The researchers tried two methods to improve the formation of male pronucleus (MPN) after injecting sperm into pig eggs. They added cysteine to the culture medium or treated the sperm with Triton X-100 before injection. The Triton X-100 treatment led to higher egg activation rates after 6 hours compared to cysteine and control groups. However, there were no significant differences in the number of pronuclei between the groups. By 22 hours, all groups had similar activation rates and pronuclei numbers. Cleavage was only observed in the control and Triton X-100 groups, not in the cysteine group. Overall, neither cysteine nor Triton X-100 treatments improved MPN formation, but Triton X-100 did enhance egg activation shortly after injection.