CHRONOLOGY OF EVENTS IN THE FIRST CELL-CYCLE OF THE POLYSPERMIC EGG OF THE DOMESTIC-FOWL (GALLUS-DOMESTICUS)

The nuclear population in the polyspermic egg of the domestic hen was examined in whole-mount preparations of the germinal disc. The numbers of nuclei varied in groups of hens from averages of 5.9 to 26, depend ing on days from insemination. Changes in development from initial for mation of pronuclei to the early mitoses of the zygote nucleus were st aged according to the position of the egg in the oviduct. The findings substantiated earlier accounts on the timing of the apposition of the parental pronuclei towards the end of the first cell cycle. Additiona lly, analysis of the spatial distribution of accessory spermatozoal nu clei showed a slight, but significant, dispersal from a clustered arra ngement at this time.