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Question 1
Correct
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Regarding the closure of the ductus arteriosus (DA) after birth which of the following most accurately describes the mechanisms leading to closure of the DA?
Your Answer: Increased arterial pO2, increased bradykinin & decreased Prostaglandin E2
Explanation:Normal closure of the ductus arteriosus (DA) is brought about by a number of mechanisms. Upon delivery the new born babies first breath inflates the lungs and this causes a rise in pO2. Oxygen is known to cause constriction of the DA in vivo and in vitro. In addition the decreased vascular resistance means the pressure within the lumen of the DA drops aiding closure. In addition on inflation of the lungs, the lungs produce bradykinin which stimulates smooth muscle constriction of the ductus. The most important factor is thought to be the drop in Prostaglandin E2. Prostaglandin E2 maintains patency of the Ductus in the unborn child but after birth is metabolised in the lungs and its levels fall rapidly within 3 hours of birth.
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This question is part of the following fields:
- Embryology
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Question 2
Correct
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The second meiotic division of the oocyte is normally completed:
Your Answer: After the sperm penetrates the secondary oocyte
Explanation:Upon penetration, if all is normally occurring, the process of egg-activation occurs, and the oocyte is said to have become activated. This is thought to be induced by a specific protein phospholipase c zeta. It undergoes its secondary meiotic division, and the two haploid nuclei (paternal and maternal) fuse to form a zygote.
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This question is part of the following fields:
- Embryology
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Question 3
Correct
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Question 4
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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Question 5
Correct
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Regarding feto-maternal blood circulation, which of the following statements is false?
Your 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 6
Correct
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How many days after fertilisation does the blastocyst form?
Your 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 7
Incorrect
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Regarding the closure of the ductus arteriosus (DA) after birth which of the following most accurately describes the mechanisms leading to closure of the DA?
Your Answer: Increased arterial pO2, increased bradykinin & increased Prostaglandin E2
Correct Answer: Increased arterial pO2, increased bradykinin & decreased Prostaglandin E2
Explanation:Functional closure of the ductus arteriosus is neonates is completed within the first few days after birth. It normally occurs by the 12th postnatal week. It has been suggested that persistent patency of DA results from a failure of the TGF-B induction after birth. Due to increased arterial pO2, constriction of the DA occurs. In addition to this on inflation the bradykinin system is activated with cause the smooth muscles in the DA to constrict. A decrease in the E2 prostaglandin is also an important factor as raised levels have been indicated in keeping the patency of the DA.
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This question is part of the following fields:
- Embryology
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Question 8
Correct
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Several mechanisms have been proposed as to what causes closure of the Ductus Arteriosus (DA) at Parturition. Which of the following is the most important in maintaining the patency of the DA during pregnancy?
Your Answer: PGE2
Explanation:Prostaglandin E1 and E2 help maintain the patency of the DA during pregnancy. PGE2 is by far the most potent and important. It is produced in large quantities by the placenta and the DA itself.
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This question is part of the following fields:
- Embryology
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Question 9
Correct
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From which germ cell layer does the GI tract initially develop?
Your Answer: Endoderm
Explanation:The GI tract forms from the endoderm. The endoderm grows laterally and then ventrally finally folding on its self to form the gut tube.
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This question is part of the following fields:
- Embryology
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Question 10
Correct
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Which of the following statements is FALSE regarding Turner's syndrome?
Your Answer: Buccal smear is chromatin positive
Explanation:Turner syndrome patients have high FSH levels and low oestrogen levels. They have a short stature and buccal smear is chromatin negative.
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This question is part of the following fields:
- Embryology
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Question 11
Correct
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Turner's syndrome is characterised by :
Your Answer: Streak ovaries
Explanation:Turner syndrome, a condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects. Streak ovaries are a form of ovarian dysgenesis and are associated with Turner syndrome. Occasionally they may be functional and secondary sexual characteristics may develop.
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This question is part of the following fields:
- Embryology
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Question 12
Correct
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All of the following are features of Turner's syndrome except:
Your Answer: The ovaries are usually well developed
Explanation:Turner syndrome patients have malfunctioning or streak ovaries due to which they can never conceive. It affects females, who will have a short stature, widely spaced nipples, webbed neck and karyotyping shows 45XO.
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This question is part of the following fields:
- Embryology
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Question 13
Incorrect
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Normal physiological gut herniation occurs at how many weeks gestation?
Your Answer: 12 weeks
Correct Answer: 8 weeks
Explanation:At about 8-12 weeks gestation, normal physiological herniation of the fetal bowel occurs. The midgut protrudes into the base of the umbilicus, and undergoes a 90-degree anticlockwise rotation. When the abdominal cavity enlarges enough to fit the developing midgut, the intestines undergo another 180-degree rotation before returning to the abdominal cavity.
