Reassembled spherules, obtained from cell suspension of scrambled metanephric kidney from a 11 day old chicken embryos, after mild centrifugation and subdivision of the sediment, where a part is cultured in vitro, reared into Erlenmayer flasks for 10 days in gyratory shaker, and the other in vivo after transplantation into allantochorion membrane of a host embryo of 8-9 days incubation and allowed to grow for 10 days. Not only in vivo, with a good vascolarization of the implant, but also in vitro, with the absolute absence of any blood vessel - and so completely isolated from any " inductive instruction from outside " - we ascertain not only histological differentiation of kidney cells but also the morphogenesis, according to the typical architectural pattern of nephronic elements of the kidney isosystem composed of convolute tubules and the Malpighian corpuscle. The most striking event is the morphogenesis of the glomerolus by podocitic immigration into the Bowman capsule without any capillary partecipation. But the grafts cultured in vivo show the need for the vascularization to complete the functional structure of the glomerolus: the kidney cells compel the capillaries of the host membrane to invade the glomerolus and thus perform the entangled union (now well known by electron microscopy) between podocitic and endenchymal cells. Only at this stage is it possible to discuss on functional activity, or better "prospectic" functional activity, of the reconstitute organ.