Showing papers on "Apical cytoplasm published in 1975"

The Sertoli cell junctional specializations and their relationship to the germinal epithelium as observed after efferent ductule ligation.

Abstract: Seminiferous tubules from testes of normal and efferent ductule ligated mice were examined with the electron microscope. The tubules in the ligated animals were markedly distended and at most stages of the seminiferous cycle the epithelium exhibited a series of circumferentially-oriented ridges. Cross-sectional profiles of these ridges were studied with particular emphasis on the Sertoli cell junctional specializations and their relationship to the germinal cells. In the ligated specimen the basal cytoplasm of the Sertoli cells is highly attenuated, often appearing as a thin process resting on the basement lamina. Where the cytoplasm of one Sertoli cell ends, it meets in apposition with the cytoplasm of an adjoining Sertoli cell, and at these sites, junctional specializations are present. The ridges are comprised of a stalk of apical Sertoli cell cytoplasm, often appearing like an inverted cone, with young spermatids aligned along the lateral surfaces and the more mature spermatid population embedded within the apical cytoplasm. Junctional specializations were observed along these lateral Sertoli cell surfaces. In some instances, they formed a free surface, but usually early spermatids were in contact with the junctional specializations. With respect to the more mature spermatids, the acrosomal component was typically found in relation to a junctional specialization. Germ cells at the spermatocyte stage were also noted in relation to the Sertoli cell junctional specializations. The findings suggest that spermatocytes cross the Sertoli cell barrier and gain access to the adluminal compartment of the seminiferous tubule through the disengagement of the inter-Sertoli cell junctional complex. It is proposed that when the inter-Sertoli cell junctional specializations separate, the spermatocytes come in apposition with the newly freed junctional surfaces and remain in relation with them through the ensuing divisions. It appears that at some point, firm adhesion between germ cells and the junctional specializations occurs; the spermatid progeny may thus maintain contact with the original inter-Sertoli cell junctional specializations until their release into the tubule lumen.

The aglomerular nephron of antarctic teleosts: a light and electron microscopic study.

Abstract: Complete serial sections demonstrated that ten species of Antarctic teleost fishes representing two families had aglomerular kidneys. The aglomerular nephron of such kidneys consists of two distinct regions: (1) a highly contorted principal segment and (2) a system of collecting tubules and ducts. Throughout the principal segment the cells are characterized by densely packed microvilli and a single cilium projecting into the lumen. Within the cytoplasm, lysosomes are rarely encountered, as would be expected if there is little or no reabsorption of protein from the urine. At the base of these cells, the plasma membrane is prominently infolded in close association with abundant mitochondria. The overall fine structure of the principal segment cells is consistent with their probable function in the secretion of ions into the formative urine. Between the principal segment and the collecting tubule is a very short transitional zone characterized by transitional mucus cells and multiciliated cells. The collecting tubule and duct system is lined entirely by mucus cells. In comparison with principal segment cells, the mucus cells have a well-developed Golgi complex and abundant secretory granules in the apical cytoplasm; these granules presumably contain the non-sulfated acid mucopolysaccharide demonstrable by light microscopic histochemistry

The fine structure of the fundic stomach epithelium of the western newt (Triturus torosus) I. Resting, non-stimulated.

