13 research outputs found
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