Skip Navigation

Schematic of events of fertilization of stage 1a and 1b embryos

A. Sperm-oocyte membrane fusion and sperm incorporation 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.

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 et al., 1986. Reproduced with the permission of the publisher, Greenwood Publishing Group.

Keywords: cortical reaction, female pronucleus, fertilization cone, first polar body, interbody, male pronucleus, maturation spindle, second polar body, sperm head, subzonal space, zona pellucida, zonal reaction

Source: The Virtual Human Embryo.