Showing papers on "Apical cytoplasm published in 1970"

The fine structure of the digestive tubules of the Marine Bivalve Cardium edule.

Abstract: The epithelium lining the digestive tubules of Cardium edule consists of three cell types, namely mature digestive cells, mature secretory cells and immature flagellated cells. Both the secretory and flagellated cells exhibit a pronounced basiphilia and occur in well-defined crypts. The secretory cells are pyramidal in shape and characterized by the possession of a well-developed granular endoplasmic reticulum and Golgi apparatus. Golgi vesicles derived from the latter migrate to the apical region of the cell where they release their contents into the lumen of the tubules. It is possible that the secretion contains enzymes and although it is likely that such enzymes would function primarily in the lumen of the tubules they may also be the source of the weak proteolytic activity which has been recorded in the gastric fluid of many bivalves. The immature flagellated cells are columnar in shape and possess a poorly developed endoplasmic reticulum and numerous free ribosomes. Although no evidence for this was obtained it is suggested that they may serve to replace either or both of the mature cell types. The digestive cells vary from cuboidal to columnar, possess distinctive Golgi elements with characteristic intracisternal membranous elements, and are capable of ingesting exogenous material from the lumen of the tubule. The process of ingestion was examined following feeding experiments with (a) a mixture of iron oxide and colloidal graphite (Aquadag), (b) whole blood from pigeon and (c) ferritin. Individual particles of graphite were enclosed in phagosomes by a process of phagocytosis, while the proteins haemoglobin and ferritin were ingested by a process of pinocytosis; the membrane enclosing the pinocytic vesicles possesses a characteristic outer granular coat. The contents of both the phagocytic and pinocytic vesicles were transferred to larger bodies considered to be primarily phagosomes in the sub-apical regions of the cell. These possess an interconnecting system of membrane-bound channels which ramifies through the apical cytoplasm. Phagolysosomes deeper in the cytoplasm of the cell were identified by the presence of exogenous material and a positive reaction to tests for acid phosphatase activity. They showed changes in appearance which could be put into a series suggestive of the progressive intracellular digestion of the ingested material.

Ultrastructure of human labial salivary glands. III. Myoepithelium and ducts

Abstract: Myoepithelial cells were present between the basal lamina and the acinar secretory cells of human labial salivary glands. In form and disposition, they resembled myoepithelial cells in the major salivary glands. Many of these cells possessed single cilia on their upper surfaces. Such cilia occasionally extended into invaginations of the overlying secretory cell. The intercalated ducts were variable in occurrence. Their epithelium ranged from columnar to squamous, and showed few signs of secretory activity. Few intralobular ducts possessed basal striations. While mitochondria were abundant in non-striated cells, they were randomly disposed in both basal and apical cytoplasm, and the basal plasmalemma showed only occasional infoldings. The paucity of true striated ducts in labial salivary glands may be responsible for the high concentration of sodium and chloride in unstimulated labial gland salivary secretions.

The fine structure of von ebner's gland of the rat

Abstract: The fine structure of von Ebner's gland was studied in untreated rats and rats stimulated to secrete by fasting-refeeding or injection of pilocarpine. Cytological features were similar to those reported for pancreas and parotid gland. Abundant granular endoplasmic reticulum filled the basal portion of the cell, a well-developed Golgi complex was located in the vicinity of the nucleus, and the apical portion of the cell was filled with dense secretory granules. Dense heterogeneous bodies resembling lysosomes were closely associated with the Golgi complex. Coated vesicles were seen in the Golgi region and also in continuity with the cell membrane. Granule discharge occurred by fusion of the granule membrane with the cell membrane at the secretory surface. Successive fusion of adjacent granules to the previously fused granule formed a connected string of granules in the apical cytoplasm. Myoepithelial cells were present within the basement membrane, and nerve processes were seen adjacent to acinar and myoepithelial cells. Duct cells resembled the intercalated duct cells of the major salivary glands.

The fine structure of the guinea pig visceral yolk sac placenta

Abstract: The structure of the guinea pig visceral yolk sac from 26 days of gestation to term was studied by transmission and scanning electron microscopy. Particular emphasis was placed on the columnar endoderm cells of the villous portion of the yolk sac. The apical cytoplasm of the endoderm cells contained numerous membrane invaginations, endocytic vesicles, dense tubules and large vacuoles which appeared to form an interrelated absorptive system. The saccular invaginations of the apical cell membrane were specialized by the development of both an amorphous extracellular coat and an internal coat. Both the endocytic vesicles and dense tubules were thought to be derived from the saccular invaginations following detachment of the latter from the cell surface — the endocytic vesicles forming by fusion of saccules creating progressively larger structures, and the dense apical tubules forming by a process involving fluid loss from the saccules. Large vacuoles were present deeper in the apical cytoplasm; these probably were formed by fusion of smaller vesicles. The supranuclear cytoplasm contained numerous dense droplets and a Golgi zone. The possible relationships of the droplets to the vacuoles was discussed.

