Repeated vas occlusion and non-invasive reversal with styrene maleic anhydride for male contraception in langur monkeys

The feasibility of a spacing method for contraception, using Styrene Maleic Anhydride (SMA) as a vas occlusive agent, has been assessed in male langur monkeys. The vas deferens of 6 animals were occluded with 60 mg SMA in 120 mu L DMSO. After 150 days, the occlusion was reversed by a technique which involved palpation, percutaneous electrical stimulation, forced vibratory movement, suprapubic percussion and per-rectal digital massage of the vas s egments. The vas deferens were then re-occluded with SMA and reversed by th e non-invasive method after three consecutive azoospermic samples. The seco nd vas occlusion resulted in uniform azoospermia after the third ejaculatio n and reversal caused the reappearance of spermatozoa in the semen to sever e oligozoospermic levels in the first two ejaculations and rising to normos permia in the subsequent ejaculations. Ultrastructure of the spermatozoa by SEM and TEM and sperm function tests revealed that the spermatozoa had rec overed normal morphology. Vas morphology also regained a normal pseudostrat ified columnar epithelium containing basal and principal cells. The results suggest that the SMA-based spacing technique for male contraception could be extrapolated to the human by use of no-scalpel injection and non-invasiv e reversal.