Embryology (General, Pharyngeal Arches, GUT, CNS, Cardiovascular) MCQs

Anatomy · 78 free questions with answers & explanations.

1. A newborn presents with a midline neck mass that moves upward on swallowing and on tongue protrusion. This is most likely a remnant of which embryological structure?
2. Derivatives of the third pharyngeal arch include which structures?
3. A neonate is found to have a cyanotic congenital heart disease with a single common arterial trunk arising from both ventricles. Failure of partitioning of which embryological structure causes this defect?
4. The notochord induces the overlying ectoderm to form the neural plate. This process is specifically termed:
5. The midgut normally herniates into the umbilical cord at the 6th week and returns to the abdomen by which week?
6. A newborn has a persistent truncus arteriosus. This defect arises primarily from failure of which embryological process?
7. A 3-day-old neonate has bilious vomiting, a 'double-bubble' sign on plain abdominal X-ray, and passes no meconium. Down syndrome is suspected. The anatomical basis of the double-bubble sign is:
8. A 2-year-old boy is found to have an ectopic thyroid gland at the base of the tongue (lingual thyroid). This represents failure of descent of the thyroid along which embryological path?
9. An infant is born with a wide-based, shuffling gait at 18 months, a prominent midline scalp mass that transilluminates, and a Chiari I malformation on MRI. The scalp mass is a meningocele through which structure?
10. A child is born with a defect where the aorta arises from the right ventricle and the pulmonary artery from the left ventricle (transposition of great arteries, D-TGA). This results from a defect in which embryological process?
11. In the embryo, the ductus venosus connects the umbilical vein to the inferior vena cava, allowing oxygenated placental blood to bypass the liver. What structure does it become in the adult?
12. A neonate is diagnosed with DiGeorge syndrome (22q11.2 deletion) presenting with hypocalcaemia, T-cell immunodeficiency, and conotruncal heart defects. What is the common embryological defect linking all these features?
13. A Meckel's diverticulum persists due to incomplete obliteration of the vitello-intestinal (omphalomesenteric) duct. Which of the following correctly describes its embryological and clinical characteristics?
14. The 3rd pharyngeal arch forms which specific structures in the adult?
15. Tetralogy of Fallot results from anterosuperior displacement of the conotruncal septum. Which of the four features is the PRIMARY anomaly from which the other three are consequential?
16. DiGeorge syndrome results from failure of development of the 3rd and 4th pharyngeal pouches. Which structure specifically fails to develop, leading to T-cell immunodeficiency?
17. Failure of the urorectal septum to fully divide the cloaca results in a persistent cloaca. The urorectal septum is formed by which embryonic process?
18. Hirschsprung's disease (congenital aganglionic megacolon) results from failure of neural crest cells to migrate to the hindgut. The aganglionic segment characteristically begins at the internal anal sphincter and extends proximally. The neural crest cells that fail to migrate arise from which region?
19. During cardiac embryology, the sinus venosus is initially a paired structure. Which sinus venosus-derived structure gives rise to the smooth part of the right atrium (sinus venarum)?
20. A neonate presents with hoarseness, aphonia, and absence of laryngeal and pharyngeal muscles on the right side. Embryologically, the muscles of the pharynx and larynx are derived from which pharyngeal arches, and this defect suggests failure of which arch's mesoderm to differentiate?
21. During cardiac embryology, the aorticopulmonary septum divides the truncus arteriosus in a spiral fashion. Failure of this spiral division leads to which congenital heart defect?
22. Meckel's diverticulum is the remnant of which embryological structure and is located at which distance and side of the ileum from the ileocaecal junction?
23. In neural tube closure defects, which signaling molecule produced by the notochord induces the overlying ectoderm to become neuroectoderm (neural plate), and what is the process called?
24. The derivatives of the second pharyngeal arch (Reichert's cartilage) include which of the following structures in the adult?
25. A neonate is found to have a persistent communication between the right and left atria after birth. If it is an ostium primum defect, which structure failed to develop correctly?
26. A newborn with DiGeorge syndrome has aplasia of the thymus and parathyroid glands. These structures are derived from which pharyngeal pouches?