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This question is part of the following fields:
- Embryology
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Question 14
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 15
Correct
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Which one of the following statements is true regarding androgen insensitivity syndrome?
Your Answer: They have no uterus
Explanation:Androgen insensitivity syndrome means that patients are phenotypically males but they are resistant or insensitive to male androgen hormones. They do not have a uterus. Due to insensitivity to androgens these patients often have female traits but their genetic makeup is of male, 46XY.
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This question is part of the following fields:
- Embryology
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Question 16
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 17
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:Blood enters the right atrium of the fetal heart and most passes through the foramen ovale into the left atrium. From there it is pumped through the aorta. The foramen ovale is the major structure for bypassing the fetal pulmonary circulation. Some of the blood in the right atrium does enters the right ventricle and then into the pulmonary artery however most of this passes through the ductus arteriosus into the aorta thus bypassing the fetal pulmonary circulation.
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This question is part of the following fields:
- Embryology
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Question 18
Correct
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Which pharyngeal arch is closest to the head of the embryo?
Your Answer: 1st
Explanation:The arches are numbered according to their proximity to the head i.e. the 1st is the closest to the head end of the embryo and the 6th closest to the tail end as shown by the diagram below the table
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This question is part of the following fields:
- Embryology
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Question 19
Correct
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What is the life span of the corpus luteum in days?
Your Answer: 14-16
Explanation:After the release of the oocyte, the theca and the granulosa cells form the corpus luteum which undergoes extensive vascularization for continued steroidogenesis. Progesterone is secreted by the luteal cells and is synthesized from cholesterol. The luteal phase lasts for 14 days and if implantation does not occurs the corpus luteum starts to degenerate. As B-HCG produced by the implanted embryo maintains it and without it luteolysis occurs.
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This question is part of the following fields:
- Embryology
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Question 20
Correct
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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: 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 21
Correct
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From which germ layer does the myenteric plexus of the GI tract developed:
Your Answer: Neural crest of Ectoderm
Explanation:During the 5th week, the neural crest cells migrate along each side of the spinal cord where they form ganglions located dorsolateral to the aorta. Some of these cells migrate ventrally and form neurons in the preaortic ganglia as the celiac and mesenteric ganglia.
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This question is part of the following fields:
- Embryology
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Question 22
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 23
Incorrect
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Question 24
Correct
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Which one of the following statements regarding Turner's syndrome is true?
Your Answer: Usually presents with primary amenorrhea
Explanation:Turner syndrome patients present with primary amenorrhea, have non functional or streak ovaries and cant conceive. They are 45X genetically.
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This question is part of the following fields:
- Embryology
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Question 25
Correct
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Which one of the following features is associated with Turner's syndrome?
Your Answer: Primary amenorrhea
Explanation:Turner syndrome patients present with primary amenorrhea. These ladies have non functional or streak ovaries and they cant conceive. Their genetic traits is 45X. They have a shielded chest, webbed neck and low height. These patients suffer from primary amenorrhea.
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This question is part of the following fields:
- Embryology
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Question 26
Correct
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Which one of the following statements is related to testicular feminization syndrome?
Your 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 27
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 28
Incorrect
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In a non-ovulating follicle, follicular growth is followed by:
Your Answer: Regression
Correct Answer: Atresia
Explanation:During the ovulatory cycle, only one follicle will ovulate. The remaining non-ovulating follicles undergo disintegration. This process is known as atresia.
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This question is part of the following fields:
- Embryology
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Question 29
Incorrect
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Question 30
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 31
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 32
Correct
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Androgen insensitivity syndrome is characterised by which one of the following karyotypes?
Your Answer: 46XY
Explanation:Genetically, patients suffering from androgen insensitivity syndrome are 46XY. They are males but insensitive to male hormones i.e. androgens.
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This question is part of the following fields:
- Embryology
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Question 33
Incorrect
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Regarding implantation, how many days after fertilisation does it typically occur?
Your Answer: 5
Correct Answer: 8
Explanation:Fertilization usually occurs in the fallopian tubes after ovulation. The zygote moves through the fallopian tube and implants in the endometrium about 7-9 days after fertilisation, or 6-12 days after ovulation.
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This question is part of the following fields:
- Embryology
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Question 34
Correct
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A 15 year old girl is being investigated for primary amenorrhoea. She has normal FSH,LH and E2 levels on hormone profiling and normal secondary sexual characteristics. An ultrasound shows no uterus. What is the likely diagnosis?
