Source of sperm and egg’s zinc sparks identified

As a sperm invades a mouse egg, zinc sparks (yellow) fly from pouches beneath the egg's surface (green), kicking off the switch from egg to embryo.

Northwestern University

By Ashley Yeager

December 15, 2014 at 5:33 pm

When egg meets sperm in mammals, zinc sparks fly. These sparks are created when thousands of zinc atoms shoot from thousands of small pouches nestled just beneath the surface of the egg cell, researchers report December 15 in Nature Chemistry. The team used detailed imaging and mapping techniques to capture the outburst and origin of the sparks. The discovery could help scientists figure out how changes in zinc levels control what’s happening in cells and may have implications for identifying the best eggs for in vitro fertilization.

ZINC SHOOTERS As egg meet sperm, zinc sparks fly. This movie
shows the moment of fertilization, revealing hot spots of fluorescence
at the cell surface. These spots are pouches filled with zinc atoms that
erupt to create zinc sparks dancing about the newly minted embryo.
Credit: Northwestern University