Mechanisms of Ca2+ liberation at fertilization

The mechanisms underlying the Ca²⁺ release at fertilization of several animal organisms are reported. Four main classical theories are described, i.e., that of Ca²⁺ release following simple sperm contact and a G protein stimulation; that of simple sperm contact followed by a tyrosine kinase receptor activation; that of the necessity of introduction by sperm into the egg of molecules for Ca²⁺ release; and that the molecule introduced into the marine eggs for Ca²⁺ release is the same Ca²⁺. Two other mechanisms for Ca²⁺ release are also illustrated: that of ryanodine receptor stimulation and that of NAADP formation.