Explain the events thereafter upto morula stage.

Explanation

Penetration of sperm nucleus induces meiotic division n to form ovum (ootid) and secondary polar body. The fusion of the sperm with ovum, nucleus form zygote, a process called fertilisation, The zygote undergoes cleavage within hours after fertilisation and the young embryo is slowly moving down the fallopian tube towards the uterus. At the end of 4th day the embryo reaches the uterus. It has 8-16 blastomeres and this solid mass of cells is known as morula (little mulberry) as it looks like a mulberry. The morula develops in to blastocyst (64-cells) with a cavity called blastocoel. It undergoes implantation