Zona pellucida as physiological trigger for the induction of acrosome reaction

Abstract

To evaluate the kinetics of acrosome reaction, sperm samples from four fertile donors were prepared by swim-up and incubated with solutions of human zonae containing 0.1, 0.15, 0.3, 0.5 and 1.0 zonae pl-'. After 20, 40 and 60 min of incubation at 37 OC, aliquots were taken for evaluation of the acrosomal status. The results showed a distinct time-and dose dependence of the acrosome reaction induced by solubilized zona proteins. After 60 min of incubation in 1.0 zonae pl-', about 80% of the spermatozoa showed signs of acrosomal loss; about 40% were completely acrosome-reacted. In addition, zona-bound sperm showed the same ratios of acrosome-reacted spermatozoa in control experiments. The velocity of acrosome reaction was calculated by means of a double-reciprocal plot being 2.0-2.5% min-for completely reacted spermatozoa and those showing signs of acrosome reaction. However, both subgroups differed considerably in their constants of equilibrium (K=2.0 ZP pl-' and K=0.2 ZP pl-', respectively). In nonreacted and partly reacted spermatozoa results might indicate a disturbed course of acrosome reaction or possibly the existence of different subpopulations in respect of sperm competition.

Induced cumulus expansion of poor quality buffalo cumulus oocyte complexes by Interleukin‐1beta improves their developmental ability

“…Extent of cumulus expansion is also related to the ability of spermatozoa to penetrate cumulus and reach up to ZP . In this context, number of sperms bound to ZP is an indicator of fertilization potential and subsequent development competence of fertilized oocytes .…”

“…43 Extent of cumulus expansion is also related to the ability of spermatozoa to penetrate cumulus and reach up to ZP. 44 In this context, number of sperms bound to ZP is an indicator of fertilization potential and subsequent development competence of fertilized oocytes. 45 Higher numbers of spermatozoa bound to ZP as observed by JC-1 dye assay in case of BCB+ COCs were reflective of their optimal cumulus expansion features which allowed higher number of spermatozoa to pass through.…”

Zona Pellucida and Progesterone‐Induced Ca2+ Signaling and Acrosome Reaction in Human Spermatozoa

“…Our understanding of ZP-induced [Ca 2ϩ ] i signaling is primarily derived from studies on the mouse. It has been known for some time that solubilized zona induces AR in the human (eg, Cross et al, 1988;De Jonge, 1996;Liu and Baker, 1996;Henkel et al, 1998;Sabeur et al, 1998), and it is clear that, as in the mouse system, this is associated with a rise in [Ca 2ϩ ] i (Patrat et al, 2000b). Studies using recombinant human ZP3 have also detected an elevation of [Ca 2ϩ ] i and induction of AR in human spermatozoa (Brewis et al, 1996).…”

Pregnancy and live birth following the transfer of vitrified–warmed blastocysts derived from zona- and corona-cell-free oocytes

“…The zona pellucida is a glycoproteinaceous surrounding the mammalian oocyte and early embryo. In vivo, zona pellucida has been shown to play a critical role in species-specific spermatozoa-egg interaction, induction of acromosome reaction and avoidance of polyspermy, maintenance of the integrity of a pre-compacted embryo and protection of the early embryo against the maternal immune system (Barnea, 2004;Henkel et al, 1998). Zona-free oocytes are accidentally encountered in IVF when cumulus-oocyte-complexes are mechanically removed by repeat pipetting at the time of mechanical removal of cumulus.…”