Short notes on the process of fertilization in man
In human beings the egg or the ovum should be fertilised as it is moving along the fallopian tube. During copulation about 100 – 200 million sperms are introduced into the vagina of the human female along with the discharge of the semen from the glans penis. This process is called insemination.
The sperms become active and move in all directions but most of them move up, reach the cervix and then move into the uterus. The contraction of the muscles during intercourse helps in sucking the sperms into the uterine opening. From the uterus the sperms find their way into the fallopian tubes where they meet the ovum. The meeting place between the egg and the sperms is usually the upper part of the fallopian tube. Many sperms reach the ovum but only one ultimately gains entry into the egg fuses with it and forms the zygote.
The process of penetration of the sperm into the egg membrane is helped by the secretion of membrane lytic enzymes by the acrosome of the sperm. After the dissolution of the membranes the male pronucleus enters the egg and reaches the female pronucleus. When the two nuclei come into close contact, the nuclear membranes of the two pronuclei disappear and the male and female set of chromosomes arrange themselves together preparing for the zygotic division. The fusion of the male and female pronuclei is called amphimixis.
After -its fertilization the zygote moves down reaches the uterus and becomes implanted in the endometrium.