SEM of the proximal tubule of the adult rabbit kidney

Abstract

The present study utilizes the scanning electron microscope (SEMI to reveal the surface morphology of proximal tubular cells and the parietal cells of Bowman's capsule of the adult rabbit nephron. To facilitate the examination of the basal surface of these cells, proximal tubules were dissected free and treated with collagenase t o remove the basememt membrane. Other blocks of tissue were cryofractured to expose the lateral cell surfaces of the proximal tubules. Our investigation has shown that the lateral and basal surfaces of both the convoluted and straight segments of the proximal tubule have numerous processes. However, the arrangement and degree of branching is distinctly different in the two segments. The convoluted segment has large lateral ridges which form a t the base of the microvilli and fan out to divide into lateral-basal processes. Many of the lateral-basal processes reach the basement membrane intact, interdigitating with complementary processes from adjacent cells. However, some of the lateral-basal processes branch into short, knobby projections (basal villi) which may also reach the basement membrane. Patches of basal villi are interspersed between broad regions of interdigitating lateralbasal processes. Therefore, in the convoluted segment, the lateral-basal processes form the major part of the basal cell surface. In tubular cells of the pars recta, unlike convoluted tubular cells, the majority of the ridges remain unbranched and pass directly to the basal surface where they divide into elaborate basal villi. Thus the basal surface of the pars recta cells is highly complex, appearing leaf-like, being a composite of numerous basal villi with a few lateral ridges.The basal surface of some parietal cells of Bowman's capsule have parallel ridges, which results in patches of striations.The complex morphology of cells of the proximal tubule (PT) of the kidney has interested investigators for many years (Wedl, 1850; Heidenhain, 1874; Schachawa, 1876; Landauer, 1895; Zimmermann, 1898; Zimmermann, '11). Heidenhain (1874) was one of the early light microscopists who noted extensive lateral projections on the proximal tubule cells. Subsequent workers have studied kidneys from a variety of animals and corroborated the data of the earlier studies (von Mollendorff, '30; Grafflin and Foote, '39). A renewed interest in the shape of the PT cells has developed with the advent of the scanning and transmission electron microscopes and functional data that suggests a direct relationship of cell shape to function (Rhodin, '58; Bulger, '65; Waugh et al., '67; Andrews and Porter, '74; Bulger et al., '74; Curran and MacIntosh, '62; Diamond and Bossert, '67). Several models of proximal tubule cell shape have appeared in the literature. Welling and Welling ('76) have recently published an elegant quantitative three-dimensional model of the shape of the epithelial cells and intercellular channels in the rabbit proximal tubule. However, the lack of data on the precise ultrastructure of the basal surface has limit...

Renal Functional Effects of Multiple-Tract Percutaneous Access

“…19 The PCNL-treated kidneys were then prepared for wholekidney serial sectioning for morphological analysis. 20 All images from a single serial-sectioned kidney were digitized and assembled into a Quicktime movie to view the PCNL access track=injury complex.…”

Ultrastructural Features of the Rabbit Proximal Tubules.

“…1) (KAISSLING and KRIz, 1979) and by scanning electron microscopy (SEM) for cell surface features (Figs. 2-5) (EVAN et al, 1978(EVAN et al, , 1983. The cells of P, are the tallest (13 jcm including apical microvilli) and most elaborate of all three segments.…”

Three-dimensional Visualization of Renal Cells by NaOH Maceration.

“…In the kidney, Evan and his group exposed the proximal tubule (EVAN et al, 1978) and the collecting duct (WELLING et al, 1981), removing basement membranes and collagen fibers by combined treatments with HCl and collagenase. JoNEs (1985a) observed the basal surfaces of different segments of the urinary tubule by sequential treatment with three kinds of proteases, demonstrating various types of epithelial interdigitation.…”