What is Which of the following is NOT related with fertilization: and explain in detail?
Ans. (d) Zona reaction attracts the spermsRef.: D.C. Dutta 8th ed. / 23, 7th ed/ 21Once an ova is fertilized, zona reaction takes place.* Zona reaction-Once sperm penetrates zonapellucida, the ovum become impermeable to other sperms, this prevent polyspermy. Therefore zona reactions DOESN'T ATTRACTS sperm.* When more than one sperm manages to enter the ovum (dispermy = 2; triploidy = 3), the fetus nearly always aborts* 1st Cell division then occur (20hour)-> give rise to two-cell embryoComplete Steps of Fertilization# Capacitation - A period of conditioning that occurs in the female reproductive tract.# Chemotaxis -sperm are attracted to an egg through the process known as chemotaxis# Binding of progesterone + surface receptor on the sperm- increase in intracellular calcium ion concentration- which increases sperm motility (chemokinesis).* Acrosome reaction (perforations form in the acrosome) occurs in ampulla* Zonapellucida is a glycoprotein layer surrounding the membrane of oocytes (see image).* Once sperm reached ova, there is release of hyluronidase - penetration of corona radiata and cumulus cells by sperm.* Glycoproteins on the outer surface of the sperm then bind with glycoproteins on the zonapellucida of the ovum.* Release ofacrosin occurs ->Acrosin digests the zonapellucida and membrane of the oocyte* After this Sperm enters the cytoplasm ->>intracytoplasmic structures, the coronal granules, arrange themselves in an orderly fashion (around the outermost portion of the cytoplasm just beneath the cytoplasmic membrane). Swelling of sperm head then occurs, giving rise to male pronucleus.* Doing this the egg completes its second meiotic division, casting off the second polar body to a position also beneath the zonapellucida.