11) The mesoderm forms (the)

A) muscle.

B) epidermis.

C) neural tissues.

D) mucous epithelium of nasal passageways.

E) pituitary gland and adrenal medullae.

12) The first extraembryonic membrane to appear is the ________.

A) chorion

B) allantois

C) placenta

D) yolk sac

E) amnion

13) The ectoderm forms which of the following?

A) muscle

B) all lymphatic structures

C) the cardiovascular system

D) the thymus, thyroid gland, and pancreas

E) all neural tissues

14) The extraembryonic membrane that contains fluid that surrounds and cushions the developing embryo and fetus is known as the

A) yolk sac.

B) amnion.

C) allantois.

D) chorion.

E) uterus.

15) The extraembryonic membrane that forms the urinary bladder is the

A) placenta.

B) allantois.

C) amnion.

D) chorion.

E) yolk sac.

16) Which of the following is formed when blood vessels form in the chorion, around the periphery of the blastocyst?

A) allantois

B) placenta

C) blastocoele

D) amnion

E) trophoblast

17) The morula stage occurs during which process?

A) embryogenesis

B) placentation

C) gastrulation

D) implantation

E) cleavage

18) The hollow cavity within the blastocyst is the ________.

A) gastrula

B) morula

C) blastocoele

D) yolk sac

E) amnion

19) The yolk stalk and body stalk fuse during week five, forming the ________.

A) amnion

B) allantois

C) chorion

D) umbilical stalk

E) placenta

20) Which extraembryonic membrane is an important site of blood cell production?

A) placenta

B) yolk sac

C) amnion

D) allantois

E) chorion