27-The Renal System_Global Embryonic Kinetics

The development of the renal system is intrinsically linked to its mesodermal origin and unfolds in several key stages. This process begins at the level of the intermediate plate, which is responsible for the formation of excretory and urogenital tissue. The establishment of the kidney results from compression and flexion of the intermediate mesoderm, influenced by the growth of the neural tube and the approximation of the aortas. These sculpting movements generate a dynamic of longitudinal compression and endorotation, essential for the revitalization of embryonic tissue.

The development of the kidney occurs in a cranio-caudal manner, in three distinct phases: the Pronephros, which is temporary and develops at the cervical level; the Mesonephros, which becomes functional and establishes connections with the aorta; and finally the Metanephros, induced by a ureteric bud, which will give rise to the definitive kidney. This developmental process is marked by a sequence of repositioning and differential growth, where the kidneys, initially in a low position, gradually ascend, while the larger adrenal glands follow this evolution. All these transformations highlight the importance of mechanical forces and embryological interactions in the formation of the renal system.