Apical cytoplasm

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

Mucus Secretory Vesicles in Conjunctival Epithelial Cells of Wearers of Contact Lenses

Abstract: • Biopsy specimens from the upper tarsal conjunctivae of ten patients with clinically evident contact-lens-associated giant papillary conjunctivitis (GPC) and eight asymptomatic contact lens wearers without clinically evident conjunctival changes were compared by light and transmission electron microscopy to determine the contribution of nongoblet epithelial cells to increased mucus. A control group consisted of five subjects who had never worn contact lenses. The apical cytoplasm of superficial nongoblet epithelial cells in specimens from all groups showed single-membrane-limited vesicular inclusions that stained metachromatically with toluidine blue and were positive with PAS staining, which indicated mucoprotein content. Some vesicles appeared to discharge their contents into the conjunctival sac. More vesicles were found in the GPC subjects and the asymptomatic contact lens wearers than in the normal subjects. These observations, coupled with the sign of increased or excessive mucus discharge in GPC subjects and in asymptomatic lens wearers, support the premise that the superficial layers of nongoblet conjunctival epithelial cells can contribute to an increase in mucus production.

Structure and function of the intestinal epithelial cells in the perch (perca fluviatilis l.)

Abstract: An ultrastructural study of the intestinal absorptive epithelium in perch (Perca fluviatilis) has shown that the perch intestine can be divided into three segments: the proximal segment, the middle segment and the distal segment. The enterocytes of the proximal segment are found to be concerned with lipid absorption. The adsorbed fat gives rise to the presence of two forms of inclusions: lipid particles and lipid droplets. Enterocytes of the middle segment exhibit the typical ultrastructural features of pinocytosis; these consist of extensive invaginations of the luminal surface membrane and acculation of vacuoles in the apical cytoplasm. Exogenous proteins are ingested by absorptive cells from the intestinal lumen by a process similar to that described in neonatal mammals. In the distal segment the absorptive cells have few, short microvilli. Besides the absorptive epithelial cells, goblet cells, endocrine cells, pear-shaped cells, and plasma cells are occasionally found.

Ultrastructure of the mouse epididymal duct with special reference to the regional differences of the principal cells

Abstract: It is generally known that spermatozoa aquire the capacity for fertilization during passage through the proximal region of the epididymal duct and are then stored in the distal region of the duct (BEDFORD, 1975; HAMILTON, 1975). The mouse epididymal duct has been divided into five segments (I-V) by light microscopy; Segments I, II and III constitute the head of the epididymis, Segment IV the body, and Segment V the tail; Segments I, II and III seem to belong to the proximal region, and Segments IV and V to the distal region (TAKANO, 1980). In this electron microscope study, we have examined the regional differences of the principal cells of the epididymal duct to understand the functional significance of each segment.The principal cells decrease in height distalwards from Segments I to V. The nucleus is situated basally in the cells, with a well developed Golgi apparatus located above it. The endoplasmic reticulum in Segments I, II and III is generally vesicular, and is distributed throughout the cytoplasm. The ribosomes attached to the endoplasmic reticulum increase in number from Segments I to III. In Segments IV and V, flattened rough endoplasmic reticulum is seen in the basal cytoplasm of the cells. The multivesicular bodies are usually located in the supranuclear cytoplasm. They are large in Segment II and frequent in Segments II and IV. The dense bodies are specific in appearance for the cells in each segment. They are seen in the supranuclear cytoplasm in Segment I and in the infranuclear cytoplasm in Segments III, IV and V. Few dense bodies are found in Segment II. The apical cytoplasm contains coated and non-coated vesicles. These vesicles consist of large and small types in Segments I, II and III. They are of the small type in Segments IV and V. The luminal surface membrane has coated or non-coated invaginations between stereocilia.The findings suggest that the principal cells have secretory and absorptive functions specific for each segment. Discussion shall be made on the possibility that the secretion of the specific epididymal substances may provide the fertilizing ability to spermatozoa and the absorption pertains to the testicular fluid, epididymal secretions and substances bound to spermatozoa.

On the morphology of the human Sertoli cell.

Abstract: As revealed by light microscopical investigations the human Sertoli cell presents different appearances according to the pattern of infranuclear cytoplasmic inclusions. Although two or three stages of spermatogenesis are seen in a single cross section of a seminiferous tubule the Sertoli cells all show virtually the same features in such a cross sectioned tubule. The different appearances are also evident under the electron microscope. Although no obvious correlation was found with the stages of spermatogenesis in the seminiferous epithelium, the Sertoli cell appearances described here may be assumed to represent different metabolic situations. Other features of Sertoli cell ultrastructure are discussed such as the presence of residual bodies in the apical cytoplasm, glycogen-rich areas protruding towards the tubular lumen or the extracellular space, and membrane bound, round structures, found between the membranes of the smooth endoplasmic reticulum and resembling the “microbodies” of steroid producing cells.

Immunohistochemical distribution of immunoglobulins, lactoferrin, and lysozyme in human minor salivary glands

Abstract: The immunofluorescence technique was used to examine the distribution of immunoglobulin A and its subclasses, secretory component (SC), J chain, lactoferrin and lysozyme in labial and lingual (von Ebner's) glands. IgA-containing plasma cells were found in the connective tissue around intercalated or intralobular ducts and a few were noted around acini of both glands. IgA was detected in the apical cytoplasm of intercalated and intralobular duct cells and in acini of von Ebner's glands and in demilunes of labial glands. Most IgA-containing cells also stained for J chain. The ratio of IgA1:IgA2-containing cells was approximately equal in von Ebner's and labial glands. Cytoplasmic and surface membrane-related staining for SC was detected in epithelial cells of the intercalated and intralobular ducts in both glands, in the serous acini of von Ebner's gland, and in the demilunes of labial glands. Lactoferrin was found in serous acini, demilunes, intercalated and intralobular ducts. Lysozyme was found in acinar and intercalated ducts, but was rarely seen in intralobular ducts. These results disclose the presence of cells (plasma cells and epithelial cells) and their products (IgA and secretory component) that indicate the local production of secretory IgA in minor salivary glands.