The mammalian glomerulotubular junction studied by scanning and transmission electron microscopy

The structure of the junction of glomerulus and tubule was investigated in man and 5 other mammalian species (rat, mouse, ferret, rabbit and pig) by scanning and transmission electron microscopy. The junction between parietal epithelium and proximal tubular epithelium was usually abrupt but varied in position: inside Bowman's capsule, especially in the male mouse; at the anatomical tubular origin, in the rat, ferret and man; and down the tubule, in the rabbit. All animals but especially the pig had cells intermediate in appearance between parietal and tubular cells at the junction. Serial sections of 3 rat junctions studied by transmission electron microscopy showed a variety of appearances of the arrangement of parietal and tubular cells, but the glomerular aspect of the first tubular cell up to its microvillous border was always covered by parietal epithelium, even though this was reduced to a thin sheet in places. This arrangement appeared to be the rule in all species studied.