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5
A
B
C
D
E
F |
Ovary
Fallopian tube
Endometrium
Myometrium
Uterine cavity
Spermatozoon penetrates into the oocyte (conception), day 0
Two-cell stage, day 1
Four-cell stage, day 2
Eight-cell stage, day 3
Morula (16-32 cells), day 4
Free blastocyst (following hatching), day 6 |
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Fig. 18
The embryo goes through its cleavage stages while it is migrating along the fallopian tube. As a blastocyst it reaches the uterine cavity at the end of the 5th day. There, the hatching and the embedding into the endometrium occur on the 6th day.
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