Zona pellucida

Zona pellucidaNo this is not another picture from deep space of a new moon found around Pluto, it’s a beautiful  scanning electron micrograph of the surface of the Zona pellucida.

The Zona pellucida is the strong membrane that forms around an ovum as it develops in the ovary. The membrane remains in place during the egg’s travel through the fallopian tube. To fertilize the egg, a sperm must penetrate the thinning zona pellucida. If fertilization takes place, the zona pellucida disappears, to permit implantation in the uterus.

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