Induction and inhibition of outgrowth and development of renal collecting duct epithelium.

Renal cortical explants consisting of capsula fibrosa with an adherent thin layer of collecting duct anlagen, S-shaped bodies, and nephrogenic blastema were isolated from newborn New Zealand rabbits and cultured in Dulbecco's Modified Eagle's medium for 24 hours. Within this period of time, the explants formed globular bodies surrounded by an epithelium of differentiated collecting duct cells. The outgrowth of the collecting duct cells and the formation of the epithelium occurred only when serum was added to the cultivation medium. Different types and different concentrations of serum were tested; fetal bovine serum and newborn and adult rabbit sera at concentrations of at least 5% induced the outgrowth and spreading of the cells. The surrounding epithelium did not develop in the absence of serum. The outgrowth of the collecting duct cells in serum-supplemented cultivation media was arrested by inhibitors of protein and glycoprotein synthesis and by cytoskeletonal-blocking agents such as cycloheximide (1 x 10(-6) M), actinomycin C1 (2 micrograms/ml), tunica-mycin (1 microgram/ml), 6-diazo-5-oxo-norleucine (2 x 10(-5) M), vinblastine (5 x 10(-6) M), colchicine (1 x 10(-3) M), and cytochalasin B (2 micrograms/ml). In contrast, inhibitors of DNA synthesis, e.g., cytosine arabinoside (2.5 x 10(-5) M), mitomycin (1 x 10(-6) M), and hydroxyurea (2.5 x 10(-3) M), had no influence on the outgrowth.