Question

In vitro fertilization is a technique that involves transfer of which one of the following into the Fallopian tube?
A) Zygote only
B) Embryo only, upto eight cell stage
C) Either zygote or early embryo upto eight cell stage
D) Embryo of thirty two cell stage

Answer 1

Hint: In vitro fertilization or test tube baby technique is a type of assisted reproductive technology (ART) that involves retrieving the eggs from a woman’s ovaries and then fertilizing them with the sperm outside the body. This fertilized egg is known as an embryo which can then be frozen for storage or transferred to a woman’s uterus.

Complete answer:
The process involves monitoring and also stimulating a person's ovulatory process, removing an ovum or from their ovaries and letting sperm fertilize them in a culture medium inside a laboratory. The zygote or the fertilized egg undergoes embryo culture for two to six days, which is then implanted in the same or another person's uterus, for a successful pregnancy. So, it is not necessary that only a zygote can be transferred to the fallopian tube.

Embryo only, up to eight cell stages cannot be transferred to the fallopian tube because in most cases IVF is done to overcome female infertility which is why this procedure takes place inside a laboratory. So, option B is incorrect.

ZIFT which is Zygote Intra - fallopian transfer is an example of IVF. It is a technique in which oocytes and sperms are taken and fertilization takes place outside the female's body which means in vitro. Early embryo with up to eight blastomeres or zygotes is then transferred to the fallopian tube.

When the embryo has reached the blastocyst stage which is on day five, it is more fully developed with multiple cells. At this point the embryo resembles the stage similar to that of an embryo which would naturally be when it enters a uterus for the process of implantation, which can increase the chances of achieving a successful pregnancy. Hence, the embryo of thirty- two cell stages is not transferred to a fallopian tube.

The diagram below depicts In vitro fertilization.

Therefore the correct answer is option ‘C’.

Note: If the embryo has more than eight blastomeres then it is transferred into the uterus which is called as IUT or Intrauterine transfer. IVF may be used to overcome female infertility due to problems with the fallopian tubes, which makes in vivo fertilization difficult. It can also aid in male infertility, where there is a defect in sperm quality.