Fig. 4From: Concepts for a therapeutic prolongation of nephrogenesis in preterm and low-birth-weight babies must correspond to structural-functional properties in the nephrogenic zoneTransmission electron microscopy of a 1-day-old and glutaraldehyde-fixed rabbit kidney shows cell-to-cell contacts in the renal stem cell niche. A projection (arrow) of a mesenchymal cell (MES) is crossing the interface to establish a contact with epithelial (EPI) cells via tunneling nanotubes (arrow head). The basal lamina of epithelial cells on a CD ampulla is marked by a crossBack to article page