Prostaglandins (PGs), E-2, F-2 alpha, 6-keto-F-1 alpha and thromboxane B-2 (TXB-2), produced in vitro by the vas deferens of rats at different stages of sexual maturation (10, 35 and 100 days of age), were estimated by radioimmunoassay. Reversed-phase high-performance liquid chromatography was used to evaluate the RIA and to give a more complete profile, after incubation of the vas deferens with [14C]arachidonic acid. The amount of PGE-2 released into the medium after incubation at 37 degrees C for 5 min increased with age, and was the predominant prostanoid in the adult vas deferens. In prepubertal organs, 6-keto-PGF-1 alpha predominated. TXB-2 was always a minor product. The addition of exogenous arachidonic acid (10 micrograms/ml/20 mg tissue), provoked a higher production of the four compounds. PGE-2 and PGF-2 alpha levels were reduced after castration or hypophysectomy and were re-instated after treatment with testosterone propionate. PGE-2 was much more sensitive to hormonal deprivation than PGF-2 alpha. The production of 6-keto-PGF-1 alpha was not significantly affected by the above treatments.