Apical cytoplasm

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

The cytoskeleton in development of epithelial cell polarity

Abstract: The polarization of intestinal epithelial cells and the stereotypic arrangement of their actin-based cytoskeleton have made these epithelia an excellent system to explore the organization and formation of a cortical actin-based cytoskeleton. Through a combined morphological and biochemical analysis, the molecular arrangement of many of the components of the brush border has been elucidated. Study of brush border assembly in the Crypts of Lieberkuhn suggests that cytoskeletal mRNA and protein expression, as well as morphological development, occur rapidly following cell differentiation. Protein kinases appear to be important regulators of intestinal cell growth, for differentiating cells in the crypts possess 15-fold higher levels of tyrosine phosphorylated proteins than differentiated cells of the villus. One of these kinases, pp60c-src, has a 4- to 7-fold higher activity in crypts and increased association with the cytoskeleton than it has in villus cells. The development and maintenance of polarization in epithelial cells require the targeting and transport of specific proteins to the apical and basolateral plasma membrane. It has been proposed that a dynein-like, microtubule-based motor is involved in the transport of apically directed materials from the trans-Golgi to the apical plasma membrane. However, microtubules do not reach the plasma membrane, but terminate below the actin-rich network of filaments comprising the terminal web. We propose that vesicles translocate from the Golgi to the apical cytoplasm along microtubules using dynein, and then move through the terminal web to reach the apical plasma membrane using the actin-based motor myosin-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphology of the bovine epididymis.

Abstract: The epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II-V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 micron in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 microns in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well-developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II-VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogeneous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.

Effect of thiol-oxidation of glutathione with diamide on corneal endothelial function, junctional complexes, and microfilaments.

Abstract: Intracellular-reduced glutathione (GSH) was removed by thiol-oxidation with diamide during in vitro perfusion of the corneal endothelium. By 15 min the normal mosaic-like pattern of the endothelial cells was disrupted by serpentine-like lines of cell separation at the cell juntions. After 45 min of perfusion, infividual clusters of cells formed cup-shaped islands. The resultant exposure of Descemet's membrane to the perfusion solution resulted in corneal swelling. Transmission electron microscopy revealed that the endothelial cells separated at the apical junctions and that the microfilaments in the apical cytoplasm of cells formed dense bands, whereas the other subcellular organelles were normal in appearance. The change in cellular shape may be due to loss of cellular adhesion which results in the condensation of the microfilaments or contraction of the microfilaments. The addition of glucose to the perfusate prevented the diamide effect, and the diamide effect could be reversed upon removal and perfusion of a glutathione bicarbonate Ringer's solution. These results suggest that the ratio of reduced to oxidized glutathione in the endothelial cells plays a role in the maintenance of the endothelial cell barrier function.

Ultrastructure of the normal adult human female prostate gland (Skene's gland).

Abstract: The predominant cells of female prostatic glands lining their lumen were found to be tall cylindrical secretory cells with short stubby microvilli, protuberances of the apical cytoplasm, and with bleb formation. Abundant secretory vacuoles and granules, rough endoplasmic reticulum, developed Golgi complexes and numerous mitochondria are characteristic of their active secretory configuration with apocrine (apical blebs) and merocrine (secretory vacuoles and granules) type of secretion. Basal (reserve) cells were seen to be located between the secretory (luminal) cells and the basement membrane. Their ground cytoplasm is dense with rough endoplasmic reticulum and mitochondria. Their nuclei, unlike those of secretory cells, possess more peripheral condensed chromatin, denser dispersed chromatin and sporadic nucleoli. Besides the two basic types of mature prostatic cells intermediary cells were also seen, located between the basal and secretory cells or in their close vicinity. Their cytoplasm exhibits numerous profiles of rough endoplasmic reticulum and free ribosomes. Secretory vacuoles and granules were mostly practically absent (type 1 intermediary cells) so that they resembled basal (reserve) cells. In some of them, however, as in secretory cells, such secretory elements do gradually appear (type 2 intermediary cells). The finding of intermediary cells in the lining of prostatic glands supports the role of basal (reserve) cells in the renewal of cells in glands of the female prostate. The first ultrastructural analysis of the normal female prostate performed by transmission electron microscopy showed that, as in the postpubertal male, the prostatic glands in the adult female display mature secretory and basal cells. The results of the presented study further corroborate the contemporary concept of the female prostate as a functional genitourinary organ.