Research Progress on the Microregulatory Mechanisms of Fertilization: A Review

The process of fertilization includes sperm capacitation, hyperactivation, an acrosome reaction and the release of acrosome enzymes, membrane fusion and channel formation, the release of the sperm nucleus, and gamete fusion. This process is closely related to the shape and vitality of the sperm, acrosome enzyme release, and the zona pellucida structure of the egg, as well as the opening and closing of various ion (e.g., calcium) channels, the regulation of signaling pathways such as cyclic adenosine monophosphate-protein kinase A, the release of progesterone, and the coupling of G-proteins. The interaction among multiple factors and their precise regulation give rise to multiple cascading regulatory processes. Problems with any factor will affect the success rate of fertilization. Recent studies have shown that with rapid societal development, the incidence of male infertility is increasing and occurs at younger ages. According to World Health Organization statistics, 15% of couples of childbearing ages have infertility problems, of which 50% are caused by male factors. Additionally, the cause of infertility cannot be identified in as many as 60% to 75% of male infertility patients. In this article, we review the research progress on the microregulation of fertilization and mechanisms underlying this process to identify causes and develop novel prevention and treatment strategies for male infertility.