Embryology and Development — MCQs
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Which tumor is shown here?
Which of the following statements with regard to Meckel's Diverticulum are correct? 1. It represents a persistent remnant of the vitellointestinal duct. 2. It is a true diverticulum of gastrointestinal tract. 3. It is most commonly found on anti-mesenteric border of ileum. 4. Heterotopic mucosa is present in 50-60% of patients. Select the correct answer using the code given below:
Which of the following statements regarding annular pancreas is INCORRECT? 1. It results from failure of rotation of ventral pancreatic bud during development. 2. A ring of pancreatic tissue surrounds the second or third part of duodenum. 3. It presents with vomiting due to duodenal obstruction. 4. Duodenoduodenostomy is the preferred treatment of this condition.
The commonest site for thyroglossal cyst is :
A meningomyelocele is most commonly situated in the
Before puberty, what is the ratio between the cervical length and uterine body?
The lungs are derived from an out-pouching of the primitive foregut during which period of intrauterine life?
Regarding “conjoined twins”, which of the following statements is/are true? 1. These are always monozygotic 2. These result when division occurs before the embryonic disc is formed 3. Most common variety is thoracopagus Select the correct answer using the code given below:
The umbilical cord normally contains:
The external opening of branchial fistula is present in :
Embryology and Development Indian Medical PG Practice Questions and MCQs
Question 1001: Which tumor is shown here?
- A. Sacrococcygeal teratoma (Correct Answer)
- B. Meningocele
- C. Chloroma
- D. Infantile fibrosarcoma
Explanation: **Sacrococcygeal teratoma** - The image shows a **large, complex mass** originating from the **sacrococcygeal region** of an infant, a classic presentation for a sacrococcygeal teratoma. - These tumors are typically **congenital germ cell tumors** and can be external, internal, or mixed, often presenting as a large visible mass at birth. *Meningocele* - A meningocele is a **protrusion of the meninges** through a defect in the spine, forming a sac filled with cerebrospinal fluid, but not containing neural tissue. - While it occurs in a similar anatomical region, a meningocele would appear as a **fluid-filled sac without the solid and sometimes hemorrhagic components** seen in the image. *Chloroma* - A chloroma (also known as a granulocytic sarcoma) is an **extramedullary tumor composed of myeloid blast cells**, typically associated with acute myeloid leukemia. - It usually presents as a discrete mass in various body sites, but its appearance is **rarely a large, malformed growth from the sacrococcygeal region** in an infant, and it usually has a greenish hue due to myeloperoxidase. *Infantile fibrosarcoma* - Infantile fibrosarcoma is a **malignant soft tissue tumor** that can occur in infants, often presenting as a rapidly growing mass. - While it can occur in various locations, the **distinctive appearance of a complex, mixed-tissue mass** in the sacrococcygeal area is more characteristic of a teratoma than a purely mesenchymal tumor like fibrosarcoma.
Question 1002: Which of the following statements with regard to Meckel's Diverticulum are correct? 1. It represents a persistent remnant of the vitellointestinal duct. 2. It is a true diverticulum of gastrointestinal tract. 3. It is most commonly found on anti-mesenteric border of ileum. 4. Heterotopic mucosa is present in 50-60% of patients. Select the correct answer using the code given below:
- A. 1, 3 and 4
- B. 1, 2 and 4
- C. 1 and 3
- D. 1, 2 and 3 (Correct Answer)
Explanation: ***Option: 1, 2 and 3 (Correct Answer)*** - **Statement 1 is correct:** Meckel's diverticulum is a **congenital anomaly** resulting from incomplete obliteration of the **vitellointestinal (vitelline) duct**, which connects the midgut to the yolk sac during embryonic development [1]. - **Statement 2 is correct:** It is a **true diverticulum** because it contains all three layers of the intestinal wall: mucosa, submucosa, and muscularis propria (unlike false diverticula which only contain mucosa and submucosa). - **Statement 3 is correct:** It arises from the **anti-mesenteric border of the ileum**, typically within 60-100 cm proximal to the ileocecal valve [1]. - **Statement 4 is incorrect:** Heterotopic mucosa (most commonly gastric mucosa, followed by pancreatic tissue) is present in approximately **20-30% of all Meckel's diverticula**. The 50-60% figure applies specifically to **symptomatic cases**, not all patients with the condition [1]. *Option: 1, 3 and 4* - While statements 1 and 3 are correct, statement 4 overstates the prevalence of heterotopic mucosa in the general population with Meckel's diverticulum [1]. - Additionally, this option excludes statement 2, which is definitively correct and represents an essential characteristic of Meckel's as a true diverticulum. *Option: 1, 2 and 4* - Statements 1 and 2 are correct, but statement 4's percentage for heterotopic mucosa (50-60%) is too high for the overall population [1]. - The actual prevalence of heterotopic mucosa is **20-30% in all cases**, though it is found in the majority of symptomatic presentations. *Option: 1 and 3* - While statements 1 and 3 are correct, this option incorrectly excludes statement 2. - Statement 2 is unequivocally correct: Meckel's is a **true diverticulum** with all intestinal wall layers, which distinguishes it from false diverticula.
