Question

(a) Where does fertilization occur in humans? Explain the events that occur during this process.
(b) A couple where both husband and wife are producing functional gametes, but the wife is still unable to conceive, is seeking medical aid. Describe any one method that you can suggest to this couple to become happy parents.

Answer 1

Fertilization occurs in the fallopian tube in humans. The sperms swim and come in contact with the zona pellucida. It releases hormones / secretions which induce changes in the membrane and hydrolyzes the ovum membrane. One sperm enters and blocks the entry of other sperms thereby ensuring only one sperm fertilizes the ovum and prevents polyspermy. Entry of sperm induces completion of second meiotic division forming ovum and second polar body. The haploid nucleus of sperm and that of ovum fuses. Formation of diploid zygote takes place thereby completing the process of fertilization.

The method suggested to the couple who are unable to conceive:

IVF (in vitro fertilization) - In this process ova from the wife and sperm from the husband are collected and induced to form zygote under laboratory conditions. A zygote or early embryo are then transferred to the fallopian tube or into the uterus to complete further development.