Question

Site of fertilization in a mammal is
A. Ovary
B. Uterus
C. Vagina
D. Fallopian tube

Answer 1

Hint: During copulation (coitus) semen is released by the penis into the vagina of female, called insemination. Sperms move in the liquid medium secreted by the female genital tract a speed of 1.5 - 3.0 mm/minute. Prostaglandins of semen help in the movement of spermatozoa. The process of fusion of a sperm with the ovum is called fertilisation.

Complete answer:
Entry of $\mathop {Ca}\nolimits^{2 + } $ into sperms causing rapid whiplash movements of the tail part. They swim through the vagina, cervix, uterus and finally reach the junction of the isthmus and ampulla called ampullary-isthmic junction of the fallopian tubes. The ovum released by the ovary is also transported to the ampullary Isthmic junction where fertilisation occurs. Ovum is released in the secondary oocyte stage (arrested in metaphase II). Due to ciliary current produced by the fimbriae portion of oviduct, ovum is drawn in through ostium. It reaches ampulla, the site of fertilization, by the ciliary action of ciliated columnar epithelial lining of oviduct.
Now let us match this with given options:-
Ovary :- it produces ova and female sex hormones oestrogen and progesterone and do not play role in fertilisation.
Uterus :- it is a pear shaped structure and is the site of foetal growth during pregnancy and does not play a role in the site of fertilisation.
Vagina :- it is an external copulatory organ. The sperms enter through it but do not play the role of site of fertilisation.
Fallopian tube :- it is also called as oviduct and fertilisation occurs in the ampullary – isthmic junction which is part of the oviduct. Thus this option is correct.

Our required answer is option D that is fallopian tube.

Note: Once the ejaculation occurs in the semen, sperm lives only for 48 to 72 hours outside the body. Sperms move in the liquid medium secreted by the female genital tract at a speed of 1.5 - 3.0 mm/minute.
Prostaglandins of semen help in the movement of spermatozoa. Once the sperms are released
Capacitation of sperm occurs in the female genital system and involves.