Showing papers on "Apical cytoplasm published in 1982"

Carbonic anhydrase histochemistry in rabbit and mouse kidneys.

Abstract: The presence of carbonic anhydrase activity in rabbit and mouse kidneys was examined using a histochemical procedure with plastic embedded sections stained by the modified version of the cobalt-phosphate method (Hansson, 1967, 1968; Ridderstrale, 1976). Proximal convoluted tubules (S1 and S2 segments) in both species were strongly positive for carbonic anhydrase activity on the membranes of the luminal, lateral, and basal surfaces. The apical cytoplasm beneath the brush border and the nuclei also stained positively for carbonic anhydrase. The S3 segment (pars recta) of the proximal tubule in the rabbit was positive on the luminal membrane, with somewhat less intensity seen on the lateral and basal surfaces. This segment in the mouse was completely negative. The first part of the thin limbs of long-looped nephrons exhibited strong staining in the mouse. Faint luminal staining was present on descending thin limbs of short-looped nephrons in the mouse. In the rabbit, both the medullary and cortical ascending thick segments of the limb of Henle were completely negative. In contrast, the medullary and cortical ascending thick limbs in the mouse kidney showed staining on all plasma membranes. The intercalated cells in the cortical and medullary portion of the collecting tubules stained positively for carbonic anhydrase in both species. The principal cells of the collecting duct in the cortex were negative in the rabbit and faintly positive in the mouse. The principal cells in the upper medullary collecting tubules in both species stained intensely along the luminal, lateral, and basal cell membranes. The papillary collecting ducts were largely negative in both the rabbit and the mouse. Some interstitial cells in the rabbit in the region of the papillary tip were strongly positive. We conclude that there is a marked difference in carbonic anhydrase activity within and between the renal tubular segments of the rabbit and the mouse. In addition, these distinct differences that exist between the two species correlated with known physiological roles in ion transport.

Absence of myosin-like immunoreactivity in stereocilia of cochlear hair cells.

Abstract: Movements of the stiff sensory hairs, the stereocilia, which extend outwards from the apical surface of the hair cells in the auditory organ, are thought to have a key role in the process of transduction of sound energy into electrical impulses. Each stereocilium is supported by a paracrystalline axial bundle of actin filaments, which have identical polarities and are extensively cross-linked1–4. Recent immunohistochemical observations on whole mounts of the guinea pig organ of Corti indicated myosin-like immunoreactivity in association with hair cell stereocilia5. Considering the steric situation, it is, however, difficult to imagine any functional interaction between the bundled actin filaments and the assumed myosin molecules. Here we report that in semi-thin, transverse sections of quick-frozen, freeze-dried and plastic-embedded guinea pig organ of Corti, myosin-like immunostaining was restricted to the apical cytoplasm of hair cells and was not detected along the stereocilia. With respect to the immunohistochemical distribution of actin, myosin and the muscular Z-line protein, α-actinin, the apex of hair cells strongly resembles the intestinal epithelial brush border6–7.

Endocytic pathways at the lateral and basal cell surfaces of exocrine acinar cells.

Abstract: In parotid acinar cells, horseradish peroxidase (HRP) administered via the main excretory duct is endocytosed from the apical cell surface in smooth C- or ring-shaped vesicles (Oliver, C. and A. R. Hand. 1979. J. Cell Biol. 76:207). These vesicles ultimately fuse with lysosomes adjacent to the Golgi apparatus. The present investigation extends these findings and examines the uptake and fate of intravenously injected HRP from the lateral and basal cell surfaces of resting and stimulated parotid and pancreatic acinar cells from rats and mice. Isoproterenol and pilocarpine were used to stimulate the parotid gland and the pancreas, respectively. HRP was internalized in smooth and coated vesicles primarily in areas of membrane infoldings. Both the number of coated vesicles and the amount of tracer internalized increased markedly following secretagogue administration. In both resting and stimulated cells, the HRP was rapidly sequestered in a unique system of basally located lysosomes that possess trimetaphosphatase activity, but not acid phosphatase activity. At 1-3 h after HRP administration, reaction product was also found in multivesicular bodies, vesicles, and lysosomes adjacent to the Golgi apparatus. With time, more HRP was localized in Golgi-associated lysosomes. By 6-7 h, tubules in the apical cytoplasm of stimulated cells contained HRP reaction product. When native ferritin was administered retrogradely and HRP injected intravenously, both tracers could be localized in the same lysosome after 4-5 h, indicating that material taken in from all cell surfaces mixes in Golgi-associated lysosomes. The results of this study suggest that two separate and distinct endocytic pathways exist in exocrine acinar cells: one involves membrane retrieval from the apical cell surface; and the other is a stimulation-dependent process at the lateral and basal cell surfaces.

