QuestionSBA
QuestionChoice
This answer is incorrect. Cleavage of the embryo at the blastocyst stage (days 4-8) results in monozygotic twins that are monochorionic and diamniotic.
10007452
b
Blastocyst
QuestionChoice
This answer is incorrect. Cleavage of the embryo when the embryonic disc has formed (days 13-15) results in conjoined twins.
10007454
d
Formed embryonic disc
QuestionChoice
This answer is incorrect. Cleavage of the embryo at the implanted blastocyst stage (days 8-13) results in monozygotic twins that are monochorionic and monoamniotic.
10007453
c
Implanted blastocyst
QuestionChoice
This answer is correct. Cleavage of the embryo at the morula stage (day 1-3) results in monozygotic twins that are dichorionic and diamniotic.
10007451
a
Morula
QuestionChoice
This answer is incorrect. Division of the zygote at fertilisation is normal and does not result in twins.
10007455
e
Fertilisation
Concept
Chapter
2693
4598
Twins
Topic
175
Reproductive Physiology
14037
A 24-year-old woman is 21 weeks pregnant with monozygotic twins.

An ultrasound scan reveals that the twins are dichorionic and diamniotic.

At what stage of development did the zygote separate?
a