27. A 2-day-old neonate presents with bilious vomiting and abdominal distension. Imaging shows a 'double bubble' sign. The embryological defect is failure of recanalization of the duodenum due to absence of which process?
28. Which vessel, present during fetal life, carries oxygenated blood from the placenta to the fetal systemic circulation and normally closes after birth to form the ligamentum teres hepatis?
29. Neural crest cells that migrate from the dorsal neural tube to the pharyngeal arches contribute to which structures?
30. A neonate is found to have a persistent truncus arteriosus (failure of division of the truncus into the aorta and pulmonary trunk). Which embryological cell population is primarily responsible for this division, and its migration defect accounts for this malformation?
31. A child is born with an anterior tongue that is covered by stratified squamous epithelium except for circumvallate papillae, which show a different epithelial lining. From which embryological structure does the posterior one-third of the tongue develop?
32. A newborn presents with intestinal atresia — the duodenum shows a 'double bubble' sign on abdominal X-ray. The second and third parts of the duodenum temporarily occlude during embryological development. Which process is responsible for re-canalization of the duodenal lumen?
33. A 25-year-old woman is found to have a midline fistula at the lower anterior neck that secretes mucoid fluid on swallowing. She has no signs of infection. This likely represents a patent thyroglossal duct. Surgical removal requires excision of which bone structure to prevent recurrence?
34. A neonate has a ventricular septal defect in the muscular (trabecular) part of the interventricular septum. The muscular septum develops by the upgrowth of which structure?
35. A newborn has a persistent thyroglossal duct cyst that becomes infected and drains through the skin at the midline of the neck. The cyst moves upward with protrusion of the tongue. The thyroid gland begins its descent from which embryological structure?
36. A fetus is found to have an atrial septal defect of the ostium secundum type. This defect results from failure of which embryological structure?
37. A baby is born with an imperforate anus and a rectovesical fistula. This malformation results from failure of which embryological structure to divide properly?
38. A child is born with a branchial cyst presenting as a mass at the anterior border of the sternocleidomastoid muscle. Embryologically, which pharyngeal structure gives rise to the second branchial cleft cyst?
39. A neonate has ductus arteriosus that failed to close. The ductus arteriosus is a remnant of which embryological structure?
40. A neonate presents with cyanosis that worsens with crying (paradoxically improves with feeding/crying). Echocardiography shows a single outlet vessel from the heart, with pulmonary arteries arising from the aorta. Failure of partitioning of which embryonic structure is responsible?
41. Tracheoesophageal fistula (TEF) with esophageal atresia is caused by a developmental error in the partitioning of the foregut. Which embryological structure forms abnormally to produce the most common type (Type C — proximal esophageal atresia with distal TEF)?
42. Meckel's diverticulum is a remnant of the vitello-intestinal (omphalomesenteric) duct. Which of the following statements about its anatomy is MOST accurate for NEET PG?
43. Neural tube defects (NTDs) are associated with folate deficiency. Which part of the neural tube is the LAST to close during normal neurulation, making it most vulnerable to defects?
44. In fetal circulation, well-oxygenated blood returning from the placenta via the umbilical vein bypasses the liver through a shunt directly into the inferior vena cava. What is this shunt and what does it become after birth?
45. A neonate presents with branchial cyst at the anterior border of the sternocleidomastoid muscle at the junction of the upper and middle thirds. This cyst is derived from which pharyngeal pouch/cleft and what epithelium lines it?
46. Persistent truncus arteriosus results from failure of which embryological process, and which mesenchymal structures are responsible for partitioning the primitive outflow tract?
47. Hirschsprung's disease (congenital aganglionic megacolon) results from failure of which embryological cell migration, and at what embryological week does this migration normally complete?
48. The thyroid gland develops from which embryological structure, and a thyroglossal duct cyst is found in the midline at what level in the majority of cases?
49. A male fetus has undescended testes at 32 weeks gestation. Testicular descent from the posterior abdominal wall to the scrotum occurs in two phases. Which hormone drives the second inguinoscrotal phase of descent?
50. In tetralogy of Fallot, one component is right ventricular hypertrophy (RVH), which is secondary. The primary defect causing all four features involves abnormal development of which structure?
