Which of the following is an important function of the zona pellucida?
A - Provide proteins which bind to the extracellular matrix of the uterine wall and allow the blastocyst to attach
B - Protect the blastocyst from proteases that would break the blastocyst apart
C - None of these are functions of the zona pellucida
D - Prevent the blastocyst from attaching to the wall of the fallopian tube
E - Provide proteases which will digest the extracellular matrix of the uterine wall
Answer: D - Prevent the blastocyst from attaching to the wall of the fallopian tube
The ZONA PELLUCIDA is a layer of extracellular matrix surrounding the mature oocyte, fertilized zygote and pre-implantation blastocyst. It surrounds the developing embryo during its journey through the fallopian tubes and prevents it from implanting prematurely to the wall of the fallopian tube.