from epithelial cells were found in oviductal fluid. Four distinct types of lipid inclusions were evident in electron micrographs of oviductal epithelia and characterized as osmiophilic droplets, lipofuscin‐like clusters, lamellar structures, and composite bodies. All of the lipid inclusions were found in droplet isolates except for the extracted lipid portion of the composite body. The presence and diversity of oviduct epithelial lipid inclusions suggest that the oviductal epithelium may be very active in lipid metabolism, particularly cholesterol dynamics. © 1993 Wiley‐Lis

ISSN:0003-276X    

DOI:10.1002/ar.1092370405

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

年代:1993

数据来源: WILEY

摘要:

AbstractMeasurements of extremely high osmolalities in cauda epididymidal fluids of hibernating bat species led to an investigation of the junctional complex morphology of the epithelium of this sperm storage site. Freeze fracture replicas revealed the presence, at certain times of the year, of a tight junction architecture that resembled that traditionally thought to be exclusive to the blood‐testis barrier, the strongest permeability barrier in the body. It is hypothesized that seasonal establishment of these specialized Sertoli cell‐like tight junctions is necessary to the maintenance of the high osmotic state of the luminal environment, allowing for the prevention of dilution of its contents by paracellular routes and its protection from bursting under the osmotic pressure contained within. © 1993 Wiley‐Lis

ISSN:0003-276X    

DOI:10.1002/ar.1092370406

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

年代:1993

数据来源: WILEY

摘要:

AbstractImmunoelectron microscopic localization of endothelin (ET) using the mouse monoclonal anti‐ET sera was performed on the pre‐and postnatal rabbit umbilical vein during stages when Weibel‐Palade (WP) bodies increase in number in the endothelial cells.The immunoreactions are localized in the rough endoplasmic reticulum, Golgi cisterns, and WP bodies that are actively segregated from the Golgi apparatus. After degranulation and extracellular release of WP bodies was induced by compound 48/80, heavy immunoreactions were seen in both vascular lumen and cytoplasm near the degranulated WP bodies. These results indicate that ET is stored in WP bodies after segregation from the Golgi apparatus and released from the endothelial cells concomitantly with other components of these granules by exocytosis.Because the immunoreactions are also seen in pinocytotic vesicles that are occasionally in contact with WP bodies, it seems likely that WP bodies are also involved in the uptake and storage of ET from blood plasma. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092370407

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

年代:1993

数据来源: WILEY

摘要:

AbstractAlthough there is a recent increase in the use of the isolated pancreatic islets of the rat in the transplantation and functional studies, there has been no detailed quantitative assessment on the size and cellular constituents of islets after the isolation procedure. The present work was undertaken to study the size classes of the isolated islets and the morphometry of their cellular populations.Islets of the rat pancreas were isolated by using the intraductal collagenase digestion technique, the most commonly used procedure for the isolation of pancreatic islets. Different endocrine cells of the isolated islets were stained by immunoperoxidase staining techniques. The distribution of the cellular constituents of the isolated islets was similar to that of the intact islets of the normal pancreas; A, D, and PP cells were peripherally arranged around the centrally located B cells. However, morphometric quantitative study showed that the percent volume and percent number of A, D, and PP cells of the isolated islets were lower than those of the corresponding intact ones. Further, the mean true diameter of the isolated islets was lower than that of the intact ones. These data indicate loss of islet cells during the process of isolation. Most of the lost cells were from the periphery of islets. This may provide an explanation for the incomplete metabolic control and recurrence of hyperglycemia encountered after isolated islet transplantation in the treatment of diabetes mellitus. It seems that further refinements of the isolation techniques are necessary to obtain islet tissue with total cellular integrity, before a complete success in transplantation could be achieved. © 1993 Wiley‐Liss, I

ISSN:0003-276X    

DOI:10.1002/ar.1092370408

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

年代:1993

数据来源: WILEY

摘要:

AbstractLaboratories engaged in secretory studies of rat pancreatic islets often encounter high baseline insulin secretion with poor secretory response to secretagogues, such as glucose. The specific morphologic abnormalities that accompany this unregulated release have not been described. We isolated islets comparing two approaches. Both used stationary digestion with collagenase. In method I, we distended the biliary duct extracorporeally with collagenase and minced the pancreas after a 28 min digestion (37°C). In method II, we distended the pancreas intracorporeally and digested for 40 min without mincing. Both methods utilized a similar collagenase concentration (2 μg/ml in Hank's balanced salt solution (HBSS)). Both methods yielded over 300 islets/rat. Islets from both methods appeared intact, when viewed under the dissecting microscope. We found that adequate secretion from incubated islets was evoked with method I, i.e., low basal insulin levels at low glucose (3.3 mM), tripling at 11.0 mM glucose, and nearly quadrupling in response to higher glucose (16.7 mM). In contrast, method II was characterized by high basal levels without response to higher glucose. Ultramicroscopic examination of islet B cells in method I revealed normal cytological features, while B cells in method II showed marked degranulation, profiles of swollen endoplasmic reticulum, and swollen mitochondria. Morphometric analysis of B cells confirmed quantitatively a decrease in secretory granule density and mitochondrial enlargement in method II compared to method I. Anatomic changes, largely confined to the B cells of islets may account for functional alterations of responses. Defects cannot be predicted from gross appearance of islets. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092370409

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

年代:1993

数据来源: WILEY

摘要:

AbstractA combination of light and electron microscopy techniques was applied to characterize a luteinizing hormone (LH)‐gonadotroph‐like cell in the anterior pituitary gland of the adult domestic chicken. This cell type (mean ± sem, 91 ± 8 μm2) was larger than typical LH‐gonadotrophs (71 ± 5 μm2,P<0.01) and seen in pituitary glands from adult males but not those from adult females of the same age. The ultrastructural features of these cells were similar to typical LH‐gnoadotrophs in the same section, except for the presence of large (1,126 ± 77 nm diameter), round, or polymorphic electron‐dense inclusions (14 ± 3 per cell) in the cisternae of the endoplasmic reticulum. When resin sections of anterior pituitary gland were stained with the vapours from the fixative osmium tetroxide and a solution of potassium ferricyanide, inclusions were found that appeared to be lipid in nature and were circumscribed by the cisternal membranes of the endoplasmic reticulum. These lipid inclusions were associated occasionally with acid phosphatase and lysosome‐like bodies. The cellular pigment, lipofuscin, considered to be a marker of aging, was absent from the anterior pituitary glands from these adult chickens. These observations suggest that the appearance of lipid in LH‐gonadotrophs is unlikely to be age‐related and an alternative explanation is discussed in relation to a sex difference in the LH response of adult chickens to gonadotrophin‐releasing hormone (GnRH)

ISSN:0003-276X    

DOI:10.1002/ar.1092370410

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

年代:1993

数据来源: WILEY