Question

The stage transferred into the uterus after induced fertilisation of ova, in the laboratory is:
A) Zygote
B) Embryo at 4 blastomere stage
C) Embryo at 2 blastomere stage
D) Morula

Answer 1

Hint: Embryos with more than 8 blastomeres (morula) are used for intrauterine transfer (IUT), which involves transferring them into the uterus.

Complete Step by Step Answer:
The name "morula stage" refers to the developmental stage in which the mass of proliferating cells resembles a mulberry and has 20–30 cells.
A zygote is the result of the fusion of an egg cell and a sperm cell, sometimes referred to as a fertilised ovum or fertilised egg. In the days after conception, the zygote quickly divides from a single cell at first. The 46 chromosomes required are all present in the zygote's single cell, which receives 23 from the sperm and 23 from the egg.
The zygote, which comes before the blastocyst, is split into the morula, a solid mass with 16–32 blastomeres. At the 8-cell stage, a process known as compaction starts, in which the spherical, loosely linked blastomeres take on a flattened polarised cell shape.
The second cleavage event, which results in the 4-cell embryo, happens about 40 hours after fertilisation. The cellular units are referred to as blastomeres. Human embryos begin the process of embryonic genome activation at this stage, which lasts until the 8-cell stage.
Hence, option D is the correct answer.

Note: About 30 hours after conception, the first cleavage occurs, producing a 2-cell embryo. The inner cell mass, which develops into the embryo's precursor, and the trophectoderm, which develops into the placenta's precursor, can both develop as a result of the differentiation of the blastomere.