Question

The site of fertilization in mammals is
A. Ovary
B. Uterus
C. Vagina
D. Fallopian tube

Answer 1

Hint: Fertilization is the main event in sexual reproduction. It is characterized by the fusion of the male gamete with the female gamete resulting in a zygote formation. The cilia in the oviduct help move the egg towards the uterus. Fertilization occurs in tubular structures also called oviducts.

Complete answer: Fertilization is represented by the fusion of male and female gametes, viz. sperm and egg respectively. The product of fertilization is a zygote that develops to form a new individual. Fertilization occurs mostly inside the female body like in humans. In some cases, it occurs outside the female body like in frogs. The female reproductive system consists of ovaries, oviduct or fallopian tubes, uterus, and vagina. Ovaries function to produce eggs and many female sex hormones that affect the secondary sexual organs. The fallopian tubes or oviducts are tubular structures made of three parts called the infundibulum, ampulla, and Isthmus. The infundibulum is the hand-like structure that receives the egg from the ovary. The ampulla is the site where fertilization of the egg occurs. It is in the ampulla where the egg stays for 24 hours till fertilization. After fertilization, the egg travels towards the uterus through the isthmus that has ciliated cells. If the egg gets fertilized, it completes its remaining stages of cell division and enters the uterus to get attached to the uterine lining. So, the uterus is the structure that holds the fertilized egg through placenta formation. So, we can conclude that the site of fertilization is the fallopian tube or the oviduct.
Hence, option D is the correct answer.

Note: The egg stays in the ampulla of the fallopian tube up to 24 hours, after which it dies and degenerates leading to the menstrual cycle. The fallopian tube is around 10-12 centimetres in length. The cilia in the infundibulum of the fallopian tube help in the movement of the egg toward the uterus even if it is not fertilized.