Question

explain how sperm each the ova, why they aren't immediately able to fertilize it, and why men whose sperm counts are under 20 million/ml semen are considered infertile

Answer 1

During coitus, a male ejaculates sperms into the female’s vagina, but the oocyte is present at appullary region of the fallopian tube.So inorder to fertilize the ova sperm needs to travel to ampullary region of the tube to fertilizeit.The movement of sperms from the cervix to the isthmus of the uterine tube occurs primarily by their own propulsive action, and to some extent it is also assisted by fluid currents created by uterine cilia. It takes about 2–7 hours for the sperms to reach from the cervix to the isthmus of the tube. This is the reason why sperm cannot fertilize the ova immediately.

During coitus, a male ejaculates about 200–300 million sperms into the female’s vagina. This high number is needed because of the high rate of sperm mortality in the female genital tract. Only 200–300 sperms survive (i.e., only hundreds out of millions) to contact the female gamete. If only 200-300 sperms make it to reach the ova out of 100- 200 million it is unlikely that a person with less than 20 million/ml sperm count could fertilize the Ova .Hence this is why men whose sperm counts are under 20 million/ml semen are considered infertile.