摘要:

AbstractThis manuscript considers certain aspects of mineral deposition in bone and other vertebrate calcifying tissues in order to examine physical, chemical, and biological factors important in the mineralization process. The paper in a discussion format principally presents new data and the formulation of concepts based on such data as well as a summary of background material as necessary review. Mineralization is found to occur at spatially independent sites throughout the organic extracellular tissue matrices. Matrix vesicles and collagen fibrils each may serve as independent nucleation centers for mineral with vesicle mineralization being local and collagen mineralization dominating the tissues as a whole. Collagen fibril organization is suggested to be such that hole zones are aligned in three dimensions, creating extensive channels for mineral accommodation. Nucleation occurs initially in hole zones and crystal growth leads to the development of plate‐like mineral particles whose orientation, disposition, and sizes within fibrils are detailed. Effects of diffusion, crystallinity, and critical nucleation and growth events are described with respect to their influence on mineral deposition in bulk and local regions of tissue matrice

ISSN:0003-276X    

DOI:10.1002/ar.1092300402

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

年代:1991

数据来源: WILEY

摘要:

AbstractEarlier studies have shown that the extracellular matrix (ECM) protein tenascin (TN) is present between uninjured epidermal cells of urodele appendages, but is absent from most of the mesenchymally derived ECM. Following appendage amputation, this distribution is reversed. TN is lost from the epidermis and appears in the ECM of the stump and the regeneration blastema. In the present study, monoclonal and polyclonal antibodies to TN were used to localize this protein immunohistochemically in limbs of the adult urodeleNotophthalmus viridescensat various stages following skin removal with or without damage to underlying muscle to determine (1) if the loss of TN by the epidermis and its gain by mesenchymal tissues occurs in wounds that do not require regulation by epigenetic mechanisms, and (2) if TN is present in the provisional wound matrix beneath migrating epidermal cells. In addition, skin explants were cultured on TN‐coated dishes to learn if TN possesses active sites that can support epidermal cell migration. The results indicate that simple wounding leads to the same TN patterns as occurs following limb amputation. Tenascin loss from the epidermis could be seen as early as 6 hr after wounding, a time during which migrating epidermal cells are moving over the wound bed. During this period, there was no evidence of TN in the provisional wound matrix. In contrast to collagen, which supports considerable epidermal cell migration from skin explants, TN allowed no more migration than did the inactive protein, myoglobi

ISSN:0003-276X    

DOI:10.1002/ar.1092300403

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe rat nasolabialis muscle is comprised of a mosaic of red, white, and intermediate muscle fiber types. Using computerized microdensitometry, cytochrome oxidase (COX) activity was quantitatively analyzed in each fiber type throughout the period of denervation and recovery in young adult (3‐month) and middle‐aged (15‐month) male Sprague‐Dawley rats. In animals of both age groups, the nasolabialis muscle on one side of the head was denervated by crushing the facial nerve. At specific days post crush (dpc) ranging from 2 days–2 months, animals were sacrificed and thick sections of normal and denervated muscles were incubated to demonstrate the activity of COX, a mitochondrial enzyme, which differentiates between the three fiber types. Enzyme activities in individual fibers were microdensitometrically analyzed using a digitizing image analyzer. Although a denervation‐induced decrease followed by eventual recovery occurred in all fibers of each type, age‐related differences were evident. For all types, younger fibers consistently showed decreased COX activity sooner than their older counterparts, and older fibers of all types consistently showed a greater decreased COX activity than the younger fibers. Denervation‐induced de‐differentiation of muscle fibers led to a more homogeneous population of fiber types in both age groups. Following recovery of function, the magnitude of the fiber enzyme activity change differed according to fiber type and to age, and was consistently smaller in older animals. The normal mosaic pattern of fiber type distribution and normal COX levels were restored 2 months after nerve lesion i

ISSN:0003-276X    

DOI:10.1002/ar.1092300404

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

年代:1991

数据来源: WILEY

摘要:

AbstractUsing specific polyclonal antibodies generated against a 13 KD human testicular inhibin, immunocytochemical localization of inhibin was carried out in different regions of human epididymis. The concentrations of inhibin were greater in caput and corpus regions as compared to the caudal region. The epididymal inhibin was found to be bioactive, since it suppressed specifically the FSH levels of rat pituitaries in vitro. Spermiophage/macrophage cells exhibited strong staining for inhibin which were suggestive of a possible role of inhibin in modulation of immune function. In view of the known activities of inhibin in cellular growth, differentiation, and steroidogenesis, epididymal inhibin could have a role in acquisition of sperm fertilizing capabilities.

