Question

Name and describe very briefly, the stages in the development of human embryo.

Answer 1

1. After fertilization zygote is formed inside the fallopian tube.
2. The zygote then divides repeatedly to form a spherical mass of cells known as ‘Morula’.
3. The morula then develops into a hollow sphere of cells with a surrounding cellular layer and an inner cell mass projecting from it centrally. This stage is known as the ‘blastocyst’. It implants itself into the uterine wall.
   
4. From the blastocyst arises an embryo which is around 3 weeks old. It is a tiny organism that hardly resembles a human being.
5. By the end of 5 weeks, the embryo is with a develops heart and blood vessels.
6. By the end of 8 weeks, limbs are developed. This stage is known as ‘foetus’.
7. At the end of nearly 40 weeks i.e. the end of the gestation period, the infant is born.