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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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Journal ArticleDOI
TL;DR: It is suggested that this transport might operate in situ and provide a morphological mechanism to explain a type of protein transport noted in the renal tubules of another flounder species by Maack and Kinter ('67).
Abstract: Large quantities of colloidal particles were rapidly transported around the junctional complex into the lateral intercellular spaces by flounder renal epithelial cells. Large invaginations containing particles developed in the apical cytoplasm of cells when tracer particles were injected into the tubular lumens. Some membranebounded profiles containing particles appeared close to the lateral intercellular spaces. Particles were then found in the lateral intercellular spaces, between the basal plasmalemma and the basement membrane, and within the basement membrane. It is suggested that this transport might operate in situ and provide a morphological mechanism to explain a type of protein transport noted in the renal tubules of another flounder species by Maack and Kinter ('67). It is interesting to consider that perhaps a similar mechanism for the transport of intact proteins might also operate in mammalian nephrons as well.

27 citations

Journal ArticleDOI
TL;DR: Goblet cells in the jejunal epithelium of adult and suckling rats were studied with transmission electron microscope and two or three different mechanisms of secretion discharge may possibly occur simultaneously in goblet cells.
Abstract: Goblet cells in the jejunal epithelium of adult and suckling rats were studied with transmission electron microscope. The use of triple fixation, i.e., osmium-aldehyde-osmium has some advantages in the preservation of mucous substances and some cell organelles. Cytochemical demonstration of polysaccharide and glycoprotein by methenamine silver as well as detection of TPPase and acid phosphatase (AcPase) were performed. Accumulation of secretory substances and combination with sugar moieties occurred in the internal sacs of Golgi lamellae, where TPPase activity was recognized. No rigid lamella usually positive to AcPase was found in goblet cells, though it was easily found in the columnar absorptive cells. AcPase was positive in some small immature mucus droplets as well as lysosomes.As the differentiation of goblet cells advances, mucus droplets come into contact and fuse to each other. As a result of the close contact of two adjacent membranes of mucus droplets, a pentalaminar structure is first formed. Then the central dense lamina disappears and the membrane becomes trilaminar. Disappearance of one of the apposed unit membranes, leaving another unit membrane, may take place. Finally the single unit membrane left between the adjacent droplets is also ruptured and complete fusion occurs.The mechanism of extrusion of mucous substance is complicated. Some mucus droplets located at the most superficial area may be released by the mechanism of exocytosis. More frequently, however, deeply located droplets fuse to each other and a huge vacuole is made in the apical cytoplasm. The substance filling the vacuole contains debris of cytoplasmic matrix and droplet membranes along with mucous secretory substance. These substances derived from different sources are expelled into the lumen at the same time. This may be classified into the apocrine mechanism, because a part of the cytoplasm and membranes are lost. The typical apocrine secretion, i. e., pinching off of cytoplasmic projection containing mucus droplets, was also found in the goblet cells. Thus, two or three different mechanisms of secretion discharge may possibly occur simultaneously in goblet cells.

27 citations

Journal ArticleDOI
TL;DR: The fine structure of the cerebellar cortex of the macaque fetus was examined at 75, 100, 125, 150, and 175 days after conception, and the relationship between maturation of the thyroid gland and of the Cerebellum in the macaques is discussed.
Abstract: The fine structure of the cerebellar cortex of the macaque fetus was examined at 75, 100, 125, 150, and 175 days after conception. Young Purkinje cells were recognizable in the 75 and 100-day old fetuses, occurring in clusters several layers deep. The rough endoplasmic reticulum in the Purkinje cells was limited to the perinuclear area and the region of apical cytoplasm adjacent to the plasmalemma. Neither dendritic processes nor synaptic contacts were seen on Purkinje cells at this time, although an occasional observation was made of synapses involving other cell types. Between 100 and 125 days, the cerebellar cortex matured rapidly. At the latter time, the Purkinje cells had a well developed dendrite, and axodendritic and axosomatic synapses were seen. At 150 days gestation age the Purkinje cells had well developed Nissl substance, and the axodendritic synapses were similar in structure to the adult spine contact. The relationship between maturation of the thyroid gland and of the cerebellum in the macaque is discussed.

27 citations

Journal ArticleDOI
TL;DR: It was concluded that the trophoblast of the placental villi is engaged in both hemotrophic and histotrophic nourishment of the embryo.
Abstract: The fine structure of the placental villi and the chorionic vesicles of the bush baby, Galago crassicaudata, were examined. The placenta was of the diffuse epitheliochorial type. The trophoblastic epithelium of the placental villi consisted of cells joined by tight junctions and desmosomes. The apical borders of these cells interdigitated with corresponding processes on the uterine epithelial cells. The fetal capillaries indented the trophoblastic cells later in gestation, and the trophoblast over the capillaries was correspondingly thinner with advancing gestation. The trophoblast of the villi was characterized by numerous lipid droplets and moderate amounts of granular endoplasmic reticulum (ER). The apical cytoplasm often had many mitochondria as well as small electron-dense vesicles and tubules. Uterine epithelial cells contained agranular ER and a well-developed Golgi apparatus. The apical cytoplasm contained numerous granules often with an electron-dense content. The uterine epithelial cells appeared to be secretory, contributing to the electron-dense material found between the fetal and maternal cells. Fetal capillaries were of the continuous type, whereas occasional fenestrae were observed in maternal capillaries. Recesses in the trophoblastic epithelium occurred at the tips, sides, and bases of the villi. These areas had taller trophoblastic cells that appeared to be more active in phagocytosing uterine content. The chorionic vesicles are invaginations of the chorion opposite the mouths of uterine glands. A layer of columnar trophoblastic cells covered the villi of the vesicles. These cells had abundant vacuoles and coated pits and vesicles. The mesodermal component of the chorionic vesicles included a capillary network and a layer of smooth muscle cells in the wall of the vesicle. It was concluded that the trophoblast of the placental villi is engaged in both hemotrophic and histotrophic nourishment of the embryo. The specialized chorionic vesicles are particularly important in providing histotrophic nutrients to the embryo, especially the secretions of the uterine glands. The similarity of the chorionic vesicles to the areolae of other species suggests they may be the pathway by which iron is transported from mother to fetus, perhaps by receptor-mediated endocytosis of macromolecules derived from uterine gland secretions.

27 citations

Journal ArticleDOI
TL;DR: Structural changes observed in choroid plexuses from rats dissected aboard a space shuttle demonstrated that choroidal epithelial cells display a modified organization in a microgravitational environment.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202112
20205
20195
20188
20175
201615