Fig. 9

View onto the installation of the S-shaped body (SSB) in the fetal human kidney during advanced pregnancy by the optical microscope. Its connecting tubule (CNT) with the related distal pole (DP) is positioned near the proximal end of the regenerating pretubular aggregate (PTA). Depending on the environmental physiological conditions, at this meeting, a further nephron in form of a primitive renal vesicle can principally appear. At the lateral aspect, the elongating distal tubule is exposed to a neighboring perforating radiate artery (PRA). The progenitor cell strand (white arrow heads), which earlier lined to the pretubular aggregate, is yet dissolved by the installation. At the deep lateral aspect, the glomerulus defoliates along a narrow interstitial cleft (white triangles). This is bordered at the top by the expanding proximal tubule. Most decisively, it is invaded by interstitial cells so that as well as the afferent and efferent arterioles as the intra- and extraglomerular mesangium at the arising glomerulus can establish. Within the glomerulus, the visceral layer including the podocytes (P) and the parietal layer representing the Bowman’s capsule (BC) are visible. The later represents the proximal pole (PP), which is mounted next to the connecting tubule of a previously developed nephron. At the medial aspect of the S-shaped body, the vertical interstitial cleft (white circles) lines yet along the differentiating collecting duct (CD) tubule, the neck (N) and the conus (CO) of the CD ampulla (A) towards the center of the S-shaped body. The forming proximal, intermediate, distal, and connecting tubule portions become covered by an own faint peritubular interstitium C renal capsule, black asterisks interface between the nephrogenic mesenchymal and epithelial progenitor cells in the niche, white asterisks adhesion