Fig. 5

Graphical sketches show us the changing structural relations between the developing nephron and the perforating radiate artery in the fetal human kidney during late gestation. In the district of progenitor cell recruitment, the space between a perforating radiate artery (PRA, short black arrow) and the lateral aspects of a the pretubular aggregate (PTA), b the mesenchymal to epithelial transition, and c the primitive renal vesicle (RV) is filled with loose mesenchyme. However, in the underlying area of nephron shaping, this distance becomes smaller during development of the d mature, e extending, and f extended renal vesicle. When the g early and h mid-late comma-shaped body (CSB) are forming, an approximation of their lateral aspects with the perforating radiate artery is registered. Furthermore, a transverse interstitial cleft (black/white arrows) is opening at the deep lateral aspect of the i late comma-shaped body. In the j early, k mid, and l late S-shaped body (SSB), this cleft serves the invasion of an afferent arteriole via a short way towards the forming glomerular tuft. Renal capsule (C), collecting duct (CD) tubule, CD ampulla (A), and lumen of the arising nephron +