Zona pellucida
From Embryology
(Latin, zona pellucida = transparent zone) A specialized extracellular matrix surrounds the developing ][O#oocyte|oocyte]] (egg, ovum) within the ovary and follwing ovulation. It consists of three types of glycoproteins Z#ZP1 ZP1, Z#ZP2 ZP2 and Z#ZP3 ZP3 which have different roles in fertilization.
Following fertilization, the zona pellucida also surrounds the blastocyst during the first week of development, from which it "hatches". The zona pellucida has a role in fertilization, sperm binding, preventing polyspermy, blastocyst development and preventing premature implantation (ectopic pregnancy).
Links: Carnegie stage 3
UNSW Embryology Links: Week 1 - Fertilization | Week 1 - Oogenesis |