ISSN:0003-276X    

DOI:10.1002/ar.1092300405

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

年代:1991

数据来源: WILEY

摘要:

AbstractInterstitial cells of Leydig characteristically occur in clusters around blood vessels. Often these clusters remain intact when interstitial tissues are mechanically separated from other components of the testis. The presence of strong intercellular attachments is most likely one of the factors responsible for Ground Squirrel Testis Vancouver, British Columbia, Canada V6T 1Z3, maintaining the integrity of Leydig cell clusters. In many tissues, actin associated adhesion junctions commonly provide intercellular attachment. To determine if actin associated adhesion junctions are present between Leydig cells, we have used 1) immunofluorescence to probe for two components that characterize these junctions in other tissues and 2) electron microscopy to examine areas of intercellular contact for evidence of microfilament related adhesion junctions.Isolated clusters of unsectioned cells, which had been fixed and detergent extracted, were probed with the F‐actin specific stains rhodamine phalloidin and NBD‐phallacidin and with an affinity purified primary antibody raised against human platelet vinculin. In regions of intercellular contact, fluorescence staining with the actin probes was intense and appeared as a solid linear band. Similar regions also stained with the vinculin probe. In double label experiments, actin and vinculin probes were co‐distributed at sites of intercellular contact.Zones of intercellular contact, apparently similar to those detected with fluorescence microscopy, were observed a t the ultrastructural level. At these sites, subsurface filaments, interpreted by us as actin, formed a dense carpet adjacent to the lasma membrane on each side of the junction. These filaments appeared to be organized into networks rather than discrete bundles.Our observations that 1) probes for actin and vinculin codistribute at certain sites of intercellular contact and 2) a layer of microfilaments is associated with the plasma membrane in electron micrographs of these contact regions support the conclusion that Leydig cells, at least in the ground squirrel, may possess actin associated adhesion junctions similar to those described between cells of numerous other

ISSN:0003-276X    

DOI:10.1002/ar.1092300406

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe distribution of Calmodulin was examined during spermiogenesis and sperm epididymal maturation in rabbit, hamster, mouse, rat, monkey, and human. An affinity‐purified antibody to Calmodulin was used to characterize this protein in sperm extracts by immunoblot analysis. Post‐embedding immunogold procedures were used to localize Calmodulin at the ultrastructural level. The pattern of Calmodulin distribution was similar in the six species studied. A diffuse labeling was observed in round spermatids. Gold particles accumulated first in the subacrosomal layer of elongating spermatids. The perinuclear ring was also labeled. During the maturation phase of spermatids, Calmodulin labeling extended to the postacrosomal sheath. Dramatic changes occurred at spermiation so that in testicular sperm Calmodulin immunostaining was predominant in the postacrosomal sheath. Some labeling was still detected in restricted areas of the subacrosomal layer. This feature varied from species to species. Calmodulin location did not change during sperm epididymal maturation. A role for Calmodulin in the control of manchette development and regulation of subacrosomal actin aggregation state during spermiogenesis is proposed. The unique location of Calmodulin in the postacrosomal sheath of all species that have been studied in this work, together with the known presence of calcium in this area suggest a pivotal role for Calmodulin in sperm‐egg fusion pr

ISSN:0003-276X    

DOI:10.1002/ar.1092300407

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe perforatorium is the subacrosomal portion of the perinuclear theca that encapsulates the nucleus of spermatozoa. In the rat, the perforatorium is a curved pointed structure, which in cross section is triangular in outline over the apical half and beyond the tip of the nucleus. The perforatorium, composed of several proteins, appears as a distinct structural entity only at the very end of spermiogenesis. In this study, polyclonal antibodies prepared against the entire isolated perforatorial fraction and against the major 16 and 34 kDa perforatorial polypeptides were used to determine the distribution of perforatorial proteins in germinal cells at various steps of differentiation. Immunoperoxidase staining at the LM level and quantitative immunogold labeling at the EM level were used. The labeling patterns with all three antibody preparations were identical. The immunolabeling first appeared in early pachytene spermatocytes and increased progressively, with a statistically significant upward trend, in both the nuclei and cytoplasm of spermatocytes and spermatids until step 9 of spermiogenesis. Up to this step the labeling concentration was significantly higher over the nucleus than over the cytoplasm. During nuclear condensation in steps 9 and 12 spermatids, there was a progressive loss of all the labeling over the nucleus and a corresponding increase of labeling over the cytoplasm. During steps 16–18, the early signs of condensation of perforatorial proteins occurred next to the inner acrosomal membrane. Then during step 19 there was a sudden condensation of perforatorial proteins into a definitive perforatorium. Thus proteins destined to form this cytoskeletal structure reside in both the nucleus and cytoplasm of spermatocytes and spermatids until nuclear condensation of the latter. Thereafter, they are restricted to the spermatid's cytoplasm and finally condense around the elongated nucleus at the end of spermiogenesi

