Abstract
Adult female mice of ICR-JCL strain were superovulated by intraperitoneal injections of PMS and HCG 48 hr apart. They were killed 1617 hr after injection of HCG and their eggs were recovered under warm mineral oil in a plastic petri dish containing 0.4 ml of incubation medium. Sperm suspension was prepared by suspending a dense mass of sperms recovered from cauda epididymis of adult male into 0.4 ml of incubation medium under mineral oil. The incubation medium was a modified Krebs-Ringer Bicarbonate solution containing glucose, sodium pyruvate, bovine albumin and antibiotics. (Table 1)
At the time of insemination, a drop of sperm suspension (ca. 510μl) was added to the medium containing egg clot. Final concentration of sperm was 100500/mm3.
The percentages of penetrated eggs were 0, 22.8, 96.4, 93.9, 90.9 or 92.7%, when examined at 1/2, 1, 2, 3, 4 or 5 hr after insemination, respectively (Table 2). Thus, in this experimental condition, sperm penetration of zona pellucida starts arround 1 hr and completes within 2 hr after insemination. At 2hr after insemination all the fertilized eggs showed enlarged sperm head and anaphase or telophase of second meiosis, while at 5 hr after insemination, most of them were found to have male and female pronuclei. Average number of sperm per penetrated egg was 1.6 (Table 3) and the rate of polyspermy was 4.1%.
