We attempted to refine a model system for the study of renal parenchymal malformations and demonstrate its use with a preliminary study of the induction of congenital renal dysmorphism. A technique is described whereby 3-day chick embryos are explanted from their shells and cultured in vitro in specially constructed polyethylene chambers. At 8 days of development, the time of ureteral induction of the metanephric mesenchyme, 6-diazo-5-oxo-norleucine, an inhibitor of proteoglycan biosynthesis, is administered as a single microinjection into the posterolateral body wall. Histological examination of fixed metanephric tissue revealed a gross deficiency in the number of differentiated tubules in norleucine-treated animals. A morphometric analysis was made of the actual area occupied by differentiated tubules in the norleucine-treated and control kidneys between 10 and 15 days of development. This analysis revealed a total tubule surface area of control kidneys of more than 2 times greater than that of embryos injected with norleucine at ureteral induction.