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Question 1
Correct
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All of the following statements are true about Androgen insensitivity syndrome except:
Your Answer: The chromosomal sex is 46XX
Explanation:Patients suffering from androgen insensitivity syndrome have 46XY chromosomes. Due to insensitivity to androgens, they have female characteristics e.g. scant pubic or body hairs, enlarged mammary glands, and a small penis.
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This question is part of the following fields:
- Embryology
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Question 2
Correct
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In the non-pregnant state which of the following hormones is secreted by the corpus luteum?
Your Answer: Progesterone
Explanation:The Corpus Luteum is a temporary endocrine structure that secretes two steroid hormones: 1. Progesterone (17a Hydroxyprogesterone) and 2. Oestradiol. The corpus luteum also secretes Inhibin A. In the menstrual cycle if fertilisation doesn’t occur the corpus luteum stops secreting progesterone and degenerates into a corpus albicans. If fertilisation occurs hCG signals the corpus to continue progesterone production and it is then termed the corpus luteum graviditatis
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This question is part of the following fields:
- Embryology
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Question 3
Correct
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Which structure is the primary mechanism for shunting blood away from the fetal pulmonary circulation?
Your Answer: Foramen Ovale
Explanation:Oxygenation of fetal blood occurs in the placenta before it returns in the umbilical vein which joins the left branch of the portal vein. It bypasses the capillaries of the liver by going through the ductus venosus, which is obliterated after birth and becomes the ligamentum venosum. The oxygenated blood enters the inferior vena cava and is transported to the right atrium and
then through the patent foramen ovale to the left atrium and on to the left ventricle. From the left ventricle, the blood flows into the aorta and through the fetal vascular network. Blood returning from the head of the foetus passes through the superior vena cava to the right atrium and straight on to the right ventricle and pulmonary artery. However, it does not enter the pulmonary
circulation, being short-circuited by the ductus arteriosus to the aorta. Aortic blood is carried via the umbilical arteries back to the placenta for reoxygenation. At birth, the three short circuits, the ductus venosus, foramen ovale and ductus arteriosus, close. -
This question is part of the following fields:
- Embryology
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Question 4
Incorrect
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How many days after fertilisation does the blastocyst form?
Your Answer: 4 days
Correct Answer: 5 days
Explanation:Shortly after the Morula enters into the uterus, approximately on the 4th day after fertilization a fluid filled cystic cavity appears in the morula and transforms the morula into a blastocyst.
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This question is part of the following fields:
- Embryology
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Question 5
Correct
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The best confirmatory test for Turner's syndrome is done by:
Your Answer: Chromosomal analysis (Karyotyping)
Explanation:Standard karyotyping is the best confirmatory test for the diagnosis of Turner syndrome among patients who have some doubtful clinical presentations. It is done on peripheral blood mononuclear cells.
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This question is part of the following fields:
- Embryology
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Question 6
Correct
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Branches V2 and V3 of the trigeminal nerve develop from which pharyngeal arch?
Your Answer: 1st
Explanation:Trigeminal nerve has three divisions, the first is the ophthalmic division that does not originate from any of the pharyngeal arches, the second and third divisions, namely, the maxillary and the mandibular region develop from the first pharyngeal arch.
Pharyngeal Arches:
1st = Trigeminal V2 & V3 (CN V)
2nd = Facial (CN VII)
3rd = Glossopharyngeal (CN IX)
4th and 6th = Vagus (CN X) -
This question is part of the following fields:
- Embryology
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Question 7
Correct
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Which of the following hormones is secreted by the corpus luteum in a non pregnant state?
Your Answer: Progesterone
Explanation:The corpus luteum is formed from the granulosa cells of the mature follicle. The structure functions as a transient endocrine organ which secretes mainly progesterone with additional secretion of oestradiol and inhibin, which serve to suppress FSH levels. In the event of no pregnancy, the corpus luteum stops producing progesterone and degenerates into the corpus albicans.
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This question is part of the following fields:
- Embryology
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Question 8
Correct
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How many days after fertilisation does the blastocyst hatch from the zone pellucida?
Your Answer: 5-Jul
Explanation:Shortly after the morula enters the uterus, around the 4th day after fertilization, a clear cystic cavity starts forming inside the morula. The fluid passes through the zona pellucida from the uterine cavity and hence forms the blastocyst.
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This question is part of the following fields:
- Embryology
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Question 9
Correct
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When does Oocytogenesis complete?
Your Answer: Birth
Explanation:During the early fetal life, oogonia proliferate by mitosis. They enlarge to form primary oocyte before birth. No primary oocyte is form after birth. The primary oocyte is dormant is the ovarian follicles until puberty. As the follicle matures, the primary oocyte completes its first meiotic division and gives rise to secondary oocyte. During ovulation the secondary oocytes starts the second meiotic division but is only completed if a sperm penetrates it. This 1st and 2nd meiotic division is known as ootidogenesis.