ISSN:0003-276X    

DOI:10.1002/ar.1092300408

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

年代:1991

数据来源: WILEY

摘要:

AbstractMucous neck cells (MNCs) of the fundic gland are phylogenetically thought to have first appeared in amphibians. We studied the origin and differentiaion of MNCs in fundic glands ofXenopus laevis. By means of lectin histochemical methods usingGriffonia simplicifoliaagglutinin‐II (GSA‐II), MNCs were detected specifically in fundic glands of adultX. laevis. Mucous granules of MNCs were labeled by GSA‐II‐colloidal gold (CG) staining. Other cells such as surface mucous cells (SMCs), oxynticopeptic cells (OPCs), and endocrine cells did not react to GSA‐II.Ulex europaeusagglutinin‐I specifically stained OPCs, but not MNCs and SMCs. During the morphogenetic period of the stomach in metamorphosing larvae, GSA‐II reactive cells randomly appeared in various portions of the underdeveloped fundic glands and then rapidly localized in the neck portion. At this time, newly appearing mucous granules of MNC type were labeled by GSA‐II‐CG. Two types of cells intermediate to MNCs and SMCs and intermediate to MNCs and OPCs were observed in the larval gastric region. Cells intermediate to MNCs and OPCs were also found in adults. In these cells, mucous granules of MNC type were labeled by GSA‐II‐CG, but mucous granules of SMC type and zymogen‐like granules did not react to GSA‐II. These observations suggest that GSA‐II is a useful marker in studying the differentiation of MNCs and their precursors regardless

ISSN:0003-276X    

DOI:10.1002/ar.1092300409

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

年代:1991

数据来源: WILEY

摘要:

AbstractMonoclonal antibodies produced against rat small intestinal mucins were utilized to study variability of stored mucin granules within rat ileal goblet cells. Eleven antibody‐secreting hybridoma cultures were produced; six of these uniformly labeled stored mucin granules in virtually all goblet cells, suggesting that some antigenic features are common to all granules. The other five stained goblet cells in the rat small intestinal epithelium nonuniformly. R803, R805, and R807 localized within almost all goblet cells but revealed differential labeling of centrally and peripherally located mucin granules. R804 uniformly labeled the mucin granules of most villous goblet cells; some of the crypt goblet cells were uniformly labeled, but the majority were only partially labeled, resulting in a mottled staining pattern. R808 stained only a small portion of crypt goblet cells; there is, however, an increase in both number of goblet cells labeled and in uniformity of staining of the stored granule mass from the base of the crypt to the surface, resulting in uniform labeling of virtually all goblet cells at the villus tip. This study demonstrates for the first time that rat small intestinal mucin granules are immunologically heterogeneous and nonuniformly distributed within the epithelium. Additionally, staining patterns within the stored granule mass suggest that structurally distinct subpopulations of mucin granules may exist within a single goblet cel

ISSN:0003-276X    

DOI:10.1002/ar.1092300410

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

年代:1991

数据来源: WILEY

摘要:

AbstractVariations in immunoreactivity for cathepsin H in rat type II alveolar epithelial (type II) cells and in its proteolytic activity in bronchoalveolar lavage fluid (BALF) were examined at six evenly spaced times over 24 hr (light period: 0600–1800 hr). Ring‐shaped immunodeposits for cathepsin H were detected in type II cells (lamellar bodies), their sizes varying over 24 hr. The large ring‐shaped immunodeposits increased during the light period, decreasing rapidly from 2000 to 0000 hr. Small intense immunodeposits abundantly appeared in the cells at 0000 hr. The area densities of immunodeposits in type II cells and their optical densities also varied with the time of day; both densities were high during the dark period, peaking at the mid dark period, whereas they were decreased during the light period. Proteolytic activities of cathepsin H in BALF (6 ml/rat) examined at each time revealed a distinct variation over 24 hr, corresponding to the variation in the immunoreactivity in type II cells. The activities in BALF were high from 1600 to 0400 hr and low at 0800 hr. These results suggest that the variation in immunoreactivity for cathepsin H in type II cells over 24 hr reflects the intracellular growth of lamellar bodies and secretory activity of the cells. Similar variations in the immunoreactivity and proteolytic activity of cathepsin H in the cells and BALF indicate its cosecretion with surfac

ISSN:0003-276X    

DOI:10.1002/ar.1092300411

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

年代:1991

数据来源: WILEY