Three-dimensional organization of microtubules and microfilaments of the basal body apparatus of ciliated respiratory epithelium

Abstract: This is a descriptive study showing the three-dimensional interrelationship of cytoskeletal elements at the apex of ciliated cells of rat respiratory epithelium. Tissue specimens were serially thin sectioned in various planes and examined by transmission electron microscopy. Thicker sections were also cut at various angles and analyzed stereoscopically. Other specimens were cleared of soluble molecules by glycerination or Triton-X100 treatment and sectioned as described above. It was found that C microtubules from the triplets of each basal body diverge from the A and B microtubules, run a short distance, and converge at the basal foot. These microtubules or other microtubules arising anew then dispersed deeper into the cytoplasm. The C fibers also interdigitated with other microtubules running perpendicular to them and parallel to the ciliated surface. Ten-nanometer intermediate filaments were organized in parallel sheets between adjacent basal bodies. Sixnanometer actin filaments were distributed throughout the apical cytoplasm. Neighboring basal bodies were linked to one another by microtubules and microfilaments. Basal bodies from each cell appear to be structured for stability, flexibility, and arranged to operate as a single unit.

Fine Structure of the Ampullary Organs of the Bichir Polypterus senegalus Cuvier, 1829 (Pisces: Brachiopterygii) With Some Notes on the Phylogenetic Development of Electroreceptors

Abstract: The ampullary organs of the bichir were examined by light and electron microscopy. Unlike most other ampullary organs, they are exclusively found in the epidermis and are never sunk into the subepidermal connective tissue. The sensory epithelium consists of sensory cells and supporting cells surrounded by mantle cells. The luminal surface of the sensory cell is provided with a cilium surrounded by several microvilli. In the apical cytoplasm are found numerous mitochondria and microtubules. In the basal part of the cell synaptic sheets or synaptic bodies opposite to afferent nerve endings are frequent.

Experimental pancreatitis in the rat. Light and electron microscopical observations on early pancreatic lesions induced by intraductal injection of trypsin, phospholipase A2, lysolecithin and non-ionic detergent.

Abstract: Trypsin, phospholipase A2, lysolecithin or non-ionic detergent polyoxyethylene p-t-octyl phenol solutions were injected into the rat biliopancreatic duct. Histological and ultrastructural changes in the gland were studied 15 min and 3 h after the injections. The rough surfaced endoplasmic reticulum disintegrated in two ways: (1) the endoplasmic reticulum in the cell periphery was vesiculated but ribosomes were well preserved at 15 min, and (2) large, round membranous structures appeared in apical cytoplasm at 3 h. Zymogen granules disintegrated in the second type, which possibly represents autodigestion. Both types of injury lead ultimately to structureless necrosis. Lesions induced by phospholipase A2 and lysolecithin were identical. Trypsin-induced damage developed slowly and the two phases of endoplasmic reticulum disintegration were not sharply separable. Lesions caused by polyoxyethylene p-t-octyl phenol were variable at 15 min, but at 3 h the type 2 injury described above was observed. It was concluded that although the initial damage in pancreatic acinar cells may vary, necrotic changes are similar despite the injected material at the later time interval. During acute pancreatitis, the acinar cell necrosis is most probably due to the action of lysolecithin produced by the activation of phospholipase A2.

Formation of membrane-bounded secretory granules in the midgut epithelium of a termite, Cubitermes severus , and a possible intercellular route of discharge

Abstract: Mature columnar cells of the midgut of Cubitermes contain a prominent secretion product observed at light- and electron-microscopic levels. At the ultrastructural level the product is resolved as an electron dense material contained in vesicles up to 1 μm diameter that accumulate in the apical cytoplasm. The vesicles are composite, apparently formed by coalescence of at least two types of precursor vesicle both of which originate from the Golgi apparatus. Discharge of the product takes place by exocytosis into intercellular space at or in the vicinity of the apical septate junction complex. Augmentation of apical surface area by microvilli is less prominent in Cubitermes than in other termites for which data are available. This and other evidence suggests that absorptive functions are reduced in the midgut of this insect.

