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Question 1
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 2
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 3
Incorrect
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Question 4
Incorrect
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Branches V2 and V3 of the Trigeminal nerve develop from which pharyngeal arch?
Your Answer: 2nd
Correct Answer: 1st
Explanation:1st Arch = Trigeminal V2 & V3 (CN V) 2nd Arch = Facial (CN VII) 3rd Arch = Glossopharyngeal (CN IX) 4th and 6th Arches = Vagus (CN X)
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This question is part of the following fields:
- Embryology
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Question 5
Incorrect
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Which of the following statements is FALSE regarding Turner's syndrome?
Your Answer: High pituitary gonadotropin titre
Correct 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 6
Incorrect
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Which one of the following statements is true regarding androgen insensitivity syndrome?
Your Answer: Usually have secondary amenorrhea
Correct 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 7
Incorrect
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Regarding implantation, how many days after fertilisation does it typically occur?
Your Answer: 12
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 8
Correct
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Regarding fertilization & implantation:
Your Answer: The sperm head penetrates through the corona radiata & zona pellucida while the tail remains outside
Explanation:During fertilization, a sperm must first fuse with the plasma membrane and then penetrate the female egg cell to fertilize it. Fusing to the egg cell usually causes little problem, whereas penetrating through the egg’s hard shell or extracellular matrix can be more difficult. Therefore, sperm cells go through a process known as the acrosome reaction, which is the reaction that occurs in the acrosome of the sperm as it approaches the egg. The acrosome is a cap-like structure over the anterior half of the sperm’s head. 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. To prevent polyspermy and minimize the possibility of producing a triploid zygote, several changes to the egg’s cell membranes render them impenetrable shortly after the first sperm enters the egg.
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This question is part of the following fields:
- Embryology
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Question 9
Incorrect
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Question 10
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, decreased bradykinin & decreased Prostaglandin E1
Correct 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 11
Correct
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All of the following statements are true regarding Turner's syndrome except?
Your Answer: The streak ovaries should be removed surgically due to 25% tendency to be malignant
Explanation:Girls with Turner’s syndrome (45,X) are not at risk for malignancy. Patients with feminizing testicular syndrome with XY chromosome composition and patients with mixed gonadal dysgenesis are at risk for malignancy, and bilateral gonadectomy is performed.
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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 features are associated with congenital uterine malformations except:
Your Answer: Pregnancy induced hypertension
Explanation:Congenital uterine abnormalities are associated with an increased risk of spontaneous abortions, preterm delivery of the foetus, fetal growth retardation and malpresentation.
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This question is part of the following fields:
- Embryology
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Question 13
Incorrect
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From which germ cell layer does the GI tract initially develop?
Your Answer: Paraxial Mesoderm
Correct 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 14
Incorrect
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Which structure is the primary mechanism for shunting blood away from the fetal pulmonary circulation?
Your Answer: Ductus Arteriosus
Correct 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 15
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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Question 16
Incorrect
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Ootidogenesis refers to which process during Oogenesis?
Your Answer: Growth and maturation
Correct 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 17
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 18
Incorrect
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How many days after fertilisation does the blastocyst hatch from the zone pellucida?
Your Answer: 14-21
Correct 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 19
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 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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Question 21
Incorrect
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Question 22
Incorrect
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The external carotid artery develops from which pharyngeal arch?
Your Answer: 4th
Correct 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 23
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 24
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: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 25
Incorrect
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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: Complete Androgen Insensitivity Syndrome (CAIS)
Correct 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 26
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 27
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 28
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 29
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 30
Incorrect
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Regarding feto-maternal blood circulation, which of the following statements is false?
Your Answer: Deoxygenated fetal blood arrives at the placenta via 2 umbilical arteries
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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SESSION STATS - PERFORMANCE PER SPECIALTY
