Showing papers on "Apical cytoplasm published in 1967"

Functions of coated vesicles during protein absorption in the rat vas deferens

Abstract: The role of coated vesicles during the absorption of horseradish peroxidase was investigated in the epithelium of the rat vas deferens by electron microscopy and cytochemistry. Peroxidase was introduced into the vas lumen in vivo. Tissue was excised at selected intervals, fixed in formaldehyde-glutaraldehyde, sectioned without freezing, incubated in Karnovsky's medium, postfixed in OsO(4), and processed for electron microscopy. Some controls and peroxidase-perfused specimens were incubated with TPP,(1) GP, and CMP. Attention was focused on the Golgi complex, apical multivesicular bodies, and two populations of coated vesicles; large (> 1000 A) ones concentrated in the apical cytoplasm and small (<750 A) ones found primarily in the Golgi region. 10 min after peroxidase injection, the tracer is found adhering to the surface plasmalemma, concentrated in bristle-coated invaginations, and within large coated vesicles. After 20-45 min, it is present in large smooth vesicles, apical multivesicular bodies, and dense bodies. Peroxidase is not seen in small coated vesicles at any interval. Counts of small coated vesicles reveal that during peroxidase absorption they first increase in number in the Golgi region and later, in the apical cytoplasm. In both control and peroxidase-perfused specimens incubated with TPP, reaction product is seen in several Golgi cisternae and in small coated vesicles in the Golgi region. With GP, reaction product is seen in one to two Golgi cisternae, multivesicular bodies, dense bodies, and small coated vesicles present in the Golgi region or near multivesicular bodies. The results demonstrate that (a) this epithelium functions in the absorption of protein from the duct lumen, (b) large coated vesicles serve as heterophagosomes to transport absorbed protein to lysosomes, and (c) some small coated vesicles serve as primary lysosomes to transport hydrolytic enzymes from the Golgi complex to multivesicular bodies.

INTESTINAL TRIGLYCERIDE ABSORPTION IN THE RAT : An Electron Microscopical Study

Abstract: This report provides information on the morphology of fat absorption in rat intestinal epithelial cells. Three types of experiments were performed: (a) intubation of corn oil into fasted rats, (b) injection of physiological fatty-chyme prepared from fat-fed donor rats into ligated segments of jejunum of fasted animals, and (c) administration of electron-opaque particles in corn oil and markers given concurrently with the fat. These results support the hypothesis that fat is absorbed by selective diffusion of monoglycerides and fatty acids from micelles rather than by pinocytosis of unhydrolized triglycerides. Evidence is presented that the pits between the microvilli, previously believed to function in the transport of fat, are not involved in this process. Instead they appear to contribute their contents to lysosomes in the apical cytoplasm. Arguments are offered that the monoglycerides and fatty acids diffuse from the micelle while the latter is associated with the microvillous membrane of the absorptive cell. These micellar components penetrate the plasma membrane and diffuse into the cytoplasmic matrix where they encounter the SER. Triglyceride synthesis occurs in the SER and results in the deposition of fat droplets within its lumina. The synthesis of triglycerides and their sequestration into the SER establishes an inward diffusion gradient of monoglycerides and fatty acids.

Coated vesicles in absorptive cells of Hydra.

Abstract: The apical cytoplasm of absorptive cells in hydra gastroderm contains numerous vesicles having a discoidal shape, an asymmetrical membrane and a peculiar coat firmly attached to the luminal surface of the membrane. The coat of these ‘discoidal coated vesicles’ consists of a highly ordered array of subunits made up of ‘pegs’ and globules. That these vesicles are involved in selective absorption and transport of materials from the gastrovascular cavity can be seen readily using ferritin as tracer. They are also involved in the uptake of particulate glycogen and the phagocytosis and possibly the subsequent digestion of complex food droplets. It may reasonably be supposed that the array of the coat subunits indicates a similar array of the molecular constituents of the membrane to which it is attached. In tangential sections of the membrane a compressed hexagonal lattice is seen which could fit the coat array.

Some new cytological observations of the normal rat ependymal cell.

