Apical cytoplasm

About: Apical cytoplasm is a research topic. Over the lifetime, 1080 publications have been published within this topic receiving 36131 citations.

Synthesis of glycoproteins in the Golgi complex of the mouse gallbladder epithelium during fasting, refeeding, and gallstone formation. A light microscopic autoradiographic and quantitative electron microscopic study.

Abstract: The mouse gallbladder epithelium was studied with light microscopic autoradiography and quantitative electron microscopy during fasting, refeeding and experimental gallstone formation. To determine the intracellular pathway of glycoproteins, H3-galactose was injected at different time intervals into the mice. At 10, 25 and 40 min after an intraperitoneal injection the gallbladders were fixed and prepared for light microscopy. As early as 10 min after injection, label was observed in supranuclear cytoplasmic regions and at 25 min, an increased radioactivity was present throughout the apical cytoplasm. At 40 min, silver grains were mainly present at the cell surface. Autoradiographs processed 25 min after an intraperitoneal H3-galactose injection after fasting for 48 h showed decreased supranuclear and apical radioactivity. After refeeding (12 h) there was an enhanced activity in both these regions. Animals fed a lithogenic diet for one month showed a marked increase of radioactive label mainly in cells of crypts and invaginations of the mouse gallbaldder mucosa. Morphometric measurements of the Golgi apparatus revealed that deprivation of food significantly dimished the volume density of the Golgi apparatus. Refeeding the amimals restored the volume density values to normal levels, In the course of gallstone formation there was a further significant increase in the volume density of the Golgi complexes as compared to controls.

Postnatal development and differentiation of the opossum submandibular gland.

Abstract: The postnatal development and differentiation of the submandibular salivary gland has been examined in sixteen groups of young opossums. At birth the glandular elements, dispersed in loose connective tissue, consist only of ducts that are immature in appearance and of irregular secretory end-pieces. Development occurs in two phases, the first from birth to approximately 31 days postnatum, and the second thereafter. During the first phase the ductular elements show separation into intercalated and intralobular ducts, and attain structural maturity. The larger ducts are concentrated centrally within each lobule and lie in a markedly vascular connective tissue. The secretory end-pieces, initially acinar in form, are lined by proacinar cells which exhibit intercellular canaliculi at the lateral cell membranes and a few dense granules in the apical cytoplasm. During the second phase of development extensive changes occur within the secretory end-pieces, which elongate to form a system of branching tubules. Component cells show an increased granular content, and those in the main body of the tubules differentiate into mucous cells. By 34 cm postnatum the proacinar cells in the bulbous endings of the tubules are replaced by special serous cells possessing intercellular canaliculi and secretory granules which are either electron-lucent or electron-dense. The sequence of changes that occur during postnatal development is discussed and related to possible functional activities. The early development of the ducts may be correlated with their role in homeostasis, while the later development of secretory tubules and the differentiation of secretory cell types may be related to the onset of weaning, and may possibly be induced by this major change in dietary habit.

The profile of the epidermal growth factor system in rat endometrium during postpartum involution period

Abstract: The epidermal growth factor (EGF) plays a crucial role in the control of uterine cell proliferation, growth and differentiation. This study was designed to investigate the spatiotemporal expression pattern and localization of the EGF receptor/ligand system during the process of uterine involution using immunohistochemistry. Our results indicated that the expression of the ErbB/HER receptors and their ligands varied with structural changes in the uterus at different days of involution. Supranuclear punctate ErbB1 immunostaining was observed in the luminal and glandular epithelial cells and endometrial fibroblasts. Moderate ErbB2/HER2 immunoreactivity was observed in the lateral membrane and cytoplasm of the epithelial cells on the 1st, 3rd and 5th days and was decreased on the other days of involution. The amount of nuclear and cytoplasmic ErbB3/HER3 and ErbB4/HER4 immunostaining remained constant throughout the postpartum period. The EGF immunoreaction was weak in the luminal and glandular epithelium throughout the involution period. Although the cytoplasmic AREG immunoreactivity in the glandular epithelium was stronger on the 1st and 3rd days compared with the other days of involution, NRG1 immunostaining was weak on the 1st and 3rd days and was moderate in the apical cytoplasm on the 10th and 15th days of involution. The macrophages displayed strong cytoplasmic immunoreactivity for ErbB3/HER3, ErbB4/HER4, EGF, AREG and NRG. Strong, moderate and weak immunostaining for ErbB2/HER2, ErbB4/HER4 and other proteins (ErbB1, ErbB3, AREG and NRG), respectively, was present in the myometrial smooth muscle cells. These findings support the hypothesis that the EGFsystem plays a role in the development of various physiological changes associated with uterine involution.

Localization of cystic fibrosis transmembrane conductance regulator signaling complexes in human salivary gland striated duct cells.

Abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic AMP-dependent protein kinase (PKA)-regulated Cl(-) channel, crucial for epithelial cell regulation of salt and water transport. Previous studies showed that ezrin, an actin binding and A-kinase anchoring protein (AKAP), facilitates association of PKA with CFTR. We used immunohistochemistry and immunogold transmission electron microscopy to localize CFTR, ezrin, and PKA type II regulatory (RII) and catalytic (C) subunits in striated duct cells of human parotid and submandibular glands. Immunohistochemistry localized the four proteins mainly to the apical membrane and the apical cytoplasm of striated duct cells. In acinar cells, ezrin localized to the luminal membrane, and PKA RII subunits were present in secretory granules, as previously described. Immunogold labeling showed that CFTR and PKA RII and C subunits were localized to the luminal membrane and associated with apical granules and vesicles of striated duct cells. Ezrin was present along the luminal membrane, on microvilli and along the junctional complexes between cells. Double labeling showed specific protein associations with apical granules and vesicles and along the luminal membrane. Ezrin, CFTR, and PKA RII and C subunits are co-localized in striated duct cells, suggesting the presence of signaling complexes that serve to regulate CFTR activity.