In vitro fertilization is a technique that involves transfer of which one of the following into the fallopian tube?

Either zygote or early embryo upto 8 celled stage.

The correct answer is Option (2)- Either zygote or early embryo upto 8 celled stage.

A large number of couples all over the world including India are infertile, i.e., they are unable to produce children inspite of unprotected sexual co-habitation. The reasons for this could be many–physical, congenital, diseases, drugs, immunological or even psychological.

In vitro fertilisation (IVF–fertilisation outside the body in almost similar conditions as that in the body) followed by embryo transfer (ET) is one of such methods. In this method, popularly known as test tube baby programme, ova from the wife/donor (female) and sperms from the husband/donor (male) are collected and are induced to form zygote under simulated conditions in the laboratory.The technique involves the transfer of either a zygote or an early embryo up to the 8-celled stage into the fallopian tube (ZIFT–zygote intra fallopian transfer) and embryos with more than 8 blastomeres, into the uterus (IUT – intra uterine transfer), to complete its further development.This procedure is part of assisted reproductive technology (ART) and is used to facilitate pregnancy in cases where natural conception is challenging. The zygote or early-stage embryo is typically created outside the body in a laboratory setting through the fertilization of an egg by sperm. After this initial stage, the developing embryo is transferred into the woman's fallopian tube or uterus to establish a pregnancy.