Question

Chances of successful fertilisation is higher when:

• A. Sperms are deposited in the vagina before 72 hours of ovulation.
• B. Sexual intercourse takes place after 72 hours of ovulation.
• C. Sperms are introduced into the female reproductive tract before 48 hours of ovulation.
• D. Sexual intercourse after 48 hours of ovulation.

Answer 1

The correct option is C Sperms are introduced into the female reproductive tract before 48 hours of ovulation.

If sexual intercourse takes place within a range of two days (48 hours) before ovulation to one day after it, pregnancy is most likely to occur. This is called the fertile period.

This is because of the difference in the duration of viability of the male and female gametes. Viability refers to the ability of the sperms and oocytes to survive successfully to perform their function.

Sperms can remain viable inside the female reproductive tract for as long as 72 hours (3 days) after deposition in the vagina. But, a secondary oocyte can remain viable for only about 24 hours.

So, for successful fertilisation to occur, both the gametes must be viable during the same time. So, fertilisation can occur during the fertile period only.

If sexual intercourse occurs 72 hours prior to ovulation, the sperms won’t remain viable by the time ovulation occurs. Hence, chances of fertilisation is slim.
If sexual intercourse occurs after 24 hours of ovulation, the oocyte won’t be viable by the time sperms are deposited in the vagina. So, no fertilisation can occur in such a case as well.