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Apical cytoplasm
About: Apical cytoplasm is a research topic. Over the lifetime, 1080 publications have been published within this topic receiving 36131 citations.
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TL;DR: The epididymis of the fan‐throated lizard Sitana ponticeriana was examined with light and transmission electron microscopy to understand the cellular mechanisms of fabrication of secretion granules in epithelial principal cells, granule release into the lumen, and the fate of the dense structured granules after reaching the lume.
Abstract: The epididymis of the fan-throated lizard Sitana ponticeriana was examined with light and transmission electron microscopy to understand the cellular mechanisms of fabrication of secretion granules in epithelial principal cells, granule release into the lumen, and the fate of the dense structured granules after reaching the lumen. Principal cells of the ductus epididymis, except at the cauda, secrete electron-dense biphasic granules copiously, which decrease in abundance from the initial segment to corpus. The principal cell possesses a prominent Golgi apparatus and all versions of endoplasmic reticulum (ER), rough, smooth, and sparsely granulated. The material of the dense portion of the secretion granules, after processing at the Golgi apparatus, appears to accumulate in large ER cisternae in the supranuclear cytoplasm. It undergoes condensation when the cisternae become condensing vacuoles. Mitochondria appear to play a role in dense granule formation. The condensing vacuoles are displaced toward the apical cytoplasm when the material of the less dense portion is added to the condensing vacuoles at the Golgi area. Thus, the less dense and dense portions of the secretion granules are secreted and added to the condensing vacuoles separately. The composite granules are released into the lumen by exocytosis when the less dense portion merges with the luminal content, whereas the dense portion maintains its structured identity. The latter, initially measuring 1-2 microm in diameter, increases in size several times. It is inferred that these granules release their content gradually, resulting in the appearance of vacuoles, and suggesting that the granules have an insoluble matrix in which there is a sparingly soluble material. The substance leaching out of the granules appears to contribute to keeping the sperm quiescent and alive during storage in the male reproductive tract.
17 citations
TL;DR: The present study suggests that the secretion in nasal gland is more strongly regulated by the autonomic nerves than in other exocrine glands.
Abstract: The nasal gland in the respiratory mucosa of guinea pig was studied by electron microscopy. The terminal portion of glands is composed of the secretory cells which are regarded as serous cells from the cytological point of view. The apical cytoplasm of these cells contains secretory vacuoles with watery appearance, but these vacuoles are greatly variable in number from cell to cell. The lateral surfaces of secretory cells are provided with elaborated cytoplasmic folds occurring mainly at the basal half of cell, by which adjacent cells are interdigitated. This structural feature of lateral surface, together with the watery appearance of secretory vacuoles in the apical cytoplasm, suggests that the secretory cells uptake a large amount of water or some electrolites from the interstitial tissue to secrete the watery products into the lumen. The nerve endings are frequently found embedded in the intercellular spaces between adjacent secretory cells of nasal gland. The nerve endings are presumed to be represented by a beaded swelling portion of axon, and contact directly with the lateral surface of secretory cells. The present study suggests that the secretion in nasal gland is more strongly regulated by the autonomic nerves than in other exocrine glands.
17 citations
TL;DR: Investigating the acid and alkaline phosphatase of the digestive tract of Hemisorubim platyrhynchos highlighted its role in the nutrient absorption primarily in the anterior intestine but also being essential in pH regulation because this is a carnivorous species with many gastric glands with secretions that could damage the intestine.
17 citations
Journal Article•
TL;DR: It was considered that, owing to its role in protein synthesis, the basal cytoplasm of the pancreatic exocrine cells in starved rats might be protected as far as possible during long-term starvation.
Abstract: Ultrastructural changes of the pancreatic exocrine cells after 3, 7, 14, 21, 28, 35 and 42 days of starvation were observed in male rats aged from 16 to 18 months weighing between 600 and 700 grams. The number of zymogen granules after starvation decreased to less than about 70 per cent of that of the control. Changes in the rough endoplasmic reticulum were hardly seen up to 14 days of starvation as compared with the control, but were observed in the apical and basal cytoplasm of the cell from 21 days after starvation. Particularly in 35- and 42-day starved rats, the rough endoplasmic reticulum was frequently shortened and dilated, and changed to disorganized membranous structures. The lysosomes in the apical cytoplasm of the cell gradually increased in number after starvation, and contact or fusion between the zymogen granules and lysosomes (viz, so-called crinophagy) was often seen at 35 and 42 days of starvation. Large autolysosomes especially those containing zymogen granules and rough endoplasmic reticulum were also marked in the basal cytoplasm of the cell after 35 and 42 days of starvation. Alterations in the basal cytoplasm of the cell appeared later than those in the apical cytoplasm. It was considered that, owing to its role in protein synthesis, the basal cytoplasm of the pancreatic exocrine cells in starved rats might be protected as far as possible during long-term starvation.
17 citations
TL;DR: A model for ion cycling between the exoskeleton and granules is presented and calcium was identified in the two larger granule types using X-ray microanalysis and significant amounts of phosphorus and potassium were also present in the large granules.
Abstract: Holthuisana transversa reabsorbs much of its exoskeletal calcium in the last 3 days before ecdysis and stores it in circulating granules in the haemocoel and in non-circulating granules in the subepidermal connective tissue. Calcium enters the epidermal cells from the moulting fluid, probably through their apical microvilli and is either incorporated into intracellular calcium granules or exits the cell via the basolateral membranes to be used in formation of two other granule types. Intracellular granules (0.4–2 μm long) form in large masses in the apical cytoplasm of the epidermal cells. They are formed as membrane-bound vesicles by the Golgi, and calcium and organic matrix material are added from the surrounding cytoplasm. As development proceeds, lamellae appear and calcium carbonate is deposited in the matrix. Granule masses move basally and are stored in the connective tissue. Calcium is also incorporated into extracellular large granules (0.8–3.8 μm long) which are formed in narrow intercellular channels between epidermal cells. A third granule type (small granules, 0.26 μm diameter) is formed in subepidermal connective tissue cells and released into the haemolymph in very large numbers. Calcium was identified in the two larger granule types using X-ray microanalysis and significant amounts of phosphorus and potassium were also present in the large granules. A model for ion cycling between the exoskeleton and granules is presented.
17 citations