摘要:

AbstractA morphological evaluation of intercellular bridges was undertaken during rat spermatogenesis. The dimensions and relationships of the bridges were shown to vary during different phases of spermatogenesis. Cellular divisions of spermatogonia and spermatocytes resulted in the partitioning of pre‐existing bridges by complex structures termedbridge partitioning complexes, which are described in detail, as is the process whereby new bridges are formed. The structure of premeiotic bridges was generally consistent; however, during spermiogenesis, the structure of bridges and bridge contents were modified at specific phases of their development. The plasmas membrane density associated with the cytoplasmic aspect of early step 1 spermatids separated into multiple dense bands that encircled the peripheral aspect of late step 1 spermatid bridges. By step 2 of spermiogenesis, these dense bands became associated with several cisternae of endoplasmic reticulum, which later coalesced into a single saccule that completely encircled the bridge structure by step 4. At steps 10–12 nm in diameter appeared within the bridge channel. At step 17 of spermiogenesis, the filament‐bounded densities were no longer apparent, but an anastomosing network of endoplasmic reticulum, often in the configuration of a sphere, occupied the entire central region of the bridge. In step 19 spermatids, the smooth endoplasmic reticulum within the bridge channel and the multiple cisternae lining the bridge density were gradually lost its prominence. Some cytoplasmic lobes were connected by extremely narrow (∼ 22 nm) cytoplasmic channels. Similar appearing channels were seen on the surface zone of cytoplasmic lobes or residual bodies, this observation suggesting that channels were sites of severence of bridges. Just prior to the separation or disengagement of the spermatid from the cytoplasmic lobe, selected bridges appeared to open to form large masses. After spermiation, residual bodies were not found joined by bridges; but from the size of some of the residual bodies, it was suspected that they were formed by coalescence of more than one cytoplasmic lobe. Freeze‐fracture demonstrated few intramembranous particles on either the P or E face of the plasma membrane forming the bridge; this finding suggested bridge structures restricted free lateral movement of membrane constituents across the bridge. Collectively, the date demonstrated that bridges are not static structures but show size variations and considerable structure‐related diversity during sper

ISSN:0002-9106    

DOI:10.1002/aja.1001800102

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

年代:1987

数据来源: WILEY

摘要:

AbstractFilaments about 6–7 nm in diameter were seen associated with germ cell intercellular bridges in detergent‐permeabilized cells treated with tannic acid. Approximately 40–50 filaments were present subjacent to the bridge density. Filaments encircled the bridge channel in a manner similar to contractile ring actin filaments of dividing cells. NBD‐phallacidin and myosin S‐1 subfragments were employed to demonstrate that the filaments observed at intercellular bridges are actin. Intratesticular injection of a single dose of cytochalasin D, a specific inhibitor of actin filaments, caused certain intercellular bridges of spermatids to open within 3 hr after injection, leading to the production of symplasts. During bridge opening, remnants of bridge densities were gradually incorporated into the lateral aspect of the plasma membrane of the symplast. Thus actin, present in bridge structures, appeared to participate in maintaining certain intercellular bridges. A model of intercullar bridge structure is

ISSN:0002-9106    

DOI:10.1002/aja.1001800103

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

年代:1987

数据来源: WILEY

摘要:

AbstractLeydig cell ultrastructure and function in diabetic rats were studied by concurrent cytochemisty, morphometry, and testosterone assay. The streptozotocin (Stz) model was modified to include nondiabetic Stz‐injected rats, an insulin‐treated diabetic group, and semistarved animals in addition to controls and untreated diabetic rats. The separation of the effects of diabetes, Stz, semistarvation, and insulin treatments was achieved by application of orthogonal contrast statistics.After 3 months of treatments, testes were perfusion fixed, incubated Δ5,3β‐hydroxysteroid dehydrogenase (HSD) activity, and processed for electron microscopy.Diabetes increased Leydig cell smooth endoplasmic reticulum (SER), increased mitochondrial and lipid content, decreased HSD staining, and decreased serum testosterone levels. Insulin treatment reduced SER and increased testosterone concentrations. Semistarvation also increased SER and reduced testosterone levels but did not alter HSD staining. Stz had no significant effect on these variables. The results suggested that the hypoandrogen state was due to a primary Leydig cell compromise and not solely to malnutrition and that it was correctable by insulin tr

ISSN:0002-9106    

DOI:10.1002/aja.1001800104

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

年代:1987

数据来源: WILEY

摘要:

AbstractProtein synthesis in epididymal tissue of intact and castrated rabbits was studied after incubation of epididymal minces with [35S]‐cysteine or [35]‐methionine and protein separation by two‐dimensional gel electrophoresis. Regional differences in the pattern of protein synthesized were observed. Castration did not change overall protein synthesis, but it reduced these regional differences. The presence of 5α‐DHT in the culture medium of the proximal corpus epididymidis perfused for 24 hr did not increase overall protein synthesis in tubules from intact or castrated rabbits and did not reinitiate synthesis of the proteins that had disappeared after castration.The kinetics of glycoprotein synthesis and secretion were studied by light and electron microscopy autoradiography at 0.5, 2, 6, and 24 hr after exposure to [3H]‐mannose, [3H]‐fucose, and [3H]‐glucosamine. Changes in the distribution of msinnose‐ and glucosamine‐labeled material indicated that the decline in grain density over the epithelium from 30 min to 24 hr coincided with an increasing reaction over the stereocilia border from 30 min to 2 hr and in thejumen from 2 to 24 hr. The distribution of fucose‐labeled material indicated that the grain reaction over the epithelium declined more rapidly than with the mannose label. When the glucosamine‐labeled sperm mass was released from the tubules, the labeled material was lost after the first washing, indicating that the glucosamine‐labeled glycoproteins did not bind firmly to corpus spermatozoa within 24 hr. After castration, both mannose‐ and fucose‐labeled materials migrated to the cell apex more rapidly than in the intact animal, but they were not released as readily into the lumen. The culture of epididymal tubules from castrated males with 5a‐DHT for 24 hr did not promote the release of either mannose‐ or fucose‐labeled material into the lumen. However, testosterone givenin vivofor 2 weeks restored secretion of manno

