Three-dimensional visualization of renal cells by NaOH maceration.

The three-dimensional fine structure of cells composing the renal tissue was demonstrated by SEM after the removal of extracellular matrices by NaOH maceration. This paper focuses on glomerular mesangial cells, Goormaghtigh's cells (extraglomerular mesangial cells), and epithelial cells in the thin limbs of Henle's loop in the rat, rabbit and dog. Mesangial cells reveal rough surfaces covered with short microvilli. The cells extend long branching processes in close association with the glomerular capillary, suggesting a role for them of regulating the capillary caliber. The mesangial cells interdigitate with each other by their microvilli, forming an intercellular labyrinth. Goormaghtigh's cells at the glomerular hilus are also covered with microvilli, which form narrow labyrinthine spaces between the cells. The labyrinth among the mesangial cells and that among Goormaghtigh's cells connect with each other at the hilus, giving rise to a channel system leading from the periphery of the glomerulus through the hilus to the interstitial space outside the glomerulus. Renal tubule cells display complicated intra- and intercellular interdigitations on the basal aspect. The pattern of epithelial interdigitation is specific to each tubular segment. The descending and ascending thin limbs of the long loops demonstrate a striking contrast to each other. The former is characterized by moderate intercellular interdigitation and by numerous microvilli on the lateral and basal surfaces; the latter is marked by elaborate, pectineal interdigitations, and by smooth basolateral surfaces.