In order to be apt for fertilization epididymal spermatozoids must capacitate. The process of capacitation emerges inside the feminine genital tract. The exact biochemical and physiological mechanisms responsible for spermatozoid’s capacitation aren’t exhaustively understood.
Nowadays, with the aid of in-vitro modern techniques, new clinical studies with the purpose of increasing human fertility are developed.
In the clash between the spermatozoid surfaces and the pellucid zone of the oocyte, an inside the spermatozoid is triggered an acrozomal reaction; during this reaction the acrosome becomes a vesicle, establishing a contact between the membrane plasmatic components and the acrosome and creating a hybrid vesicular membrane. The resulted exocytic process is due to the oocyte exposure to acrosome’s lytic enzymes like: hyaluronidases, lipases, glycoside hydrolases (glycosidases), proteinosis and others.
A very important domain of research is acrozomal reaction regulation, because it has a crucial importance in the study of fertilization and, any dysfunction at this level leads to infertility. The factor which governs this reaction is the ionic regulation; and any unbalances lead to infertility. Positive calcium ion influx triggers the acrozomal reaction and propagates the electric charge through spermatozoid membrane which now is capable to fuse with the egg’s membrane. It has also been scientifically proven that the ions of sodium play an important role in the process of fertilization; in the environment surrounding the spermatozoid must be large quantity of ions of sodium to trigger the acrozomal process of exocytose. After recent scientific studies related to the ionic control of acrozomal reactions the following conclusions have been stated:
1.The activation of a sodium-proton exchange increases the intracellular level of sodium;
2.The sodium intracellular level increase leads to pH elevation;
3.Increased pH leads to calcium channels activation which help extracellular calcium enter spermatozoid cytoplasm;
4.Intracellular elevated calcium level leads to exocytose.
In the complex process of oocyte and spermatozoid coalescing, there are many factors which modulate the acrozomal reaction. Progesterone acts upon the spermatic membrane; it requires internal calcium elevation, which is extremely important in the process of spermatozoid exocytose; it involves a chlorine ions influx which apparently uses a unique steroid receptor.
It is very important to acknowledge that there are many intricate complex events which happen previously to fecundation there are biochemical and functional details that science hasn’t yet been able to fully explain and that would surely make an important difference in the future, in scientists’ attempt to treat and cure male infertility.