AP BIOLOGY

Detailed explanation-1: -Monozygotic twins happen when a single fertilized egg divides into two. From there, two embryos grow into two babies. Monozygotic ("mono” means one and “zygote” means fertilized egg) is the term used to describe this process. This type of twin formation begins when one sperm fertilizes one egg (oocyte).

Detailed explanation-2: -Embryo splitting or embryo twinning refers to the formation of twins or multiple embryos in vitro to split an embryo in 2-, 4-, or 8-cell stages. The blastomeres can be still totipotent at the initial stage of embryogenesis.

Detailed explanation-3: -Monozygotic twinning (MZT) occurs when an embryo splits after fertilization, resulting in identical twins. The incidence of MZT is 0.42% naturally (in normal pregnancies).

Detailed explanation-4: -Zygotic splitting occurs between days two and six when the zygote divides, usually into two, and each zygote then goes on to develop into an embryo, leading to identical twins (or triplets if it divides into three). These are known as “monozygotic” twins (or triplets).

Detailed explanation-5: -Natural twinning occurs naturally inside the womb of a mother while artificial twinning takes place in the lab inside the Petri dishes. Artificial twinning mimics the natural process of twinning. The splitting of the embryo is done manually in artificial twinning.