What are twins ? Explain the two types of twins.

Explanation

i. When two embryo develop sumultaneously in the same uterus and two offsprings are delivered from the same pregnancy, they are called as twins.
ii. The two types of twins are `:`
a. Monozygotic twins.
b. Dizygotic twins.
iii. Mmonozygotic twins `:`
During early periodof embroyonic development ( within 8 days of zygote formation ) , cellsof the single embryo divide into two groups and develop as two separate embryos.
Such twins are genetically exactly similar to each other, hence their appearance as well as the gender is same.
In caseof monozygotic twins, if embryonic cells are divided into two groups,8 day after zygote formation they might form conjuoined twins ( Siamese twins ).
iv. Dizygotic twins `:`
Sometimes, two oocytes are released from the ovary of a woman and both are fertilized by two separate sperms. As a result, two separate zygotes are formed. Embryos formed from these zygotesare separately implanted in the uterus and thus, dizygotic twins are formed. Dizygotic twins are genetically different and may be of same of different gender.