Ultrastructure of the perfused rat epididymis: effect of luminal sodium ion concentration.

Abstract: The appearance of the rat epididymal epithelium changed when it was perfused in vivo through the lumen with unphysiologically high sodium ion concentrations; dilatation of intercellular spaces (ICS) at threshold concentrations of 30mM-Na+ in the cauda and about 55mM-Na+ in the corpus was associated with absorption of water from the lumen. Despite the distended ICS, junctional complexes appeared intact, and their integrity was confirmed by the exclusion of luminal horseradish peroxidase (HRP) from the ICS, and by demonstrating that circulating [3H]inulin did not enter the lumen. Smooth ER and lipid droplets in the principal cells of the corpus epididymidis were well maintained, and the preservation of granular ER in principal cells of the cauda epididymidis lent morphological support to the continued secretion of protein in this segment. However, occasional distension or involution of inner Golgi cisternae was evident in principal cells after 3–6 h perfusion. In contrast to multivesicular bodies of principal cells, the apical and basal vacuoles characteristic of clear cells changed in size with different perfusing solutions. When low Na+ concentrations were perfused large translucent vacuoles were frequently found in the apical cytoplasm of clear cells in the corpus and cauda epididymidis, and filled vacuoles became larger and showed a decrease in content density in the cauda epididymidis. These large vacuoles were absent from tissue perfused with high Na+ concentrations. Normal pinocytotic activity of both cell types was demonstrated by perfusing HRP which was taken up by the normal route in principal cells, with some transfer to the Golgi cisternae. By far the most HRP was accumulated in clear cell vacuoles irrespective of the composition of the perfusing solution.

Preferential uptake of soluble antigen by respiratory tract epithelium overlying bronchus-associated lymphoid tissue in the rat.

Abstract: Soluble protein antigen (Horseradish peroxidase — HRP) administered to rats intratracheally is predominantly phagocytosed by alveolar macrophages and Type-II pneumonocytes. A proportion, after localization on the lumenal surface of the bronchiolar epithelium is transported across the epithelium via the apical cytoplasm and the intercellular space to the region of the basement membrane. The rate of transfer is faster in the epithelium closer to areas of BALT than elsewhere and in these areas there is further significant penetration below the basement membrane into the BALT tissue to facilitate the contact of antigen and of lymphoid cells. No evidence of alveolar macrophage re-entry to the lymphatic system after phagocytosis of HRP could be seen.

Fine Structure of Duvernoy's Gland of the Japanese Colubrid Snake, Rhabdophis tigrinus

Abstract: Duvernoy's gland (a type of venom gland) of the Japanese colubrid snake, Rhabdophis tigrinus, was examined by electron microscopy. The secretory units of the gland consist of the secretory and myoepithelial cells. The secretory cells are columnar in shape and have well-developed rough endoplasmic reticulum (RER), Golgi apparatus and mitochondria in the basal perinuclear cytoplasm. The secretory granules are homogeneous in structure and moderately dense. They are accumulated in the apical cytoplasm and are released by exocytosis into the lumen. The myoepithelial cells often enclose the secretory units, contain bundles of filaments in the cytoplasmic process, and are innervated by the free endings of the autonomic nerves through the basement membrane. In addition, many nerve terminals end in pericapillary spaces, suggesting a release of neurosecretions into the blood. The duct epithelium is composed of typical mucus secreting cells, whose cytoplasm contains secretory globules of lower electron density.

Distribution of transported amino acid within rabbit ileal mucosa.

Abstract: 1 Pieces of rabbit distal ileum, incubated for short periods of time in solutions containing tritiated amino acids, have been processed for autoradiography and the profiles of amino acid concentration across the villi determined by microdensitometry 2 The concentration profiles of a series of amino acids could be described in terms of two descending exponentials, one extending from the brush border to the basal membrane of the enterocyte and the other from the base of the epithelial layer to the centre of the villus 3 Exponential coefficients describing the steepness of these gradients were highest for basic amino acids Coefficients for short-chain amino acids were greater than for long-chain neutral amino acids None of these values changed for times of incubation varying from 5 to 180 sec 4 Enterocytes accumulated amino acids in the apical cytoplasm, against a concentration gradient, within the first few seconds of incubation This step-up in concentration decreased as the external concentration was increased, in a manner dependent on the amino acid used 5 It is suggested that amino acid concentration gradients within enterocytes arise by diffusion and that the amino acid specificity of this process originates from an ability of the more lipophilic amino acids to permeate structures acting as barriers to the more hydrophilic molecules

Electron microscopic observations on single cilia in the intrahepatic biliary ducts in some birds.