The Endocrine Cells in the Human Pyloric Antrum. An Electron Microscope Study of Biopsy Materials

Abstract: The mucosa of the pyloric antrum was taken by biopsy from seven patients under a direct inspection with a fiber-gastroscope and studied by electron microscopy. At least four types of basal-granulated cells were found in the deeper layer of the antral mucosa:1. Enterochromaffin cells were fewer than in the human duodenum. A possible subtype with vacuolated granules was found.2. G cells with rounded cell body and partly vacuolated basal granules were the most numerous and were considered to be the source of gastrin.3. Endocrine cells of a third type were characterized by spotted distribution of basal granules of dense and small type and abundant cytoplasmic filaments.4. Cells tentatively called gastric D-like cells because of their morphologic resemblance to the pancreatic D cells and duodenal D-like cells were found though less frequently than in the duodenum. A possible secretion of secretin from D type cells was discussed.5. In all the types of basal-granulated cells, a narrowed apical cytoplasm was extended to the epithelial surface and provided with microvilli projecting into the lumen. A hypothesis of unicellular feedback mechanism in the secretion of gastrin and other antral hormones was proposed on the basis of this fine structure of basal-granulated cells.

On the fine structure of the aglomerular renal tubule in Lophius piscatorius

Abstract: The fine structure of the secretory tubules in the kidney of the aglomerular goose-fish (Lophius piscatorius) is described. The cells have a pyramidal shape, are joined together by multiple desmosomes, and share as main characteristics: abundant and deep inflections of the basal and lateral cell membranes; “coated” luminal plasma membranes forming multiple microvilli or a genuine brush border; moderate numbers of comparatively small mitochondria, usually unassociated with the basal and lateral plasma membrane specializations; numerous multivesicular bodies occuring in the apical cytoplasm; abundant large lysosome-like bodies in the intermediate regions of the cytoplasm; and comparatively poor development of endoplasmic reticulum and Golgi apparatus.

Functional morphology of the digestive tract epithelium in Phoronis vancouverensis (Pixell): an ultrastructural and histochemical study.

Abstract: The ultrastructure of the gut regions of the marine filter-feeder Phoronis vancouverensis was correlated with enzyme activity as revealed histochemically. The oesophagus, proventriculus, and stomach epithlia showed intense esterase and acid and alkaline phosphatase activity. The staining reaction was confined primarily to small globules in the apical cytoplasm of the epithlial cells. Electron micrographs of the same regions showed a high incidence of zymogenlike granules, with a corresponding abundance of ribosomes and of rough endoplasmic reticulum. Also, the proventricular and to a lesser extent the stomach epithelia were found to contain a large number of lipid bodies. This was confirmed with positive Sudan IV staining for fats. The intestinal region of the gut was found devoid of esterase and phosphatase activity. The epithelial surface in this region was found elaborated into microvilli. The entire gut is ci iated. A new paired-cilium apparatus is described in this phylum. From these findings Phoronis vancouverensis is concluded to be suitably adapted to its continuous filter-feeding existence, with the anterior gut epithelia synthesizing hydrolytic enzymes for release into the lumina of the proventriculus and stomach. Subsequently, in the hindgut the products of initial extra-cellular digestion are absorbed via the microvilli and treated intracellularly within the intestinal epithelium. The proventriculus is further thought to function in lipid absorption and storage. The presence of chromaffin-like granules observed in some proventricular and intestinal epithelial cells suggests that digestion in this phylum may in part be under neurosecretory control.

Localization of diamine oxidase and d-amino acid oxidase in kidney, demonstrated by means of immunohistochemical method

Abstract: The localization of both diamine oxidase and D-amino acid oxidase was examined by immunofluorescent technique on the frozen section of the porcine kidneyThe cells, composing the Bowman's capsule and the proximal convoluted tubule, showed intense fluorescence which showed the localization of diamine oxidase The antigen was concentrated in the supra- and para-nuclear cytoplasm But, unlike monoamine oxidase, diamine oxidase may not be located in the mitochondria, because higher concentration of diamine oxidase is found in the apical cytoplasm where the mitochondria are not so much observedThe D-amino acid oxidase was demonstrated in the apical cytoplasm of the cells constituting the Bowman's capsule, the proximal convoluted tubule and a part of the Henle's loopThe place where two enzymes were located was, as mentioned above, mostly in the proximal convoluted tubule At this place, the large amount of ammonia was reported to be secreted and the highest activity of the two enzymes was also encountered In other words, the location of two enzyme proteins, the place where ammonia is eliminated and the sites of enzymatic activity of two enzymes were quite identical