Embryology Practice Questions With Answers Study Guide Questions And Correct Answers

109. The optic nerve is derived from what embryonic tissue? A. neural crest B. head mesenchyme C. endoderm D. mesoderm E. ectoderm {Ans: E. is correct. The optic nerve is derived from nervous tissue, therefore ectoderm, but not neural crest. Optic sulci of the neural folds forming the forebrain send out the optic vesicles, which then develop into the optic cups connected to forebrain by the optic stalk. The optic stalk becomes the optic nerve.}31. The most important region of the decidua for the nourishment of the conceptus is the decidua ___________. A. frondosum B. capsularis C. parietalis D. basalis E. laeve {Ans: D. is correct. The placenta is made of maternal tissue, the decidua basalis, and fetal tissue, the chorion frondosum or bushy/villous chorion. The smooth chorion or chorion laeve is covered by decidua capsularis, which disappears as the fetus grows and smooth chorion pushes up against he decidua parietalis.}85. In the development of the midgut: A. the superior mesenteric artery is the axis for clockwise rotation of the midgut loop B. the persistence of part of the vitelline duct leads to urachal fistala C. a vitelline cyst may result from abnormal remodeling of the vitelline veins