Abstract: The ependyma of the lateral ventricle of normal adult rats fixed by intravascular perfusion with either glutaraldehyde or formaldehyde was examined with the electron microscope. Three main observations of the normal ependymal cells were made which, to our knowledge, have not yet been reported. 1 Ependymal cells were occasionally found directly abutting on blood vessels in the immediate vicinity. In this respect, they were very much like the well-known perivascular astrocytes and tanycytes. This similarity was strengthened by the morphological details of the junctional areas. 2 Bundles of the fine fibrils (app. 60 A) were seen in the nuclei. They were devoid of any membranous boundary and were apparently identical to the fibrils often seen in the perinuclear cytoplasm. 3 Microtubules, occasionally containing approximately 50 A central densities, were consistently seen in the apical cytoplasm. They were apparently identical to the familiar microtubules constituting the cillary fine structure which also contained occasional central densities.

The mechanism of spermiation in the toad

Abstract: The present paper is the first demonstration, at the ultrastructural level, of the mechanism of sperm release from the Sertoli cells. The main target of the immediate effect of LH is the cytoplasm of the Sertoli cells. Three main stages are recognized in the cellular response: (1) swelling of the endoplasmic reticulum, (2) swelling of the apical cytoplasm, (3) the apical detachment. The preservation of the nucleated basal portion of the Sertoli cells after the stage of apical detachment is assured by a mechanism of protective overlapping of residual membranes. It has also been shown that LH is able to increase water and sodium content in the toad testis. It is postulated that water enters after the injection of the LH into the channels of the endoplasmic reticulum, then the water moves into the apical cytoplasm attracted by hydrophilic products derived from enzymatic splitting of cytoplasmic mucoproteins. Finally water passes into the lumen of the seminiferous tubules simultaneously with cell debris and the liberated spermatozoa. The lysosomes present in the cytoplasm of the Sertoli cell in this mucolytic action may be involved.

Electron microscopic and histochemical identification of lipofuscin in the human inner ear.

Abstract: Normal inner ears of 14 individuals ranging from 2 days to 91 years of age were studied with electron microscopic and histochemical techniques for the distribution of lipofuscin and lysosomal enzymes (acid phosphatase, beta-glucuronidase and N-acetyl-beta-glucosaminidase). The electron microscope revealed in the cochlea large membrane-limited inclusions in the apical cytoplasm of all epithelial cells lining the endolymphatic space. Similar inclusions were also seen in the vestibular apparatus; the apical zone of the sensory and supporting cells, as well as the transitional epithelium and dark cells contained numerous lipofuscin granules. In the same locations where these structures occurred, we have observed intracytoplasmic granules with the histochemical characteristics of lipofuscin, including yellow to green autofluorescence. The sites of lipofuscin accumulation also displayed strong acid phosphatase activity. Lipofuscin could not be demonstrated histochemically in the newborn and was only sparse in c...

Fine structure of the cytoplasm in salivary glands of Simulium.

Abstract: SUMMARY The salivary glands of 3rd or 4th instar larvae of Simulium niditifrons are about 5 mm long and up to 400 fi wide. They have a capacious lumen which is normally filled with secretion. The apical (luminal) plasmalemma of the gland cells is thrown into numerous microvilli. The basal plasmalemma is usually straight but is infolded in places. The infoldings may be complex near to cell junctions. There is a thick, uniform basement membrane. Contact surfaces of adjacent cells often interdigitate. A septate junction extends inwards from the lumen for onequarter the depth of the cells. Rough endoplasmic reticulum is distributed evenly throughout the cytoplasm. Many Golgi complexes with dark membrane-bounded granules are scattered throughout the cytoplasm. Solitary granules, often more than 1 fi in diameter, lie in the apical cytoplasm, especially near the apical border of the cell. These granules resemble the larger Golgi granules and the contents of the lumen. Solitary granules consisting of 2 components have been seen in various stages of passage through the cell membrane. The 2 components are present in roughly constant proportions and can be identified in the larger Golgi granules and in the secretion in the lumen. The nucleus is spherical. The nuclear envelope is smooth in the larger cells of a gland but may be folded in the smaller cells. There are 80-100 pores//* 2 of nuclear envelope. Each pore appears to have a small granule at its centre. Microtubules, about 180 A thick, are numerous in the apical cytoplasm, particularly near the luminal border. Tubules which lie deep in the cytoplasm are flanked by a clear area 100—200 A wide. The fine structure of a salivary gland cell of Simulium appears to indicate that the major components of the salivary secretion are synthesized in association with the ribosomes on the rough endoplasmic reticulum, concentrated in the Golgi regions, formed into secretion granules, and passed out of the cell into the lumen of the gland by reverse phagocytosis.

