Stage 1b - Figure 1

Fig.1. Schematic of Events of Fertilization in Stage 1a and 1b Embryos

CR, cortical reaction, FC, fertilization cone; FPn, female pronucleus; Ib, interbody; MPn, male pronucleus; PB1, first polar body; PB2, second polar body; SS, subzonal space; S, sperm head; Sp, maturation spindle; Z, zonal pellucida; ZR, zonal reaction.

(From: Sathananthan, Trounson, and Wood, 1986. Reproduced with the permission of the publisher, Greenwood Publishing Group.)

A. Sperm-oocyte membrane fusion and sperm incorportation into the oocyte cytoplasm.

B. Cortical and zonal reactions composed of exocytosis of cortical granules and interaction of their contents with the zona pellucida, respectively;.

C. Extrusion of the second polar body, completing second maturation.

D. Early pronuclear formation from the maternal and paternal chromosomes.