Which among the following could be transferred into the fallopian tub…

The correct answer is Option (3) → Zygote or early embryo up to the 8-blastomere stage

In vitro fertilisation (IVF) means fertilisation outside the body. Where it is placed depends on its stage. A zygote or an early embryo with up to 8 blastomeres (cells) goes into the fallopian tube; this is ZIFT (zygote intra fallopian transfer). An embryo with more than 8 blastomeres goes into the uterus; this is IUT (intra uterine transfer).

Option (1) Only zygote — Incorrect. A zygote can be placed in the fallopian tube, but it is not the only choice. An early embryo up to 8 blastomeres can also be placed there, so “only” makes the option wrong.

Option (2) Embryo up to the 32-blastomere stage — Incorrect. An embryo with 32 blastomeres has more than 8 blastomeres. Such an embryo is transferred into the uterus (IUT), not into the fallopian tube.

Option (3) Zygote or early embryo up to the 8-blastomere stage — Correct. Both the zygote and an early embryo with up to 8 blastomeres go into the fallopian tube by ZIFT.

Option (4) Only embryo — Incorrect. Only older embryos, with more than 8 blastomeres, are kept out of the fallopian tube. The zygote is also transferred into the fallopian tube, so “only embryo” is wrong.

NCERT Extract:
Infertility – “… 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 zygote or early embryos (with upto 8 blastomeres) could then be transferred 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.”