Question 1003: Which of the following statements regarding annular pancreas is INCORRECT? 1. It results from failure of rotation of ventral pancreatic bud during development. 2. A ring of pancreatic tissue surrounds the second or third part of duodenum. 3. It presents with vomiting due to duodenal obstruction. 4. Duodenoduodenostomy is the preferred treatment of this condition.
- A. 4. Duodenoduodenostomy is the preferred treatment of this condition. (Correct Answer)
- B. 3. It presents with vomiting due to duodenal obstruction.
- C. 1. It results from failure of rotation of ventral pancreatic bud during development.
- D. 2. A ring of pancreatic tissue surrounds the second part of duodenum.
Explanation: ***Correct Answer: 4. Duodenoduodenostomy is the preferred treatment of this condition.*** - This statement is **INCORRECT** and hence the correct answer to this question. - The preferred surgical treatment for symptomatic annular pancreas is a **bypass procedure** such as **duodenojejunostomy** or **gastrojejunostomy**, NOT duodenoduodenostomy. [1], [3] - The goal is to **relieve duodenal obstruction** without resecting pancreatic tissue, which carries high risk of complications including pancreatitis and pancreatic fistula. *Incorrect Option 1: It results from failure of rotation of ventral pancreatic bud during development.* - This statement is **correct**. - Annular pancreas is a rare **congenital anomaly** caused by abnormal **rotation and fusion of the ventral pancreatic bud** with the dorsal bud during embryonic development, resulting in pancreatic tissue encircling the duodenum. *Incorrect Option 2: A ring of pancreatic tissue surrounds the second or third part of duodenum.* - This statement is **correct**. - Annular pancreas is characterized by a **ring of pancreatic tissue** that encircles the **second part of the duodenum** (most commonly), though the third part can occasionally be involved. *Incorrect Option 3: It presents with vomiting due to duodenal obstruction.* - This statement is **correct**. - The classic presentation includes **vomiting due to duodenal obstruction**, which can be complete or partial. [2] - In neonates, this manifests as **bilious vomiting** and feeding intolerance; in adults, postprandial fullness and recurrent vomiting are common. [2]
Question 1004: The commonest site for thyroglossal cyst is :
- A. Submentum
- B. Subhyoid (Correct Answer)
- C. Suprahyoid
- D. Foramen caecum
Explanation: ***Subhyoid (Infrahyoid)*** - The **subhyoid (infrahyoid) region** is the most common location for thyroglossal cysts, accounting for **50-65% of cases**. - The thyroglossal duct passes through or is intimately related to the **body of the hyoid bone** during embryonic descent of the thyroid gland from the foramen cecum [1], [2]. - Cysts most frequently form **at or just below the level of the hyoid bone** in the midline neck. - These cysts characteristically **move upward with swallowing and tongue protrusion** due to their attachment to the hyoid bone. *Suprahyoid* - Suprahyoid cysts occur **above the hyoid bone** and account for approximately **20-25% of cases**. - While common, they are **less frequent than subhyoid cysts**. - These may present higher in the neck but still maintain the characteristic midline location. *Submentum* - The submental region is **anterior and superior to the hyoid bone** in the midline. - Thyroglossal cysts in this location are **uncommon** as the duct's path runs more posteriorly in relation to this space. - True submental cysts are rare and must be differentiated from dermoid cysts. *Foramen caecum* - This is the **embryological origin** of the thyroglossal duct at the base of the tongue [1], [2]. - Cysts at this location are called **lingual thyroglossal cysts** and are very rare (1-2% of cases) [1]. - They present as tongue base masses and can cause dysphagia or airway obstruction.
