[Reconstruction of the lumbosacral plexus of an embryo at stage 23 (25mm) and an embryo at stage 16 (7,5mm)].

Two embryos, one at stage 23 and another at stage 16, are reconstructed in view of studying the evolution of the lumbosacral plexus. At stage 16, the sacral plexus begins its development with anastomosis of L5, S1 and S2 roots, while the pelvic member is scarcely sketched. At stage 23, the evolution is complete, the pelvis is entirely constitued and the femoral, sciatic and obturator nerves of adult type. The coccygian plexus is in process of construction.