Unfertilized oocyte

Unfertilized oocyte

Scanning electron microscope images of an unfertilized oocyte of Illex coindetii showing (a) the micropyle situated on the animal pole (indicated by an arrow), (b) the shallow oval cavity of the micropyle and (c) the detail of the opened and round micropyle. After 24 hours of in vitro fertilization, (d) the closed micropyle can be recognised on the egg