Question 1005: A meningomyelocele is most commonly situated in the
- A. Thoracic spine
- B. Dorsolumbar spine
- C. Cervical spine
- D. Lumbosacral spine (Correct Answer)
Explanation: ***Lumbosacral spine*** - The **lumbosacral region** (L5-S1) is the most frequent anatomical site for meningomyelocele due to the timing of neural tube closure. - This area is the last portion of the **neural tube** to close, making it more susceptible to defects if closure is incomplete [1]. *Thoracic spine* - While meningomyeloceles can occur in the thoracic region, it is far less common than in the lumbosacral area [1]. - Defects in the thoracic spine are usually associated with a higher level of neurological impairment [1]. *Dorsolumbar spine* - This term encompasses the lower thoracic and upper lumbar regions; while possible, it is not the most common singular site. - The lumbosacral region has a higher prevalence of meningomyelocele formation. *Cervical spine* - Meningoceles and meningomyeloceles in the cervical spine are much rarer. - These defects often present with different neurological findings compared to lumbosacral lesions, such as upper limb weakness.
Question 1006: Before puberty, what is the ratio between the cervical length and uterine body?
- A. 1 : 2
- B. 2 : 1 (Correct Answer)
- C. 1 : 3
- D. 1 : 4
Explanation: **2:1 (Correct Answer)** - Before puberty, the **cervix** is proportionally much longer than the **uterine body**, with a typical ratio of 2:1 (cervix:body) [1]. - This anatomical ratio changes significantly after puberty due to hormonal influences causing the uterine body to grow more rapidly. *1:2 (Incorrect)* - This ratio of 1:2, where the uterine body is longer than the cervix, is characteristic of the **post-pubertal** and **reproductive years** [1]. - It reflects the increased growth and development of the uterine corpus under the influence of hormones like **estrogen**. *1:3 (Incorrect)* - This ratio is not typical at any stage of uterine development, as the uterine body generally does not become three times the length of the cervix. - It represents an **unusual disproportion** in uterine-cervical length. *1:4 (Incorrect)* - This ratio is also not a standard physiological proportion for uterine-cervical length at any developmental stage. - Such an extreme disproportion would likely indicate an **anomalous uterine development**.
Question 1007: The lungs are derived from an out-pouching of the primitive foregut during which period of intrauterine life?
- A. 3rd week
- B. 5th week
- C. 4th week (Correct Answer)
- D. 6th week
Explanation: ***4th week*** - The **respiratory diverticulum (lung bud)** appears as a ventral out-pouching from the **primitive foregut** at approximately **26-28 days** of development, which falls in the **4th week** of intrauterine life [1]. - This marks the beginning of the respiratory system's development, initiating the formation of the **larynx**, **trachea**, **bronchi**, and **lungs** [1]. - The lung bud forms from the foregut endoderm and subsequently divides into the **right and left bronchial buds**. *3rd week* - During the third week, **gastrulation** occurs with the formation of the three germ layers (ectoderm, mesoderm, endoderm). - The **primitive gut tube** begins to form toward the end of the third week through **lateral and cranio-caudal folding**, but the respiratory diverticulum has not yet appeared. - The lung bud out-pouching occurs later, around day 26-28 of the fourth week. *5th week* - By the fifth week, the **laryngotracheal tube** has separated from the foregut via the **tracheoesophageal septum**. - The main **bronchi** continue to elongate and branch into **secondary (lobar) bronchi**. - The initial formation of the lung bud precedes this developmental stage. *6th week* - By the sixth week, the **bronchial tree** undergoes further branching with the formation of **tertiary (segmental) bronchi**. - The **pseudoglandular stage** of lung development is underway, with continued airway differentiation. - This represents a later stage of respiratory development, well after the initial lung bud formation [1].
