Identical twins result from the:
A) splitting of embryonic tissue from the same zygote early in development.
B) inner cell mass dividing into two masses during the blastocyst stage of development.
C) fertilization of two different ova by two different spermatozoa.
D) Both A and B are correct.

Question

Quizplus · Accepted Answer

Identical twins occur when a single fertilized egg, or zygote, splits into two embryos. The splitting can occur at various stages of development, but if it occurs early enough, each embryo will have its own amniotic sac, placenta, and set of membranes, resulting in monozygotic (identical) twins. So, options A and B are correct. Option C is incorrect because fraternal twins result from the fertilization of two different eggs by two different sperm.

Identical Twins Result from The