Schematic presentation of the mice kidney development.
Top, Kidney is formed via reciprocal interactions between the Wolffian duct and the metanephric mesenchyme (MM), two precursor tissues derived from the intermediate mesoderm. MM-derived signals, mainly the glial-derived neurotrphic factor (GDNF), induce the budding of the ureteric bud (UB) from the Wolffian duct, into the MM. MM cells condense around the tips of the branching UB, forming the cap mesenchyme (CM).
Bottom, Sequential nephron development: The CM is a subset of cells that constitutes nephron progenitors. CM-derived cells form most of the nephron body (from glomerulus to distal tubule), while the UB-derived cells form the collecting ducts. The CM cells sequentially form the pretubular aggregate (PA), renal vesicle (RV), C-, and S-shaped bodies (CSB and SSB, respectively), and finally the mature nephron.
Proximal–distal patterning along the length of the nephron is evident as early as at the RV stage, at the gene expression level. At the histological level, this patterning is evident at the SSB stage, and can be divided into distinct proximal, medial, and distal segments. The proximal segment is further organized into two distinct epithelial layers, the parietal (Bowman’s capsule) and visceral (podocyte) layers which, together with the invading endothelial and mesangial cells, form the renal corpuscle.