Activation and the Correlation between Male and Female Elements in Fertilization

Abstract

IN the course of investigations on the process of fertilization, immature rats, which had been allowed to mate, were killed shortly after induced ovulation. Thirty-six animals yielded 477 eggs in the early phase of fertilization. The correlation in the stages shown by the male and female elements in the living eggs was carefully examined with the aid of the phase-contrast microscope. The stages were classified as follows: for the male element, (a) sperm present in the perivitelline space, (b) sperm in the vitellus but with head unchanged, (c) sperm head changing, (d) male pronucleus forming; for the female element, (a) chromosomes in metaphase of second maturation division, (b) in anaphase, (c) in telophase, (d) polar body abstricted, (e) female pronucleus forming. The numbers of eggs showing these stages are recorded in the accompanying table.