The<unk>  (or<unk>  mesenchyme, or<unk>  mesoderm) is one of the two embryological structures that give rise to the kidney (the other is the ureteric bud.)
The<unk>  mostly develops into nephrons, but can also form parts of the collecting duct system.
Metanephric blastema
Mesonephros
Yolk sac
Amniotic sac
Callus
Chorionic villi
Atrophodermia Vermiculata
Seminiferous tubules