Skip Navigation
Stage 1 / 1 day Stage 2 / 2-3 days Stage 3-1 / 4 days Stage 3-2 / 4-5 days Stage 4 / 6 days Stage 5a-1 / 7 days Stage 5a-2 / 8 days Stage 5b / 9 days Stage 5c / 12 days Stage 6 / 13-17 days Stage 7 / 16-19 days Stage 8 / 23 days Stage 9 / 25 days Stage 10 / 28 days Stage 11 / 29 days Stage 12 / 30 days Stage 13 / 32 days Stage 14 / 33 days Stage 15 / 36 days Stage 16 / 39 days Stage 17 / 41 days Stage 18 / 44 days Stage 19 / 45-47 days Stage 20 / 49 days Stage 21 / 49-52 days Stage 22 / 52-55 days Stage 23 / 56 days
Carnegie Stage   Figure

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

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.