Observations on the ultrastructure of the developing cerebellum of the Macaca mulatta.

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.

Fine structure of the striated border of the intestinal cells of Ancylostoma caninum.

Abstract: The striated border of the intestinal cells is composed of numerous microvilli. The terminal web is separated from the apical surface of the intestinal cell by a cytoplasmic layer. This layer is joined with the main body of cytoplasm beneath the terminal web by many connections which perforate the latter. However, the apical layer is devoid of fibrous elements, mitochondria, and pigment granules found in the cytoplasm proper. The terminal web is densely homogeneous and has extensions upwards through the apical cytoplasm into the microvilli forming a dense cytoplasmic core in each. The web extends some distance down the lateral plasma membranes forming a perforated cap over the main cytoplasmic mass of the intestinal cell. This type of terminal web has not been described in other nematodes. Browne and Chowdhury (1959) concluded from electron microscopy that the intestinal lumen of Ancylostoma caninum was lined with true cilia. In a later study Browne, Chowdhury, and Lipscomb (1965) modified that conclusion and stated that the structures were suggestive of cilia but that inadequate fixation prevented a specific determination. In the present study the structure of the luminal area of the intestinal cell of A. caninum was clarified by the use of modern techniques of fixation and embedding. MATERIALS AND METHODS Adult A. caninum were obtained from experimentally infected dogs. Each worm was placed in ice-cold 4% glutaraldehyde in phosphate buffer (Pease, 1964). A transverse slice, 1 mm long, was cut just posterior to the esophagus and placed in fresh ice-cold fixative for 1 hr. The tissue was then removed and washed in phosphate buffer without additives (Millonig, 1961, 1962) for 16 hr at 8 C. Postfixation was with ice-cold 1% osmium tetroxide in phosphate buffer (Millonig, 1961, 1962) for 1 hr. Dehydration was by means of an ethanol series with two 15-min washes in propylene oxide. The tissue was infiltrated with a mixture of equal parts of propylene oxide and Araldite 502 mixture (Luft, 1961) for 16 hr at 25 C, followed Received for publication 6 May 1966. * This investigation was supported by Public Health Service Research Grant AI-02347 from the NIAID of the NIH. by several rinses of 2 hr each in Araldite 502 mixture. Polymerization was accomplished in a third change at 60 C for 24 hr. Thin sections were cut with glass knives using an LKB Ultratome and were picked up on naked 400-mesh copper grids. Contrast was enhanced by staining 20 min with each of two solutions, 1.5% uranyl acetate and lead citrate (Reynolds, 1963). Sections were examined and photographed at 50 kv in a Hitachi HU 11A electron microscope with initial magnifications up to 50,000 X.

Fine structure of the functional mesonephros in the eight-day chick embryo.

Abstract: An electron microscopic study of the functional mesonephros in the 8-day chick embryo revealed the following features of the nephron: Proximal tubule cells. Nuclei are spherical and basally oriented. Mitochondri are round or elongate with clear-cut cristae. Intramitochondrial granules occur sporadically. The Golgi complex, lying adjacent to the nucleus in apical cytoplasm, consists of flattened lamellae and associated secretion droplets. The cytoplasm is filled with ribosomes which occasionally are spiral in arrangement. Characteristic microvilli project from the apical end of cells. Basal regions of the cells are bounded by a homogeneous basement membrane. Adjacent epithelial cells are separated at their base by wide intercellular spaces. Interdigitating processes between cells are common in this area. At their apices, cells are joined by junctional complexes. Distal tubule cells. Nuclei are round and centrally located. Microvilli are sparse and usually absent. When present, they are short and blunt. Cells are closely allied at their base and joined tightly at their apices. Interdigitating processes are not as prevalent as in proximal tubules. Infoldings of the plasma membrane are prominent and compartmentalize mitochondria. Glomerulus. Endothelial cells are elongate, bordering the capillary lumen, and their membranes contain definite slit-pores. Epithelial pedicels extend from the cell body, intergiditate with each other and rest on the capillary basement membrane. The latter consists of three layers resembling those in adults. The similarity in the fine structural characteristics between chick mesonephros and adult metanepros corroborates the holonephric theory of vertebrate kidney evolution.