51. The appendix of the testis (hydatid of Morgagni) is a remnant of which embryological structure?
52. Failure of closure of the neural tube at the caudal neuropore (day 26–28) results in which of the following?
53. Meckel's diverticulum is a remnant of the vitello-intestinal (omphalomesenteric) duct. It contains heterotopic gastric mucosa in approximately 50% of symptomatic cases. The RULE OF 2s for Meckel's diverticulum includes all EXCEPT:
54. In cardiovascular embryology, the truncus arteriosus is divided into the aorta and pulmonary trunk by the aorticopulmonary septum, which is derived from:
55. Failure of neural tube closure in the sacral region (caudal neuropore, normally closes by day 27) results in:
56. Which pharyngeal arch gives rise to the muscles of mastication and the tensor tympani muscle?
57. During gut rotation, the primary intestinal loop rotates counterclockwise around the superior mesenteric artery. By how many degrees and what is the final position of the cecum?
58. At birth, the ductus arteriosus closes functionally. Which mediator is responsible for its postnatal closure, and which agent keeps it patent antenatally?
59. Persistent truncus arteriosus results from failure of which developmental process?
60. The thyroid gland descends from the foramen caecum of the tongue to its final position in the neck, guided by the thyroglossal duct. Thyroglossal duct cysts characteristically move upward on swallowing and on protrusion of the tongue because:
61. Meckel's diverticulum represents a persistent remnant of the vitello-intestinal (omphalomesenteric) duct. It is located on the anti-mesenteric border of the ileum at what distance from the ileocaecal valve?
62. Failure of neural tube closure at the caudal neuropore (closes at ~day 27) results in which developmental anomaly?
63. In cardiovascular embryology, the septum primum grows from the roof of the common atrium toward the endocardial cushions. Before it fuses with the cushions, the gap between its free edge and the cushions is the foramen primum (ostium primum). Which event creates the foramen secundum and maintains right-to-left shunting?
64. A newborn presents with hypospadias, cryptorchidism, and bifid scrotum. Testing reveals 46,XY karyotype with a markedly elevated LH and testosterone but absent dihydrotestosterone (DHT). The likely embryological cause is:
65. The septum primum and septum secundum divide the primitive atrium. At birth, which event causes the functional closure of the foramen ovale?
66. Hirschsprung disease (congenital aganglionic megacolon) results from failure of neural crest cell migration. Which part of the bowel is always affected, and which neural crest population fails to complete migration?
67. The mesonephric (Wolffian) duct in the male fetus differentiates under the influence of testosterone into which adult structures?
68. During gut rotation, the primary intestinal loop (midgut) rotates a total of 270 degrees counterclockwise when viewed from the front. Non-rotation (absence of this rotation) typically results in which clinically important finding?
69. The ductus venosus shunts oxygenated umbilical venous blood directly into the IVC, bypassing the hepatic sinusoids. The ductus venosus is a derivative of which embryological vessel and becomes which adult ligament after birth?
70. Hirschsprung's disease results from failure of neural crest cell migration to colonize the hindgut. The aganglionic segment always begins at which part of the gut?
71. A newborn presents with a branchial (lateral cervical) cyst at the anterior border of sternocleidomastoid. This is most commonly derived from which pharyngeal pouch/groove?
72. A fetus is found to have absence of the septum primum and septum secundum. Which cardiac malformation results, and from what embryological failure?
73. A baby is born with the small intestine protruding through the umbilical ring covered by amnion but with the cord attached to the apex. This is an omphalocele. Which embryological event failed?
74. Persistent truncus arteriosus results from failure of which embryological process?
75. Treacher Collins syndrome (mandibulofacial dysostosis) results from abnormal development of which pharyngeal arch?
76. The ductus venosus connects which two structures in fetal circulation and allows blood to bypass the liver?
77. Failure of the midgut to return to the abdominal cavity during the 10th week of development results in:
78. During cardiac development, the aorticopulmonary septum (AP septum) divides the truncus arteriosus into the aorta and pulmonary trunk. Which cells migrate into the outflow tract to form this septum?