Eggs, sperm & embryos
Sperm must cross the zona to fertilise an egg naturally, and the blastocyst must hatch out of it before implanting. ICSI bypasses the zona, and assisted hatching thins or opens it artificially.
Also known as: egg shell, zona
Related Canada guides
Sources
- Canadian Fertility and Andrology Society (CFAS)
Last reviewed: September 9, 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.