Deleterious actions of gossypol on bovine spermatozoa, oocytes, and embryos.
Gossypol (50 and 100 micrograms/ml) decreased the percentage of sperm that completed the swim-up procedure. This effect was not blocked by glutathione monoethyl ester. Cleavage rates were not different between oocytes inseminated with gossypol-treated spermatozoa (10 or 50 micrograms/ml) and oocytes inseminated with control spermatozoa. Development to the blastocyst stage at Day 7 after insemination was reduced when spermatozoa treated with 50 micrograms/ml gossypol were used for fertilization. Gossypol toxicity was evident in cows fed cottonseed meal because erythrocyte fragility was greater than for control cows. However, there were no differences between cottonseed meal and control groups in number of oocytes collected per cow, cleavage rate after in vitro maturation and fertilization, or the proportion of oocytes or embryos that developed to blastocysts. Similarly, exposure of oocytes to 2.5-10 micrograms/ml gossypol during in vitro maturation did not affect cleavage rates or subsequent development. In contrast, addition of 10 micrograms/ml gossypol to embryos reduced cleavage rate. Moreover, development of cleaved embryos was reduced by culture with 5 or 10 micrograms/ml gossypol and tended to be reduced by 2.5 micrograms/ml gossypol. In conclusion, bovine gametes are resistant to gossypol at concentrations similar to those in blood of cows fed cottonseed meal. In contrast, the developing embryo is sensitive to gossypol.