>Mouse Kidney Development

The development of the kidneys differs from other mammalian organ development because it proceeds through 3 successive phases (pronephros, mesonephros, and metanephros), each forming a more complex pair of kidneys. These kidneys develop in a cranial to caudal progression from the intermediate mesoderm. Mouse kidney development begins when the nephric duct primordium is formed from the nephrogenic cord at E8.5 (~Day 22 in humans). Rostral nephric duct precursors die by apoptosis, while the caudal cells continue to grow towards the cloaca. As the nephric duct migrates down the trunk, it causes the formation of mesonephric tubules within the adjacent nephrogenic cord. The rostral mesonephric tubules then become joined to the nephric duct. The ureteric bud (UB) is formed from the nephric duct that is near the cloaca at E10.5 (~Week 5 in humans). This ureteric bud then grows into metanephric mesenchyme and reciprocal interactions between the ureteric bud and the metanephric mesenchyme induces repeated branching of the UB and the formation of metanephric nephrons from the metanephric mesenchyme. In humans, all of these branches are formed by weeks 32-36 of gestation.

Figure 1. Mouse Kidney Development