(i)Secondary oocyte completes meiosis-ll only when a sperm enters its cytoplasm. It forms a larger cell, the ootid and a small cell, the second polar body. (ii)The secondary oocyte is released by the rupture of the Graafian follicle in the process called ovulation.It is moved into the Fallopian tube with the help of fimbriae.It reaches the ampullary isthmic junction of the Fallopian tube, where fertilisation takes place.Cleavage causes formation of 2, 4, 8 and 16 daughter cells called blastomeres. The embryo with 8-16 blastomeres is a solid spherical structure called morula.Cleavage start in the zygote.Morula continues to divide and blastomeres rearrange themselves as it moves further into the uterus.As a result, blastocyst is formed, which contains trophoblast (outer layer) and inner cell mass.The trophoblast attacheds to endometrium (implantation) and blastocyst gets embedded in it.