Zona Pellucida

The zona pellucida forms to separate the primary oocyte and its enveloping follicular cells. The zona pellucida acts as the extracellular matrix of the egg. When the zona pellucida is penetrated by the sperm, or in some cases disrupted by other means, the egg begins to act upon this fertilization through division. [B]

[9]

Here, the black arrow points to the zona pellucida, which is being penetrated by a hollow needle.

[10]

A close up of an egg similar to that in the above image shows the zona pellucida indicated by the crosshatch.