ISSN:0002-9106    

DOI:10.1002/aja.1001800105

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe sequence of events in the development of the brain in human embryos, already published for stages 8–15, is here continued for stages 16 and 17. With the aid of a computerized bubble‐sort algorithm, 71 individual embryos were ranked in ascending order of the features present. Whereas these numbered 100 in the previous study, the increasing structural complexity gave 27 new features in the two stages now under investigation. The chief characteristics of stage 16 (approximately 37 postovulatory days) are protruding basal nuclei, the caudal olfactory elevation (olfactory tubercle), the tectobulbar tracts, and ascending fibers to the cerebellum. The main features of stage 17 (approximately 41 postovulatory days) are the cortical nucleus of the amygdaloid body, an intermediate layer in the tectum mesencephali, the posterior commissure, and the habenulo‐interpeduncular tract. In addition, a typical feature at stage 17 is the crescentic shape of the lens c

ISSN:0002-9106    

DOI:10.1002/aja.1001800106

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

年代:1987

数据来源: WILEY

摘要:

AbstractCyst structures were often detected in and around thyroid glands of the dog. The present study revealed the frequency of occurrence, the light microscopic features, and the immunoperoxidase reactions to anti‐keratin and anti‐ldS‐thyroglobulin antisera of each cyst located in parathyroid III, parathyroid IV, thymus IV, C‐cell complexes, and thyroid parenchyma from 112 dogs. In each location, cysts showed characteristic features. In parathyroid III, the cysts were covered with single or pseudostratified epithelium composed of ciliated cells; whereas in parathyroid IV they were covered with keratinizing stratified squamous epithelium. In C‐cell complexes, small cysts lined with small packed cells were predominant, and large cysts lined with single cuboidal cells or stratified squamous cells were also present. In thymus IV located in the close vicinity of parathyroid IV, cyst epithelium consisted of several types of cells showing variable futures. In thyroid parenchyma, there were several types of cysts: some were covered with ciliated columnar cells, and others were covered with two or multilayers of small packed cells or cuboidal cells. In spite of these differences in appearance of the cysts located in different tissues, all their epithelia were immunoreactive to the keratin antisera, except for small cysts in C‐cell complexes, which were regarded as immature structures. Thus, the presence of keratin filaments in epithelial cells seems to be a characteristic feature of all cysts. The lumens of each cyst contained variable amounts of amorphous materials, which showed colloid‐like, flocculent, foamy, and granular features and were periodic acid‐Schiff‐positive in variable degrees, from weak to intense. Although the lumenal contents of the cysts in parathyroid III revealed no immunoreactivity for 19S‐thyrogIobulin, those in thyroid parenchyma, C‐cell complexes, parathyroid IV, and thymus IV reacted strongly with the 19S‐

ISSN:0002-9106    

DOI:10.1002/aja.1001800107

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe osmium‐ferrocyanide method for staining of the sarcoplasmic reticulum (SR) was used for a morphological investigation of the various components of the SR in the atrioventricular node and bundle (AVNB) cells of guinea pig hearts. On the basis of light microscopic observations, the AVNB tissue in guinea pig hearts can be divided into five regions: atrionodal junction, midnode, proximal bundle, distal bundle, and bundle branches. Electron microscopic observations revealed two types of junctional SR (j‐SR) saccules in the cells from all the regions of AVNB tissue. One is similar to that seen in the working cardiac cells, i. e., flattened saccules with junctonal granules. The second type is dilated and contains electrondense granular material throughout its lumen. The flattened type is seen more often than the dilated type in atrionodal junctional cells and midnode cells, whereas the dilated type occurs more often in distal bundle cells and bundle branch cells. In most cells from the atrionodal junction and midnode regions, the j‐SR saccules are apposed more often to sarcolemmal areas associated with nonspecialized regions of intercellular junctions than to other sarcolemmal areas. This distribution was not found in the distal bundle and bundle branch cells. Free SR tubules around the myofilament bundles are poorly developed in the midnode cells, generally in accord with the extent of development of myofibrils. Z‐tubules are found in cells from all regions but are poorly developed in midnode cells. Corbular SR vesicles are found in cells from all the regions of AVNB tissues but are rare in midnode cells. Thus, each of the regions in the AVNB tissue has a different, characteristic distribution of SR components. Because of their possible relationship to the regulation of the intracellular concentrations of calcium, these differences in SR morphology may contribute to the diverse physiological properties of the different regions of the AV node and

ISSN:0002-9106    

DOI:10.1002/aja.1001800108

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

年代:1987

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001800101

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

年代:1987

数据来源: WILEY