Ultrastructural and immunocytochemical study of the leptomeres in the mouse cardiac muscle fibre

The three-diiiiensional configuration and cheiriicol composition of leptoniei-es in the inouse \ e i i t r i c ~ i l a r cardiac inuscle fibre were electron iiiicroscopically und iminuiiocytochemically in\-estigated ~ising seinithin sections and specific antibodies agairist actin. the intei-mediate filament proteins desinin and viiiientin. anci the aciin-binding proteins a-actiriin, filainin and vinculin. The leptomeres appeared columnar in shape arid periodically segmeiited by electron-dense tiisc-like septa. The electrori-lucent areas betweeri these septa uere composed of fiiie interlinked filainents running obliquely to the major axis cif the Ieptomere. Actiii was localized in the electron-dense lii-ies of the leptoineres but not in the fine filaments. No reaction was. however. detected for desinin. vinientin. \zi~iculin. rilainin and a-actinin. The preserit results suggest. therefore. that the leptomeres inay not have a contractile functio

Páginas de Na-K-ATPase activity in the guinea pig stria vascularis in experimentally-induced endolymphatic hydrops

The effect of endolymphatic hydrops on the Na-K-ATPase activity in the guinea pig stria vascularis was electron microscopically and enzyme cytochemically investigated one year after experimental induction. The morphological observations revealed intercellular dropsy in the basal infoldings of the marginal cells, and shrinkage and disappearance of intermediate cells. Moreover, shrinkage of the marginal cells, especially of the basal infoldings, was occasionally observed. In spite of these morphological alterations, the Na-K-ATPase activity was still detected on the plasma membrane of the basal infoldings of most marginal cells. No remarkable differences were found among the cochlear turns of the specimens examined. However, no reaction product was detected on the basolateral plasma membrane of severely degenerated marginal cells. The present results indicate that the Na- K-ATPase of the plasma membrane of the basal infoldings of the marginal cells plays an important role in the maintenance of the unique ion concentration of the endolymph even in the endolymphatic hydropic condition, and that the Na-K-ATPase activity is attenuated in severely atrophic cells

Alkaline phosphatase, 5'-nucleotidase and magnesium-dependent adenosine triphosphatase activities in the transitional epithelium of the rat urinary bladder

The cerium-based method was used to demonstrate cytochemically the ultrastructural localization of alkaline phosphatase (ALPase), 5'- nucleotidase (5'-Nase) and magnesium-dependent adenosine triphosphatase (Mg-ATPase) on the transitional epithelium of the rat urinary bladder. The reaction product for ALPase was found on the plasma membrane of al1 epithelial cells, except the luminal surface of superficial cells. The activity of 5'-Nase appeared on the plasma membrane of al1 bladder transitional epithelial cells, including the free surface of superficial cells. The Mg-ATPase reaction product was seen on the plasma membrane of superficial, intermediate and basal cells, but never on the luminal surface of superficial cells and it was only occasionally seen on the basal surface. The possible functions of these phosphatases have been discussed, and it was emphasized that the 5'-Nase activity present on the luminal surface of superficial cells may play a special role in the membrane movement of these cells in the transitional epithelium

Fine structure of the acinar and duct cell components in the parotid and submandibular salivary glands of the rat: a TEM, SEM, and HRSEM study

Parenchymal and stromal components of the rat parotid and submandibular glands were examined by conventional and high resolution scanning electron microscopy (HRSEM). Freezefractured specimens were subjected to HCI and NaOH extraction procedures to better differentiate connective tissue and cellular components. In addition, the internal three-dimensional morphology of the secretory acinar cells and duct cells was revealed by maceration with a dilute osmium tetroxide solution to selectively remove some of the cytoplasmic components. SEM and HRSEM examination of the HC1- treated samples of both glands revealed a fine filamentous network immediately surrounding each acinus. Coarser bundles of collagen that linked neighboring acini were also observed. NaOH-extracted samples selectively removed the cellular components and showed more clearly the three-dimensional structure of the connective-tissue stroma. A densecollagenous network surrounded each lobule while more internal regions consisted of a honeycomblike pattern of evacuated spaces previously occupied by secretory acini. These spaces were smoothened in appearance and often interconnected. Apicallylocated secretory granules and profiles of the rough endoplasmic reticulum and Golgi apparatus in perinuclear regions were encountered in the acinar and duct cells of macerated samples by HRSEM. In addition, a phenylephrine-induced experimental condition performed in some rats resulted in a significant increase in secretory granule size and density of the serous cells