Your Answer: Rokitansky-Kuster-Hauser syndrome
Explanation:Mullerian agenesis occurs in 1 in 5000 to 1 in 40000 girls. The Mullerian system does not develop which results in an absent uterus and upper vagina. This condition is also known as Rokitansky-Kuster-Hauser syndrome, The ovarian function is normal and so the most common presentation is amenorrhea in the presence of an otherwise normal pubertal development.
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This question is part of the following fields:
- Embryology
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Question 35
Correct
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Question 36
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 37
Incorrect
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How many days after fertilisation does the morula form?
Your Answer: 2
Correct Answer: 4
Explanation:When there are about 12-32 blastomeres, the developing human is referred to as morula. It enters the uterine cavity around the 4th day after fertilization.
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This question is part of the following fields:
- Embryology
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Question 38
Correct
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Question 39
Correct
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At birth, approximately how many oocytes are present in the ovaries?
Your Answer: 1 million
Explanation:Female infants are thought to be born with the total number of gametes they will posses in their lifetime. About 1 million healthy oocytes are present at birth. However, only about 300,000 of these oocytes survive to puberty, a number which continues to decline until all the oocytes are depleted triggering menopause.
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This question is part of the following fields:
- Embryology
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Question 40
Correct
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Which one of the following statements is true regarding the development of external genitalia?
Your Answer: The genital fold forms the scrotum in males
Explanation:Genital folds lead to the formation of the scrotum in males while in females they form the posterior labial commissure. Genital tubercles form the labia majora whereas the tubercle itself becomes the mons pubis. The labia minora is formed by the urogenital folds.
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This question is part of the following fields:
- Embryology
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Question 41
Correct
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From which germ cell layer does the GI tract initially develop?
Your Answer: Endoderm
Explanation:GI Tract initially forms via gastrulation from the endoderm of the trilaminar embryo around week 3. It extends from the buccopharyngeal membrane to the cloacal membrane. Later in development there are contributions from all three germ cell layers.
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This question is part of the following fields:
- Embryology
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Question 42
Correct
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Which one of the following changes are in the correct sequence regarding female puberty?
Your 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 43
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 44
Correct
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Question 45
Correct
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All of the following may result from a bicornuate uterus except:
Your Answer: Congenital anomalies of the baby
Explanation:Literature review shows that bicornuate uterus is associated with increase risk of spontaneous abortion in about 36% of patients. There is also an increased risk of preterm birth, malpresentation and fetal growth retardation.
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This question is part of the following fields:
- Embryology
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Question 46
Correct
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Which one of the following statements best suits Androgen insensitivity syndrome?
Your Answer: Gonadectomy must be performed after puberty because of the increased risk of malignancy
Explanation:Androgen insensitivity syndrome patients have 46XY chromosomes. They are males by genotype but appear as female because of insensitivity to male hormones. It is advisable to perform gonadectomy in these patients after puberty because these patients are at increased risk of developing malignancy.
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This question is part of the following fields:
- Embryology
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Question 47
Correct
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A Bicornuate uterus is due to which of the following?
Your Answer: Abnormal fusion and reabsorption of the paramesonephric ducts
Explanation:A Bicornuate uterus (heart shaped) is the result of abnormal fusion and reabsorption of the paramesonephric ducts during embryogenesis. Mullerian agenesis typically results in failure to form a uterus. Mullerian duct fusion abnormalities can cause a bicornuate malformation. PKD-1 gene abnormalities are associated with PCOS. Crossed fused ectopia result in Horseshoe kidney.
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This question is part of the following fields:
- Embryology
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Question 48
Correct
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Ootidogenesis refers to which process during Oogenesis?
Your Answer: 1st and 2nd Meiotic Divisions
Explanation:Oogonium become Primary Oocyte via Growth/Maturation. This process is called oocytogenesis Primary Oocyte undergoes 2 meiotic divisions to become Ootids. This process is called Ootidogenesis Ootids differentiate into Ovum
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This question is part of the following fields:
- Embryology
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Question 49
Correct
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Question 50
Correct
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Several mechanisms have been proposed as to what causes closure of the Ductus Arteriosus (DA) at Parturition. Which of the following is the most important in maintaining the patency of the DA during pregnancy?
Your Answer: PGE2
Explanation:Functional closure of the ductus arteriosus is neonates is completed within the first few days after birth. It normally occurs by the 12th postnatal week. It has been suggested that persistent patency of DA results from a failure of the TGF-B induction after birth. Due to increased arterial pO2, constriction of the DA occurs. In addition to this on inflation the bradykinin system is activated with cause the smooth muscles in the DA to constrict. A decrease in the E2 prostaglandin is also an important factor as raised levels have been indicated in keeping the patency of the DA.
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This question is part of the following fields:
- Embryology
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SESSION STATS - PERFORMANCE PER SPECIALTY
