Ionophore A23187 induces acrosome reactions in sea urchin and guinea pig spermatozoa

Abstract
Ionophore A23187, in the presence of extraceullular Ca+2, induces a morphologically normal acrosome reaction in sperm of the sea urchin and precocious acrosome reaction and activation of guinea pig sperm. Increased membrane permeability to Ca+2 is responsible for initiating the acrosome reaction in both sea urchin and guinea pig sperm. In sea urchin sperm, the permeability changes is brought about by egg jelly, whereas in the guinea pig sperm it accompanies capacitation.