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

An embryo in the partial phase of hatching

An embryo in the partial phase of hatching

SEM of a stage 3 embryo in vitro in the partial phase of hatching. Measuring bar = 10µm. Trophoblast cells (T) have ruptured through the zona pellucida (ZP) at the embryonic pole which is unusual. The trophoblast cells are probably zona breaker cells. Reproduced with permission from Y. Nikas whose website is

From: Sathananthan et al., 2003. Printed from Reproductive Biomedicine Online.


Keywords: embryonic pole, partial phase of hatching, trophoblast cells, zona breaker cells, zona pellucida


Source: The Virtual Human Embryo.