Mucosal surface morphology of the toad urinary bladder. Scanning electron microscope study of the natriferic and hydro-osmotic response to vasopressin

Abstract

The mucosal cell surface of the toad urinary bladder was examined by scanning electron microscopy, and changes in the structure of the surface of the granular cell were correlated with specific physiological responses to vasopressin. Survey views of the mucosal surface demonstrated that there was no consistent repeating anatomical relationship between the granular cell and the mitochondria-rich cell that would support the concept of cooperativeness in the response to vasopressin. During base-line states of Na+-transport and water flux, the microvilli on the mucosal surface of the granular cell are arranged in a ridge-like network with occasional individual projections. When water flux is increased by exposing the tissue to vasopressin, in the presence of an osmotic gradient across the tissue, the microvilli on the granular cell lose the ridge structure and appear, predominantly, as individual projections. Variability-of this appearance points out the necessity of examining large areas and many samples before the significance of any morphological change can be assessed. Blocking the simultaneously occurring natriferic response of the toad urinary bladder with 10 -2 M ouabain does not prevent these changes in the microvilli. When the hydro-osmotic response is blocked by eliminating the osmotic gradient, the granular cell shows no consistent change in mucosal surface morphology even when fixed at the height of the natriferic response. The mitochondria-rich and mucous cells did not show any change in morphology throughout these studies. We conclude that the changes in the mucosal surface morphology of the toad bladder seen after exposure to vasopressin are a result of the increased water flux that occurs when an osmotic gradient exists across the tissue, and are not related to the natdferic response or any specific alteration in the membrane properties. KEY WORDS toad urinary bladder scanningThe toad urinary bladder has long been used as a electron microscopy vasopressin -granular cell model system for studying the action of the poly- 598J. CELL BIOLOGY 9 The Rockefeller University Press 9

Quantitative analysis of exocytosis and endocytosis in the hydroosmotic response of toad bladder

“…There may be a change in the depth of the cells (measured from luminal to contraluminal plasma membrane). This is consistent with the appearance of the mucosal cells with ADH observed in the scanning electron microscope (Davis et aI., 1974;Spinelti, Grosso & de Sousa, 1975;Mills & Malick, 1978). However, this change in depth For each hem• the actual luminal plasma membrane length (the contour of the membrane including microvilli) of at least 8 consecutive granular cells was measured with a cartographer's wheel, The distance from tight junction to tight junction was measured with a cartographer's wheel by following the cell surface but excluding the microvilli and other irregularities.…”

“…In cells with massive secretory activity, such as mast cells, plasma membrane folds have been correlated with extensive secretion (Burwen & Sat• 1977b). In toad bladder, changes in surface topology at 30 rain ADH exposure would be expected and such changes are seen in scanning electron micrographs (Davis et al, 1974;Spinelli et al, 1975;Mills & Malick, 1978). Table 4, which presents ratios of the dimensions of experimental and control hem• demonstrates that our prediction is borne out.…”

The Surface of the Conjunctiva in Domestic Ruminants

“…Others differ entiate between microvilli and microplicae or ridges [Wong and Martin, 1977;Mills and Malick, 1978;Hodgkins et al, 1978: Pfister andRenner, 1978;Malczak, 1980]. In the conjunctival epithelium of domestic ruminants we were able to clearly find two types of cyto plasmic projections.…”

Localization of ionic pathways in the teleost opercular membrane by extracellular recording with a vibrating probe

“…Rosen, Oliver & Steinmetz, 1974;Mills & Malick, 1978;Vofite & Meier, 1978;Wade, O'Neil, Pryor & Boulpaep, 1979;Marshall & Nishioka, 1980;Stetson, Wade & Giebisch, 1980;Bobrycki, Mills, Macknight & DiBona, 1981;DiBona et al, 1981;Foskett etal., 1981;Husted, Mueller, Kessel & Steinmetz, 1981), histochemical and chemical localization of specific enzymes to specific cell types (e.g. Scott, Sapirstein & Yoder, 1974;Husted et al, 1981;Narbaitz, Kacew & Sitwell, 1981), culture of individual cell types (see Handler, Perkins & Johnson, 1980), and binding of agents to specific cell types (e.g.…”