The effects of ovarian hormones on uterine phosphatases of the rhesus monkey (Macaca Mulatta)

Abstract: Endometrial acid and alkaline phosphatases were studied histochemically in rhesus monkeys treated with various combinations of estrogen (E, 17β-estradiol and/or estriol), progesterone (P) and relaxin (R) or a low potent relaxin control preparation (NRF). In the cells of the uterine glands of the E-treated animal, the apical cytoplasm showed intense activity of both phosphatases. This estrogenic response was depressed in the stratum functionale by P and in the stratum basale by PR. With E, acid phosphatase-staining granules appeared in scattered stromal cells with eccentric nuclei. Addition of P or PR increased the number of acid phosphatase positive stromal cells, especially in the stratum functionale. With the exception of the sinus-like channels and superficial vessels of the stratum functionale of monkeys treated with ER and EPR, all endothelium of capillary and precapillary vessels was rich in alkaline phosphatase activity. Thus, acid alkaline phosphatases appear to be metabolically important components of the endometrium which undergo cyclic variation and reflect specific influences of the ovarian hormones; estrogens, progesterone and relaxin. The implications to human menstrual physiology are discussed.

Fine structure of ureteric duct epithelium in the North Atlantic hagfish (Myxine glutinosa L.).

Abstract: The epithelial cells lining the ureteric duct in the cyclostome, Myxine glutinosa, have a brush border and show specializations of their apical cytoplasm similar to those observed in absorptive proximal tubule cells in higher vertebrate species. These features and the presence of large and numerous cytosomes, presumed to contain lysosomal enzymes, indicate that the ureteric epithelium has taken over some of the functions of the proximal tubule in the “atubular” kidney of Myxine.

Evaluation of microscopic methods in the diagnosis of idiopathic steatorrhoea

Abstract: Of 14 cases of clinically and biochemically confirmed idiopathic steatorrhoea, 11 showed mucosal abnormalities when biopsy specimens from the upper small intestine were examined under the dissecting, the light, and the electron microscope. In the three remaining cases mucosal changes could be detected only under the electron microscope. The simple and inexpensive dissecting microscope can therefore be accepted as an efficient instrument for routine use in the diagnosis of idiopathic steatorrhoea and for the screening of cases which might merit further examination under the electron microscope. The light microscope allows the heights of the villi and the depth of the glandular layer to be measured and the limits of normality to be defined on a quantitative basis. The electron microscope reveals abnormalities in the microvilli of mucosal epithelial cells. The mildest changes consist of shortening and fusion of the microvilli and a lessened electron-density of the apical cytoplasm. Since these changes occur in mucosae which appear to be normal under the dissecting and the light microscope they are assumed to be related to the earlier stages of the disease and their significance is discussed in the light of this view.

Electron microscopic observation on the effect of actinomycete Streptomyces punicens (viomycin) in the vestibular apparatus

Abstract: This experiment was performed as a part of the series of the electron microscopic studies on vestibular apparatus.(1) The cells of ampullae of the labyrinth which were damaged with Viomycin in various doses were revealed electron microscopically.(2) The cell surface and the apical cytoplasm of ampullae of the labyrinth were damaged.(3) The dense body and multivesicular body extremely resembling lysosome were observed.(4) There was evidence morphologically that the onset of cell damage by Viomycin seemed to begin at the cell surface such as effect of Strepto. mycin or Kanamycin.