Question 1008: Regarding “conjoined twins”, which of the following statements is/are true? 1. These are always monozygotic 2. These result when division occurs before the embryonic disc is formed 3. Most common variety is thoracopagus Select the correct answer using the code given below:
- A. 1 and 2 only
- B. 2 and 3 only
- C. 1, 2 and 3
- D. 1 and 3 only (Correct Answer)
Explanation: ***1 and 3 only*** - **Identical (monozygotic)** twins are always conjoined because they develop from a single fertilized egg that imperfectly separates. - **Incomplete division** of the embryonic disc after 13 days from fertilization causes conjoined twins [1]. **Thoracopagus** is the most common type, where twins are joined at the chest [1, 2]. *1 and 2 only* - Conjoined twins are indeed **monozygotic**, but the timing of division is typically *after* the embryonic disc is formed, not before [1]. - Division *before* the embryonic disc forms would usually lead to separate monozygotic twins [1]. *2 and 3 only* - While **thoracopagus** is the most common variety [2], statement 2 regarding the timing of division is incorrect. - Conjoined twins are a result of incomplete separation *after* the formation of the embryonic disc, typically around 13-15 days post-fertilization [1]. *1, 2 and 3* - This option incorrectly states that division occurs *before* the embryonic disc is formed. - The formation of conjoined twins results from an *incomplete* splitting of the **monozygotic embryo** *after* the embryonic disc has already begun to differentiate [1].
Question 1009: The umbilical cord normally contains:
- A. One artery and two veins
- B. One artery and one vein
- C. Two arteries and two veins
- D. Two arteries and one vein (Correct Answer)
Explanation: ***Two arteries and one vein*** - The umbilical cord typically contains **two umbilical arteries** [1] that carry deoxygenated blood and waste products from the fetus to the placenta. - It also contains **one umbilical vein** [2, 3] that carries oxygenated, nutrient-rich blood from the placenta to the fetus. - This is the **normal anatomical configuration** of the umbilical cord. *One artery and two veins* - This configuration is **incorrect** as there is only **one umbilical vein** [2] in the normal umbilical cord, not two. - The presence of a single artery (single umbilical artery - SUA) is a recognized anomaly associated with certain fetal abnormalities, but even in SUA, there is only one vein. *One artery and one vein* - This arrangement is **incorrect** as the normal umbilical cord contains **two arteries**, not one [1]. - Single umbilical artery (SUA) is the most common umbilical cord anomaly, occurring in about 1% of pregnancies, but this is still an abnormal finding. *Two arteries and two veins* - This statement is **incorrect** because the normal umbilical cord contains only **one umbilical vein**, not two. - The presence of two veins would be a rare anomaly and is not part of normal umbilical cord anatomy.
Question 1010: The external opening of branchial fistula is present in :
- A. Middle third of the neck
- B. Lower third of the neck (Correct Answer)
- C. Upper third of the neck
- D. Suprasternal notch
Explanation: ***Lower third of the neck*** - The external opening of a branchial fistula is typically found in the **lower third of the anterolateral neck**, anterior to the sternocleidomastoid muscle [1]. - This location corresponds to the embryological remnants of the second branchial cleft failing to close completely. *Middle third of the neck* - While other branchial anomalies might present in the middle third, the classic external opening of a **branchial fistula** is usually lower [1]. - Cysts (branchial cleft cysts) are more commonly found in the middle third [1]. *Upper third of the neck* - Anomalies in the upper third of the neck are less common for an external branchial fistula opening. - This region is more associated with anomalies of the first branchial cleft [1]. *Suprasternal notch* - The suprasternal notch is located at the base of the neck, and while cysts can occur in this area (e.g., cervicomediastinal thymic cysts), it is not the typical site for a **branchial fistula** opening. - This location is often associated with abnormalities of thyroid development or other midline defects.
Practice by Chapter
Gametogenesis and Fertilization
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Early Embryonic Development
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Placentation
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Development of Nervous System
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Development of Cardiovascular System
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Development of Gastrointestinal System
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Development of Urogenital System
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Development of Musculoskeletal System
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Development of Head and Neck
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Congenital Anomalies
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Teratology
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Molecular Mechanisms in Development
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