Effect of styrene maleic anhydride (SMA) on viability and integrity of isolated rat oocytes in vitro.

In vitro spermicidal property of the polymer, styrene maleic anhydride (SMA), a compound under clinical trial as an intravasal male contraceptive, is already established. The present study was designed to evaluate the effect of the polymer (SMA) on the viability and integrity of rat oocytes in vitro. The pH-lowering effect of this polymer was evident following precipitation in Medium 199. Oocytes became nonviable with clearly resolved granulated cytoplasm following incubation with undiluted polymeric first wash medium. Dilution of polymeric wash medium prolonged the integrity and viability of oocytes under incubation. The potency of the first wash medium in terms of affecting the viability of oocytes was highest among different washes and dilutions. Bulging of cytoplasm and an enlarged zona pellucida envelope were observed in a few oocytes treated with the first wash. These findings have shown that, like sperm, oocytes also lose their integrity and viability when coincubated with the polymer or medium containing the polymer. However, developing an appropriate technology for delivery is crucial to exploit this potency of the polymer for development of a female contraceptive. Copyright 2002 Elsevier Science Inc.