Question

Short / Long Answer question Type :
Write short notes on Implantation

Answer 1

After fertilisation, a two cells embryo/zygote is formed. It enters into the cleavage stage. As cleavage proceeds, the ovum has 16 cells, called a morula. Morula consists of an inner and outer cell mass. The outer cell mass give rise to Trophoblast. This morula keeps on dividing and forms blastocyst which have a cavity called blastocoel. By this time the embryo has traveled down the uterine tube and is prevented from sticking to the epithelium by zona pellucid. During this period embryo receives nutrition from the substances stored within the worm. By the time a blastocyst is formed embryo needs additional sources of nutrition. This nutrition is received, when the blastocyst sticks to the uterine endometrium and gets implanted in it.