1.
The absence of a ventral double-fold of coelomic membrane connecting the heart to the ventral body wall (a ventral mesocardium) is a result of
Correct Answer
E. A bilateral connection of the early intraembryonic coelom rostral to the developing heart
Explanation
The absence of a ventral double-fold of coelomic membrane connecting the heart to the ventral body wall (a ventral mesocardium) is a result of a bilateral connection of the early intraembryonic coelom rostral to the developing heart.
2.
After the twentieth week of gestation, a thinned vasculosyncytial placental membrane is formed consisting of the following three layers:
Correct Answer
C. SyncytiotropHoblast – connective tissue of the villus – fetal capillary endothelium
Explanation
After the twentieth week of gestation, the placental membrane becomes thinned and consists of three layers. The correct answer states that the layers are syncytiotrophoblast, connective tissue of the villus, and fetal capillary endothelium. This arrangement is accurate because the syncytiotrophoblast is the outermost layer of the placental membrane, followed by the connective tissue of the villus, which provides support and structure. Finally, the fetal capillary endothelium is the innermost layer, responsible for the exchange of nutrients and waste products between the maternal and fetal blood.
3.
A 37-year-old women in the fourth month of pregnancy is diagnosed with aggressive ovarian cancer. Her physician advises immediate surgery to remove her ovaries. The woman wants to deliver her baby and has read on the internet that she will have an abortion if her ovaries are removed. She comes to your office for a second opinion. You recommend that
Correct Answer
E. She immediately have the surgery with no hormonal steroid supplements
Explanation
The correct answer is that the woman should immediately have the surgery with no hormonal steroid supplements. This is because ovarian cancer is an aggressive form of cancer that requires prompt treatment. Delaying the surgery until after the birth of the child or until the third trimester of pregnancy could significantly increase the risk to both the mother and the baby. Additionally, hormonal steroid supplements are not necessary for the surgery and may not be safe for the woman or the developing fetus.
4.
Ectopia cordis or Pentalogy of Cantrell is a congenital malformation of the anterior body wall that includes a defect of the lower sternum, a deficient anterior diaphragm, and a heart that lies outside the chest. This condition is primarily a defect in what embryological process?
Correct Answer
B. Lateral folding
Explanation
Lateral folding is the correct answer because ectopia cordis or Pentalogy of Cantrell is a congenital malformation of the anterior body wall that occurs during the process of lateral folding in embryological development. During lateral folding, the embryo's sides fold towards the midline, resulting in the formation of the body wall and the positioning of organs within the body cavity. In the case of ectopia cordis, the failure of proper lateral folding leads to the heart being positioned outside the chest.
5.
Through which blood vessel does the most oxygenated blood flow to supply the fetus?
Correct Answer
C. Aorta
Explanation
The aorta is the largest artery in the body and carries oxygenated blood from the heart to the rest of the body. In the case of a fetus, the aorta is responsible for supplying the most oxygenated blood to the developing baby. This is because the aorta directly connects to the placenta, which is responsible for exchanging oxygen and nutrients between the mother and the fetus. Therefore, the aorta plays a crucial role in ensuring that the fetus receives the necessary oxygen for growth and development.
6.
During Stage 3 of labor, the placenta separates at which layer from the uterus?
Correct Answer
A. Spongy layer of the decidua basalis
Explanation
During Stage 3 of labor, the placenta separates at the spongy layer of the decidua basalis from the uterus. This layer is located between the smooth chorion (chorion leave) and the decidua parietalis. It is at this layer that the placenta detaches from the uterine wall and is expelled from the body.
7.
Which hormone is first produced by the syncytiotrophoblast cells of the early placenta to maintain the viability of the corpus luteum?
Correct Answer
C. Human chorionic gonadotropin
Explanation
Human chorionic gonadotropin (hCG) is the hormone first produced by the syncytiotrophoblast cells of the early placenta to maintain the viability of the corpus luteum. This hormone is crucial in the early stages of pregnancy as it stimulates the production of progesterone by the corpus luteum. Progesterone is essential for maintaining the uterine lining and supporting the pregnancy. Therefore, hCG plays a vital role in ensuring the continued production of progesterone, which is necessary for the viability of the developing embryo.
8.
During the final stages of fetal development (5 months to term) the placental barrier is composed of
Correct Answer
A. SyncytiotropHoblast and endothelial of fetal capillaries
Explanation
During the final stages of fetal development, the placental barrier is composed of syncytiotrophoblast and endothelial cells of fetal capillaries. Syncytiotrophoblast is a layer of cells that forms the outermost layer of the placenta and plays a crucial role in nutrient and gas exchange between the mother and the fetus. Endothelial cells of fetal capillaries are responsible for transporting oxygen and nutrients from the mother's blood to the fetus, as well as removing waste products from the fetal circulation. Together, these two components form the barrier that allows for the exchange of substances between the maternal and fetal circulations.
9.
Which one of the following substances crosses the placental barrier?
Correct Answer
D. IgG
Explanation
IgG is the correct answer because it is the only immunoglobulin that can cross the placental barrier. This allows the transfer of maternal antibodies to the fetus, providing passive immunity to the newborn. IgA, hormones from the pituitary gland, maternal cholesterol, and maternal phospholipids do not cross the placental barrier.
10.
Which of the following structures gives rise to the umbilical arteries and vein?
Correct Answer
A. The allantois
Explanation
The allantois gives rise to the umbilical arteries and vein. The allantois is a structure that develops during embryonic development and is responsible for waste disposal and gas exchange. It connects the developing embryo to the placenta and eventually forms the umbilical cord. The umbilical arteries carry deoxygenated blood from the fetus to the placenta, while the umbilical vein carries oxygenated blood from the placenta to the fetus. Therefore, the allantois is the correct answer as it is directly involved in the formation of the umbilical arteries and vein.
11.
Most drugs taken during early pregnancy are transported across the placental barrier primarily by:
Correct Answer
B. Simple diffusion
Explanation
During early pregnancy, the placental barrier is not fully developed, allowing substances to pass through easily. Simple diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. Since drugs are small molecules, they can passively diffuse across the placental barrier without the need for any specific transport mechanism. Therefore, simple diffusion is the primary method by which most drugs are transported across the placenta during early pregnancy.
12.
Which of the following substances DOES NOT cross the placental barrier?
Correct Answer
B. Triglycerides
Explanation
Triglycerides do not cross the placental barrier because they are too large and cannot pass through the small pores of the placenta. The placenta selectively allows certain substances to pass through to the fetus, such as glucose, amino acids, and IgG antibodies, which are important for fetal development and immunity. Cortisol, a steroidal hormone, can also cross the placental barrier as it is necessary for fetal lung development. However, triglycerides, which are large fat molecules, are unable to pass through the placenta and therefore do not cross to the fetus.
13.
Which of the following cell types is involved in the production of placental estrogen?
Correct Answer
E. SyncytiotropHoblast
Explanation
Syncytiotrophoblast is the correct answer because it is a specialized layer of cells that form the outermost layer of the placenta. These cells play a crucial role in the production of placental estrogen, which is important for maintaining pregnancy and supporting fetal development. The syncytiotrophoblast cells have the ability to convert cholesterol into estrogen, and they also produce other hormones necessary for pregnancy.