The zona pellucida (ZP) is the outermost layer of egg cells. In other words, it is the first membrane sperm have to cross in order to join the egg cell and fertilize it.
Read the full article on: What Are the Steps of Fertilization in Humans? ( 84).
By Laura de la Fuente Bitane M.D. (gynecologist), Marta Barranquero Gómez B.Sc., M.Sc. (embryologist), Zaira Salvador B.Sc., M.Sc. (embryologist) and Romina Packan (invitra staff).
Last Update: 11/29/2018
