Movement of spermatozoa (sperm) to ovum in the process of fertilization is peculiar naturally. How does sperm move? How does it locate an ovum? What mechanisms does sperm use to swim and enter into an ovum? These and many more questions baffle many people. However, the bottom line is that sperms move, break the outer covering of the egg and fertilize it, therefore, a mechanism of the process definitely exists.
Spermatozoa develop from male germ cell in a process known as spermatogenesis. Germ cells undergo mitosis and meiosis to form a differentiated and mature sperm and this takes place in seminiferous tubules (Home Semen Analysis, 2008). Each seminiferous tube joins epididymis, which forms sperm storage. Semen is a clear fluid that carries sperms out of the body. Ejaculation involves two stages: movement of sperm from epididymis and the eventual movement into the urethra where semen moves out of the body.
Ovum on the other hand develops in the process of oogenesis in the ovary. Release of ovum occurs through the process of ovulation and it moves from ovary into oviduct where fertilization takes place. Rupture of the follicle membrane of the ovary pushes the ovum into the ovary. After sexual intercourse, sperm crosses the cervical mucus and travels up the uterus into the oviduct where the ovum lies (Freudenrich, 2009). Sperms have tails, which they use to swim in semen during this process. Numerous sperm surround the ovum and each one tries to penetrate it. Interestingly, out of millions of sperms surrounding an ovum, only one manages to enter it. Acrosome is the head of sperm and it contains enzymes that digest the outer covering of ovum and gain entry. After one sperm enters, the ovum depolarizes and through swelling, it pushes away all other sperm that failed to gain entry. It is only the head of sperm that enters the ovum, enzyme actions on the sperm detach the tail from the head.
Both male and female, have internal and external sex organs that facilitate production, storage and movement of sperms and ova. Male internal sex organs include testes, epididymis, vas, prostrate and urethra. External organs are penis and scrotum. Testes contain the seminiferous tubules where production of sperms takes place. Storage and final maturation of sperms take place in epididymis while vas forms the pathway through which sperms travel from the epididymis into the urethra. All these organs lie in the scrotum, which remains suspended outside the body to maintain favorable temperatures for sperm production. Prostrate is a gland that produces seminal fluids forming semen. Semen is important in the movement of sperm out of male’s body and into female’s body. Urethra on the other hand is a hollow tube through which semen passes out of the body (Home Semen Analysis, 2008). Penis is an external organ and essentially, it aids in transfer of sperms from male parent to a female parent in the process of sexual intercourse. It deposits sperm into the vagina.
Internal sex organs in female include ovaries, oviduct, uterus, cervix, vulva and vagina. Ovaries produce ova and they lie at the end of each fallopian tube. After its production, ovum lies in the oviduct where fertilization takes place. Uterus also called womb, offers site for the fertilized egg, that is, zygote to attach and develop. Cervix is the lower portion of uterus that separates it from the vagina. Cervix allows sperms to move from vagina into the uterus. Vagina picks up sperm after ejaculation in the process of copulation. It is a muscular tube stretching from the uterus to the outside of the body. Unfertilized eggs pass through vagina in the process of menstruation. Vulva is the outermost region of female genitals.
During fertilization, sex organs play crucial roles that facilitate successful fertilization. Fertilization begins with the release of enzymes from the acrosome to digest the outer wall of ovum. Bowen (2000) concurs that fertilization relies on female sex organs. After entering the vagina, sperms are not capable of fertilizing an egg. Therefore, they undergo several processes, which prepare them for fertilization. Sperms undergo capitation to remove seminal plasma proteins, rearrange plasma proteins among others (Bowen, 2000). This enables the sperms to become hyperactive in motility. These processes take place in vagina, uterus and fallopian tube. The oviduct provides a good environment for fertilization to take place.
Fundamentally, fertilization takes place in the oviduct. Oviduct holds the egg in place allowing sperm to locate it hence fertilization. After fertilization, the zygote moves into the uterus where it attaches tom the wall of womb for growth and development. The environment prevailing in the oviduct allows destruction of other sperms that did not enter the egg cell. This ensures that no multiple sperms enter the egg because this may be dangerous. All female sex organs support fertilization prior and after the process. Fertilization cannot occur without ovum so ovaries support fertilization in a way. Uterus holds and sustains the fertilized egg hence supporting the post fertilization events.
Reference
Bowen, R. (2000). Fertilization. 2009. Web.
Freudenrich, R. (2009). How Sex Works. Web.
Home Semen Analysis. (2009). Fertilization and Development. Web.