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This question is part of the following fields:
- Embryology
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Question 10
Incorrect
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Which one of the following changes are in the correct sequence regarding female puberty?
Your Answer: Maximal growth velocity, thelarche, menarche
Correct Answer: Thelarche, maximal growth velocity, menarche
Explanation:Thelarche means appearance of the breast tissue under the influence of oestrogen from the ovaries. It heralds the onset of puberty among girls. It is followed by an increase in growth velocity followed by menarche which is the time of first menstrual bleeding.
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This question is part of the following fields:
- Embryology
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Question 11
Incorrect
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Regarding feto-maternal blood circulation, which of the following statements is false?
Your Answer: In the umbilical vein the pressure is approximately 20 mmHg
Correct Answer: At term the placenta receives 70% of uterine blood flow
Explanation:The placenta is important for regulating feto-maternal blood circulation, ensuring that the two circulatory systems do not come into direct contact. The placenta receives 70-80% of the uterine blood flow into the decidual spiral arteries where nutrient, waste and gaseous exchange with fetal blood takes place via the villous core fetal vessels. Deoxygenated blood arrives at the placenta via two uterine arteries while oxygenated, nutrient-rich blood is circulated back to the foetus via a single umbilical vein. The pressure in the umbilical vein is about 20 mmHg.
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This question is part of the following fields:
- Embryology
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Question 12
Correct
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Question 13
Incorrect
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Question 14
Correct
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Question 15
Incorrect
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Which one of the following statements is related to testicular feminization syndrome?
Your Answer: There's usually very low testosterone levels
Correct Answer: There are usually normal testes
Explanation:Androgen insensitivity (testicular feminization) syndrome is a rare inherited form of male pseudo hermaphroditism that occurs in phenotypically normal women with adequate breast development, normal external genitalia, a vagina of variable depth, absent uterus, and sparse or absent pubic hair and axillary hair. Testosterone levels are normal or elevated.
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This question is part of the following fields:
- Embryology
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Question 16
Correct
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Question 17
Correct
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In fetal circulation:
Your Answer: Most of the blood entering the right atrium flows into the left atrium
Explanation:Circulation in the foetus: 1. Deoxygenated fetal blood is conducted to the placenta via the two umbilical arteries. The umbilical arteries arise from the internal iliac arteries.
2. Gas exchange occurs in placenta.
3. Oxygenated blood from the placenta passes through the single umbilical vein and enters the inferior vena cava (IVC).
4. About 50% of the blood in the IVC passes through the liver and the rest bypasses the liver via the ductus venosus. The IVC also drains blood returning from the lower trunk and extremities.
5. On reaching the heart, blood is effectively divided into two streams by the edge of the interatrial septum (crista dividens) (1) a larger stream is shunted to the left atrium through the foramen ovale (lying between IVC and left atrium) (2) the other stream passes into right atrium where it is joined by blood from SVC which is blood returning from the myocardium and upper parts of body. This stream therefore has a lower partial pressure of oxygen.
6. Because of the large pulmonary vascular resistance and the presence of the ductus arteriosus most of the right ventricular output passes into the aorta at a point distal to the origin of the arteries to the head and upper extremities. The diameter of the ductus arteriosus is similar to the descending aorta. The patency of the ductus arteriosus is maintained by the low oxygen tension and the vasodilating effects of prostaglandin E2;
7. Blood flowing through the foramen ovale and into left atrium passes into the left ventricle where it is ejected into the ascending aorta. This relatively oxygen rich blood passes predominantly to the head and upper extremities. -
This question is part of the following fields:
- Embryology
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Question 18
Incorrect
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While evaluating a 33-year-old woman for infertility, you diagnose a bicornuate uterus. You explain that additional testing is necessary because of the woman's increased risk of congenital anomalies in which system?
Your Answer: Central nervous
Correct Answer: Urinary
Explanation:Bicornuate uterus is associated with an increased chance of urinary tract anomalies. Urinary tract anomalies were present in about 23.6% of cases of bicornuate uterus patients.
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This question is part of the following fields:
- Embryology
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Question 19
Correct
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The external carotid artery develops from which pharyngeal arch?
Your Answer: 1st
Explanation:The maxillary arteries and the external carotid arteries develop from the first pharyngeal arch. The stapedial arteries arise from the second, the common carotid artery and the internal carotid arteries from the third and the arch of the aorta and the right subclavian artery from the forth arch.
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This question is part of the following fields:
- Embryology
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Question 20
Correct
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All of the following complications can be found in a pregnant patient with a bicornuate uterus, except?
Your Answer: Polyhydramnios
Explanation:Women with a bicornuate uterus are at increased risk of recurrent abortions, premature birth, fetal malpositioning, placenta previa and retained products of placenta leading to post partum haemorrhage.
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This question is part of the following fields:
- Embryology
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