Apical cytoplasm

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

Surface morphology and functions of pharyngeal structures in the larval lamprey Petromyzon marinus.

Abstract: To gain insight into the multiple functions of a complex biological structure, the morphology of the pharynx of the larva (ammocoete) of the lamprey Petromyzon marinus was investigated with scanning electron microscopy and histochemistry (PAS and Alcian blue). Features studied include the gills, the parabranchial chambers external to the gills, intrapharyngeal ciliary tracts, the ridged pharyngeal roof, the floor, and the intrapharyngeal taste buds. Significant findings are: (1) All (nonciliated) cells lining these structures are covered with microvilli or microridges. The pattern and packing density of these membrane features vary among different pharyngeal structures. The lumenar membranes of pharyngeal lining cells overlie a mucous prosecretion in the apical cytoplasm, suggesting that the microvilli/ridges on these membranes function to anchor mucus. (2) Patterns of microvilli/ridges on the gill respiratory lamellae differ among ammocoetes of different species. (3) Pharyngeal osmo-regulatory cells (“chloride cells”) could not be identified on the basis of the microvillus/ridge pattern. (4) Two types of ciliary tracts are present within the pharynx. One has tall (x= 13 μm) and densely packed cilia, whereas the other has shorter (x= 7 μm) and less densely packed ones. Because mucus covers both types of tracts their function appears to involve the transport of mucus. (5) Food particles were found on the lateral surfaces of the gill filaments and on the surfaces of the parabranchial chambers. It appears that goblet cells in the epithelia of these regions secrete mucus in which the particles are trapped.

Studies on the posterior silk gland of the silkworm Bombyx mori. VI. Distribution of microtubules in the posterior silk gland cells.

Abstract: There are two microtubule systems in the posterior silk gland cells. One is a radial microtubule system in which the microtubules run radially from the basal to the apical cytoplasm and in which fibroin globules (secretory granules of fibroin) and mitochondria are arranged along these microtubules, thus composing a "canal system" which is assumed to be responsible for the intracellular transport of fibroin globules. The other is a circular microtubule system in the apical cytoplasm which is composed of bundles of microtubules and microfilaments running in a circular arrangement around the glandular lumen at an interval of approximately 4 mum at the end of the fifth instar. This system is presumably concerned with secretion and/or intraluminal transport of fibroin.

Histochemical studies of Ca-ATPase, succinate and NAD+-dependent isocitrate dehydrogenases in the shell gland of laying Japanese quails: with special reference to calcium-transporting cells.

Abstract: In order to elucidate the problem of which cells are involved in calcium transport and to estimate the role of mitochondria in calcium transport in the avian shell gland, the fine structure and the Ca-ATPase, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide (NAD+)-dependent isocitrate dehydrogenase (NAD+-ICDH) activity of the shell gland of egg-laying Japanese quails were examined. The surface epithelial cells, consisting of ciliated cells with cilia and microvilli and non-ciliated cells with microvilli, had many large and electron-dense granules. The tubular-gland cells occupied the proprial layer and lacked secretory granules. When an egg was in the shell gland, the well-developed mitochondria of tubular-gland cells characteristically tended to accumulate in the apical cytoplasm, while they were scattered throughout the cytoplasm when an egg was not in the shell gland. Intense Ca-ATPase activity was found on the microvilli of tubular-gland cells, and moderate activity was found on the lateral-cell surface. In the surface epithelial cells, the basolateral cell surface showed moderate enzymatic activity. Both SDH and NAD+-ICDH activity were found in tubular-gland cells when an egg was in the shell gland. These results strongly suggest that calcium for eggshell calcification is actively transported by the tubular-gland (depending on Ca-ATPase activity) and that the mitochondria of gland cells may play an important role in this process as an energy source.

Immunohistochemical analyses on albumin and immunoglobulin in acute hypertensive mouse kidneys by "in vivo cryotechnique".

Abstract: Summary The purpose of this study is to visualize topographical changes of serum proteins, albumin and immunoglobulin, passing through mouse glomerular capillary loops and their reabsorption in renal proximal tubules by immunohistochemistry in combination with our ?in vivo cryotechnique? The ?in vivo cryotechnique? was performed on left mouse kidneys under normotensive, experimentally acute hypertensive and heart-arrest conditions The cryofixed tissues by the technique were routinely processed for freeze-substitution Serial deparaffinized sections were stained with hematoxylin-eosine and immunostained with anti-mouse albumin, immunoglobulin G (IgG), kappa or lambda light chain and IgG1 heavy chain antibodies Under the normotensive and heart-arrest conditions, albumin and IgG were clearly immunolocalized in blood vessels and slightly in apical cytoplasmic parts of some proximal tubules Under the acute hypertensive condition, the albumin and kappa or lambda light chains, but not IgG1 heavy chain, were strongly immunolocalized in the apical cytoplasm of almost all proximal tubules This study is the first in vivo visualization for glomerular passage of serum proteins and their transtubular absorption Thus, the ?in vivo cryotechnique? with freeze-substitution can be used for clarifying not only the functional morphology of living animal cells, but also in situ immunohistochemical localization of their components Histol Histopathol 20, 807-816 (2005)