Abstract: Summary Triturus torosus has a resting fundic stomach with gastric pits and glands and cell types similar to previously described amphibian species. Lining the surface and the gastric pits are columnar mucus-secreting cells. They differ in morphology and staining reactions from the mucous-neck cells, the second type of mucus-secreting cells. The latter are confined to a limited region at the necks of gastric glands where they empty into the pits and appear to “isolate” the main oxyntic, acid-secreting cells from the surface mucous cells. The gastric glands are lined by a single cell type, the oxyntic cell, which shows features of both the mammalian chief (zymogenic) and parietal (oxyntic) cells and which presumably secretes both enzymes and acid. This cell has a prominent granular endoplasmic reticulum with prezymogen and zymogen granules, numerous mitochondria, and in the apical cytoplasm an extensive system of tubules and tubulovesicles. The membrane bounding these tubules appears identical to the surface plasmalemma, and occasional continuity between the two can be demonstrated. The oxyntic cells have also a few apical microvilli and intercellular but not intracellular canaliculi. Occasional argentaffin or enterochromaffin cells with few granules are scattered among the oxyntic cells. Like other amphibia, the western newt feeds intermittently and thus is a good experimental animal for the study of gastric secretion. Zusammenfassung Feinstruktur des Epithels des Magenfundus beim “Western” Molch (Triturus torosus) 1. Normalstatus Der normale Magenfundus bei Triturus torosus hat Grubchen, Drusen Zelltypen gleich denen fruher beschriebener Amphibienarten. Das Oberflachenepithel der Grubchen ist hochprismatisch und schleimsezernierend; es weicht formal und farberisch von der mukosen Halszelle als zweitem schileimzernierendem Zelltyp ab. Letzterer kommt nur in bestimmten Halsabschnitten der Drusen vor; er entleert sich in die Grubchen und scheint die sauresezernierenden Belegzellen von den oberflachlichen mukosen Zellen zu separieren. Auf die Halszellen folgen Belegzellen als einziger Zelltyp, der jedoch Eigentumlichkeiten sowohl der Hauptzellen als auch der Belegzellen der Sauger zeigt und wahrscheinlich sowohl Enzyme als auch Saure sezerniert. Er hat ein ausgepragtes rauhes endoplasmatisches Retikulum mit Prazymogenund Zymogengranula; zahlreiche Mitochondrien und, apikal, massenhaft Tubuli und Tubulovesikel. Die Grenzmembran dieser Tubuli gleicht dem Zytolemm; beide gehen gelegentlich ineinander uber. Die Belegzellen besitzen apikal auch einige Microvilli sowie interzellulare (nicht intrazellulare) Kanalchen. Argentaffine oder enterochromaffine Zellen mit wenig Granula sind gelegentlich zwischen den Belegzellen vorhanden. Gleich anderen Amphibien nimmt diese Molch-Art periodisch Nahrung zu sich, so das sie sich als Versuchstier uber das Studium der Magensekretion gut eignet. Resume La Structure de L'epithelium Fundique de L' estomac du Triton (Triturus torosus) 1: Au repos, sans stimulation Au repos, la muqueuse fundique de l'estomac de Triturus torosus preesente les memes cryptes, glandes et types cellulaires que ceux decrits anterieurement chez les Amphibiens. Le revetement de la surface et des crypts gastriques est forme de cellules cylindriques a mucus. Leurs formes et leurs reactions tinctoriales different de celles des cellules a mucus des cols glandulaires, lesquels constituent un second type de cellules a mucus. Ces dernieres sont limitees a un etroite region du col des glandes gastriques, par lequel elles deversent leurs produits dans les cryptes; elles semblent isoler les cellules oxyntiques des cellules a mucus de la surface. Les glandes gastriques sont tapissees par un type unique de cellules, dont les caracteres evoquent a lafois ceux des glandulocytes principaux et des glandulocytes parietaux des Mammiferes et qui secretent probablement a la fois les enzymes et l'acide chlorhydrique. Ces cellules ont un reticulum endoplasmique granuleux, avec des grains de prezymogeene et de zymogene, de nombreuses mitochondries et dans le cytoplasme apical, un systeme important de tubules et de tubulovesicules. La membrane qui limite ces tubules semble identique au plasmalemme superficiel et une continuite peut etre parfois rencontree entre les deux. Les cellules oxyntiques ont aussi quelques microvillosites apicales et intercellulaires mais n'ont pas de canalicules intracellulaires. On trouve de temps en temps quelques cellules argentaffines ou enterochromaffines pourvues en granules, disseminees parmi les cellules oxyntiques. Comme les autres amphibiens, Triturusto rosus se nourrit de facon intermittente et par consequent est un excellent animal d'experience pour l'etude de la secretion gastrique. Resumen Ultraestructura del epitelio en el fondo gastrico de la salamandra «del oeste» (Triturus torosus) 1: Hallazgos normales El fondo gastrico normal de Triturus torosus presenta foveolas, glandulas y tipos celulares iguales a los descritos en otras especies de anfibios. El epitelio superficial de las foveolas es prismatico alto y tiene secrecion mucosa; se distingue morfologicamente y en su coloracion del otro tipo de celulas de secrecion mucosa, representado por las celulas mucosas del cuello. Este ultimo se encuetra solo en ciertas regiones del cuello de las glandulas; vierte su secreto a las foveolas y parece separar las celulas mucosas de la superficie de las celulas de revestimiento que segregan sustancias acidas. A las celulas del cuello siguen las celulas de revestimiento como unico tipo celular, que reune las characteristicas de las celulas principales y de revestimiento de los mamiferos, segregando probablemente acido y encimas a la vez. Presenta un reticulo endoplasmatico bien desarrollado con granulos precimogenos y cimogenos; mitocondrias numerosas y abundantes tubulos y tubulovesiculas en la region apical. La membrana limitante de estos tubulos se asemeja al citolema; ambos se continuan a veces entre si. Las ceelulas de revestimiento presentan microvellosidades apicales y canaliculos intercelulares (no intracelulares). Entre las celulas de revestimiento, a veces se encuentran celulas argentafines o enterocromafines con muy poca granulacion. De manera analoga a otros anfibios, tambien esta salamandra ingiere sus alimentos periodicamente. Por eso puede considerarse como un animal muy util para estudios de la secrecion gastrica.