Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts
... [Show More] indicated by letters or by a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly and then insert the letter in the space to the right of the appropriate number.
Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading.
1.
Extraembryonic coelom
a. A
b. B
c. C
d. D
e. E
2.
Cytotrophoblast
a. A
b. B
c. C
d. D
e. E
3.
Lacunar network
a. A
b. B
c. C
d. D
e. E
ANS: A
The lacunar networks form by coalescence of lacunae in the syncytiotrophoblast. As the maternal sinusoids are eroded, blood seeps into these networks. Nutrients in the embryotroph
diffuse through the two layers of tropNhoUbRlaSstIaNndGpTaBss.tCo OthMe embryo by way of the extraembryonic coelom.
4.
Epiblast forms its floor
a. A
b. B
c. C
d. D
e. E
ANS: B
The floor of the amniotic cavity is formed by the epiblast. The amnion enclosing the amniotic cavity is attached to the epiblast of the embryonic disc. Initially, some amniotic fluid may be secreted by the amniotic cells, but most of it is derived from the maternal blood.
5. Develops as a localized thickening of hypoblast
a. Corpus luteum
b. Zona pellucida
c. Prechordal plate
d. Ectopic implantation
e. Chorionic sac
ANS: C
The prechordal plate indicates the future cranial end of the embryo and the future site of the mouth. It is a circular area of endoderm that is firmly adherent to the overlying embryonic epiblast. It is an important landmark in the early embryo and serves as an organizer of the cranial region of the embryo.
6. Develops from a ruptured ovarian follicle
a. Corpus luteum
b. Zona pellucida
c. Prechordal plate
d. Ectopic implantation
e. Chorionic sac
ANS: A
The corpus luteum develops from the ovarian follicle after ovulation. Under the influence of luteinizing hormone (LH) produced by the adenohypophysis (anterior lobe of pituitary gland), the ruptured follicle develops into a glandular structure. At ovulation, the walls of the follicle collapse and, with cells of the theca folliculi, form the corpus luteum. The corpus luteum is an important source of progesterone for about 4 months. After this, the placenta is the major producer of this hormone.
7. Surrounds embryo, amnion, and umbilical vesicle (yolk sac)
a. Corpus luteum
b. Zona pellucida
c. Prechordal plate
d. Ectopic implantation
e. Chorionic sac
ANS: E
The chorion forms the chorionic sac from the wall of which the embryo, its amnion and umbilical vesicle are suspended by the connecting stalk. The chorionic sac gives rise to the embryonic part of the placenta.
8.
Derived from cytotrophoblast
a. A
b. B
c. C
d. D
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