A supernumerary kidney is defined as a true accessory organ with a collector system, blood circulation and independent encapsulated tissue. In contrast with the horseshoe kidney, this congenital abnormality is extremely rare.1 Kidneydevelopment begins in 2 structures during thefifthweek of gestation: the distal portion of the wolffian duct in which the collector tubules originate, and the renal...

The wound epidermis is a transient secretory epithelium that apposes the mesenchymal blastema of a regenerating urodele limb, and is required for regeneration. Previous studies have shown that the positional identity of the blastema is respecified by retinoic acid (RA; Maden, M. (1982) Nature 295, 672-675), that the blastema contains RA (Scadding, S. R. and Maden, M. (1994) Dev. Biol. 162, 6086...

Inmetazoans, regeneration of lost body parts requiring the formation of a blastema is known as epimorphic regeneration. A blastema is composed primarily of two cell populations: an outer cell layer or ectoderm, derived from the epidermis that covers the wound surface after amputation/fission; and mesenchymal cells that proliferate and accumulate beneath this wound epidermis, eventually differen...

Nine surgically resected Wilms' tumors (WIT) and nude mouse heterotransplants from one WIT were studied by histochemistry and immunohistochemistry. Histochemistry showed acid phosphatase in all cells, while alkaline phosphatase and gamma-glutamyl transpeptidase were present in only some tubules. Using immunohistochemistry, antibodies to the intermediate filaments cytokeratin and vimentin distin...

Explants of 99 adult newt forelimb blastemata (21- to 24-day regenerates) were cultured, with and without implanted dorsal root ganglia, in modified Parker's medium (CMRL-1415) for periods of 72-144 h. Growth and differentiation of the cultured blastemata were compared with ganglionated and non-ganglionated controls fixed at the start of the culture period. The results of these experiments esta...