Chapter 6

Question 1

During the later stages of pregnancy, maternal
blood is separated from fetal blood by
(A) syncytiotrophoblast only
(B) cytotrophoblast only
(C) syncytiotrophoblast and cytotrophoblast
(D) syncytiotrophoblast and fetal endothelium
(E) cytotrophoblast and fetal endothelium

Answer 1

D. During the later stages of pregnancy, the placental membrane becomes very thin and consists
of two layers, the syncytiotrophoblast and fetal endothelium.

Question 2

Which of the following does not pass
through the primitive umbilical ring?
(A) Allantois
(B) Amnion
(C) Yolk sac
(D) Connecting stalk
(E) Space connecting the intraembryonic and
extraembryonic coeloms

Answer 2

B. The amnion does not pass through the primitive umbilical ring. As craniocaudal folding
occurs, the amnion becomes the outer covering of the umbilical cord.