M. Yoshizawa et al., NATIVE ZONA-PELLUCIDA STRUCTURE IS REQUIRED FOR COMPLETION OF SPERM ACROSOME REACTION IN PORCINE FERTILIZATION, Theriogenology, 41(6), 1994, pp. 1307-1313
In fertilization in vitro, the penetration rate of zona-intact porcine
oocytes by cryopreserved epididymal spermatozoa was about 100% while
that of zona-free oocytes was only 30%. Spermatozoa treated with calci
um ionophore A23187 penetrated both and zona-free oocytes at the rate
of more than 90%. of spermatozoa with solubilized porcine zonae pelluc
idae hardly induced acrosome reaction and did not increase the penetra
tion rate. These results suggest that the structure of the zona is nec
essary for completion of acrosome reaction.