The ability of male pronucleous formation of hamster follicular oocytes matured in vitro was examined by using in vitro fertilization technique of zona-free oocytes.
When hamster oocytes, matured in vitro in a modified Tyrode's solution (mTALP) without amino acids and hormones, were fertilized in vitro, any oocytes could not get the ability to support the development of male pronucleus.
By incorporating 12 amino acids (alanine, arginine, cystidine, glutamine, histidine, isoleucine, leucine, methionine, phenylalanine, proline and valine) and hormones (LH, FSH, PRL and estradiol-17β) in the maturation medium, higher percent (65%) of 75 oocytes gained the ability to support the development of male pronucleus.