21. The time period between fertilization and implantation approximately A. : 1380677.
21. The time period between fertilization and implantation is approximately
A. 5 days.
B. 7 days.
C. 10 days.
D. 14 days.
E. 21 days.
22. Which of the following statements about the syncytiotrophoblast is false?
A. It forms the developing embryo.
B. It is composed of a non-dividing, multinucleated cell.
C. It is nonantigenic, so that it triggers no immune response.
D. It invades the maternal tissues that compose the endometrium of the uterus.
E. It forms lacunae.
23. The cytotrophoblast
A. forms the chorionic villi.
B. replaces the syncytiotrophoblast.
C. remains throughout development.
D. forms branches that protrude into the amniotic cavity.
E. is not an embryonic part of the placenta.
24. The chorionic villi
A. form from branches of the syncytiotrophoblast cords.
B. increase surface area of the amniotic cavity.
C. contribute to the formation of the placenta.
D. are necessary for implantation to occur.
E. are not part of the placental formation.
25. Placenta previa occurs when
A. a normally placed placenta tears away from the uterine wall.
B. the placenta is formed too early.
C. implantation occurs close to the cervix.
D. implantation occurs in the fundus of the uterus.
26. Where does implantation normally occur?
A. in the fundus area of the uterus
B. in the isthmus area of the uterine tube
C. in the cervix area of the uterus
D. in the infundibulum area of the uterine tube
27. The embryonic disk is initially composed of
A. ectoderm and hypoblast.
B. epiblast and mesoderm.
C. epiblast and hypoblast.
D. hypoblast and yolk sac.
E. epiblast and yolk sac.
28. The embryonic membrane that completely encloses the embryo in a watery sac is the
A. yolk sac.
E. ectodermal sac.
29. Gastrulation is the process of development that produces the
B. embryonic disk.
C. germ layers.
D. rudimentary organs.
30. Some epiblast cells migrate and emerge between the epiblast and endoderm as a new germ layer called the
A. yolk sac.
E. primitive streak.