Microsurgical Injection of Spermatozoa into Hamster Eggs with Subsequent Transformation of Sperm Nuclei into Male Pronuclei

Abstract

Isolated nuclei of hamster spermatozoa develop into male pronuclei when injected into hamster eggs. The nuclei of fresh, frozen-thawed and freeze-dried human spermatozoa are equally capable of developing into male pronuclei when injected into hamster eggs. These results indicate that sperm nuclei are stable organelles and the egg cytoplasmic factors controlling the transformation of sperm nuclei into male pronuclei are not strictly species-specific.