Question 1

________ Lies between the cytotrophoblast and the epiblast&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The amniotic cavity lies between the cytotrophoblast and the epiblast of the embryonic disc.Cells from the epiblast (amnioblasts)soon form a thin roof over this cavity called the amnion.It is continuous with the epiblast of the embryonic disc.

Question 2

________ Usual site of implantation&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The blastocyst usually implants on the superior part of the posterior wall of the uterine cavity.Implantation occurs slightly more often on the posterior than on the anterior wall.

Question 3

________ Site of the decidual reaction&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The connective tissue in the compact layer of the endometrium in the region of the implanting blastocyst is the site of cellular and other changes known as the decidual reaction.The enlarged decidual cells contain large amounts of glycogen and lipids that provide nourishment for the embryo.

Question 4

________ Lacunar network&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

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 trophoblast and pass to the embryo by way of the extraembryonic coelom.

Question 5

________ Epiblast forms its floor&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

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.

Question 6

________ Ovarian pregnancy&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

Ovarian pregnancy is relatively uncommon,with an incidence of approximately 0.5% of all ectopic pregnancies.In an ovarian pregnancy,fertilization of the oocyte probably occurs in the ampulla of the uterine tube with subsequent implantation in the ovary after becoming dislodged from the tube.Because of intra-abdominal hemorrhage and other medical complications,surgical management is necessary.

Question 7

________ Derived from cytotrophoblast&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The syncytiotrophoblast,a multinucleated protoplasmic mass,is derived from the cytotrophoblast.Cells of the cytotrophoblast divide mitotically,and some of these cells move outward,where they fuse with and become part of the increasing mass of syncytiotrophoblast.The syncytiotrophoblast produces human chorionic gonadotropin,which acts like luteinizing hormone in maintaining the corpus luteum.Later,it also produces other hormones.The syncytiotrophoblast is actively involved in implantation.

Question 8

________ Most common site of an ectopic pregnancy&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The most common site of an ectopic pregnancy is the uterine tube,usually in the ampulla or isthmus.The incidence of tubal pregnancy ranges from 1 in 80 to 1 in 250 pregnancies,depending on the geographic location,socioeconomic level,and age of the pregnant woman.Pelvic inflammatory disease is a common cause of tubal ectopic pregnancy.As the embryo increases in size,the uterine tube ruptures,leading to hemorrhage and a serious threat to the mother's life.

Question 9

________ Abdominal pregnancy&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

In an abdominal pregnancy,the conceptus develops on the peritoneal surfaces of the abdominal cavity.Abdominal pregnancies are relatively uncommon (about 0.03% of all ectopic pregnancies),and they are usually associated with intra-abdominal hemorrhage and severe abdominal pain.Rarely,the embryo continues to develop until term and a live fetus may be delivered surgically.In some cases,the abdominal fetus dies and becomes calcified,forming a so-called stone fetus or lithopedion.

Question 10

________ Develops as a localized thickening of hypoblast&#10;A)Corpus luteum&#10;B)Zona pellucida&#10;C)Prechordal plate&#10;D)Ectopic implantation&#10;E)Chorionic sac

Accepted Answer

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.

Question 11

________ Ventral layer of embryonic disc&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The answer of   ________ Ventral layer of embryonic...

Question 12

________ Extraembryonic coelom&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The answer of   ________ Extraembryonic coelom&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E...

Question 13

________ Surrounds embryo,amnion,and umbilical vesicle (yolk sac)&#10;A)Corpus luteum&#10;B)Zona pellucida&#10;C)Prechordal plate&#10;D)Ectopic implantation&#10;E)Chorionic sac

Accepted Answer

The answer of ________ Surrounds embryo,amnion,and umbilical vesicle (yolk sac)&#10;A)Corpus...

Question 14

________ Develops from a ruptured ovarian follicle&#10;A)Corpus luteum&#10;B)Zona pellucida&#10;C)Prechordal plate&#10;D)Ectopic implantation&#10;E)Chorionic sac

Accepted Answer

The answer of ________ Develops from a ruptured ovarian follicle&#10;A)Corpus...

Question 15

________ Cytotrophoblast&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The answer of   ________ Cytotrophoblast&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E...

Question 16

________ Implantation at internal os&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E

Accepted Answer

The answer of   ________ Implantation at internal os&#10;A)A&#10;B)B&#10;C)C&#10;D)D&#10;E)E...

Deck 2: Formation of Bilaminar Embryonic Disc and Chorionic Sac