Normal range and variation of the zona pellucida–induced acrosome reaction in fertile men

Defective protein kinase A and C pathways are common causes of disordered zona pellucida (ZP)–induced acrosome reaction in normozoospermic infertile men with normal sperm-ZP binding

“…Under this experimental condition, sperm from fertile men will have an average 48% ZPIAR (33). Semen analysis was performed after liquefaction within 1 hour of collection of semen according to the World Health Organization manual (35).…”

“…The number of sperm bound to each of the four oocytes was counted using an inverted contrast microscope, and the average number of sperm bound per ZP was used as the endpoint. All the men with DZPIAR had normal sperm-ZP binding (average R50 sperm bound per ZP) under these experimental conditions, according to the definitions used in our previous studies (9,33).…”

“…The enhanced ZP-induced AR R25% was defined as normal because sperm from fertile men had ZP-induced AR ranging from 20% to 95% (with an average of 48%) and those with ZP-induced AR R25% had no significant impact on sperm-ZP penetration (33,34). Our previous studies in 176 men with two different ejaculates showed that the ZP-induced AR results between ejaculates in the same men were very consistent and highly reproducible (10).…”

“…In fertile men, on average 48% of ZP-bound sperm undergoes the AR in vitro (33). In contrast, with DZPIAR very low proportions of sperm undergo ZP-induced AR (mean 6%, range 1%-16%) (11).…”

Comparison of outcomes of conventional intracytoplasmic sperm injection and intracytoplasmic sperm injection using sperm bound to the zona pellucida of immature oocytes

“…In fertile men, the average ejaculate contains 300-400 Â 10 6 sperm, of which approximately 50% have progressive motility; however, only an average of 14% (range 8%-25%) of motile sperm are capable of binding to the ZP (3). Furthermore, an average of 48% of the ZP-bound sperm undergoes the acrosome reaction (induced by the ZP), which is essential for sperm-ZP penetration and spermoolemma fusion (2,4). Therefore, there is a very small proportion (average <7%) of motile sperm in the ejaculate in fertile men that have the capacity to bind to and penetrate the ZP, which are required for natural fertilization.…”