Abstract: The intrahepatic biliary passage in five species of birds was investigated with the transmission electron microscope. The avian liver was characterized by a frequent occurrence of intralobular bile ductules and canaliculo-ductular junctions in the parenchyme. It was further characterized by solitary bile ductular epithelial cells intercalated among hapatocytes surrounding bile canaliculi. The present study first revealed that avian bile ductular epithelial cells possess a long single cilium. Its basal body (distal centriole) was connected to a basal foot and slender rootlet and accompanied by a proximal centriole. The hepatocytes facing the bile passage possessed no cilium, although they frequently had a diplosome in their apical cytoplasm. The single cilia of the bile ductular epithelium gradually tapered toward the tip. The original fiber pattern in the most proximal part was peripheral 9 doublets +0. In the ciliary shaft, the doublets altered into singlets which were diminished in number gradually toward the distal parts of the shaft, so that in the tip only one singlet remained. Since these fiber patterns in the single cilia markedly deviated from the 9+2 fiber pattern of the ordinary motile cilia, they may not be motile, but properly regarded as sensory or chemoreceptors.

Ultrastructural changes during stimulation of amphibian oxyntic cells viewed by scanning and transmission electron microscopy

Abstract: Amphibian oxyntic cells exposed by cryofracture were examined by field emission scanning electron microscopy. Comparisons were made between the structure thus revealed and those seen in thin-sectioned material from the same mucosas examined by transmission electron microscopy. Resting oxyntic cells had apical surfaces which were relatively smooth with some short microvilli. Apical cytoplasm was filled with smooth membrane tubules (so-called vesicotubules). Stimulation with a combination of histamine, dibutyryl cyclic AMP, and isobutylmethylxanthine (a phosphodiesterase inhibitor) led to a dramatic elaboration (i.e., increased membrane surface area) and a decrease in number of vesicotubules in the apical cytoplasm. The surface morphology of the stimulated oxyntic cell was much different from that reported for the mammalian parietal cell. Two types of surface elaboration were observed. Most commonly the surface was formed of flattened microplicae or lingulae. An irregular surface formed by the swelling of enlarged spaces near the apical surface was also observed. These new data have been used to evaluate the models which have been proposed to explain the nature of the transition from resting to stimulated morphology. A new model, which incorporates fusion of intracellular vesicotubules with each other and also with apical membrane, is proposed. The proposed fusion process may cause an increase in membrane area open to the extracellular (luminal) solution within the cell (rather than the eversion of membranes into the gastric lumen). Expansion of spaces between the microplicae may be caused by hydroosmotic pressures developed during active HCl secretion.

Demonstration of myoglobin in formalin-fixed renal sections by immunoperoxidase technic.

Abstract: The use of an immunohistochemical technic offers a very sensitive method to detect myoglobin in formalin-fixed, paraffin-embedded tissues. Thus, the technic is suitable for retrospective studies. Myoglobin can be demonstrated at the brush border and apical cytoplasm of the tubular epithelium of proximal tubules. Granular substances and casts in the lumens also react positively with antimyoglobin. Our findings confirm the results of a previous animal study, showing that myoglobin is filtered through glomeruli and reabsorbed by the proximal tubules.

Ultrastructure of the paraphysis cerebri of the water snake Natrix maura L

Abstract: Paraphyseal epithelial cells of Natrix maura have been studied with light and electron microscopy. They showed a clear polarity apically related to the third ventricle and, basally, to a connective tissue layer which surrounded the whole organ. The apical surface of the cells, attached by junctional complexes, showed many microvilli, scarce cilia, and some pinocytotic coated vesicles. In their apical cytoplasm many mitochondria and a well developed Golgi apparatus and endoplasmic reticulum were observed. Whereas lamellar bodies were abundant and closely related with mitochondria, glycogen particles were absent. Basal cell membrane showed infoldings where pinocytotic coated vesicles were detected. In the connective tissue layer, fenestrated sinusoids and fibrocytes, as well as rare unmyelinated nerve fibers engulfed by Schwann cells, were present. The possible active role of paraphyseal cells in exchanging substances between cerebrospinal fluid and blood is discussed.