Embryology and Development — MCQs
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What is the embryological origin of the ligamentum arteriosum?
The trigone of urinary bladder is primarily derived from which germ layer?
What structures are derived from the neural crest?
Fibrous stroma of liver is derived from -
Which of the following is a derivative of paramesonephric duct in males ?
What does the ventral pancreatic duct give rise to?
Which of the following statements about the limbus fossa ovalis is false?
Which adult structure is derived from the posterior cardinal vein?
Superior vena cava develops from?
Which of the following statements about the notochord is false?
Embryology and Development Indian Medical PG Practice Questions and MCQs
Question 1111: What is the embryological origin of the ligamentum arteriosum?
- A. Remnant of the ductus arteriosus (Correct Answer)
- B. Remnant of the ductus venosus
- C. Remnant of the ductus utriculosaccularis
- D. Remnant of the ductus reuniens
Explanation: ***Remnant of the ductus arteriosus*** - The **ductus arteriosus** is a fetal blood vessel connecting the **pulmonary artery** to the **aorta**, bypassing the non-functional lungs [1]. - After birth, due to increased oxygen tension and decreased prostaglandins, it typically constricts and obliterates, forming the **ligamentum arteriosum** [2]. *Remnant of the ductus venosus* - The **ductus venosus** is a fetal shunt connecting the **umbilical vein** to the **inferior vena cava**, bypassing the liver's circulatory bed [2]. - After birth, it closes and becomes the **ligamentum venosum**, not the ligamentum arteriosum [2]. *Remnant of the ductus utriculosaccularis* - This is an **inner ear structure** connecting the utricle and saccule in the membranous labyrinth. - It is **not a cardiovascular structure** and has no relation to the ligamentum arteriosum. *Remnant of the ductus reuniens* - The **ductus reuniens** (also called ductus utriculosaccularis) is an **inner ear structure**, not a fetal cardiovascular shunt. - It has **no remnant** related to the ligamentum arteriosum or cardiovascular system.
Question 1112: The trigone of urinary bladder is primarily derived from which germ layer?
- A. Endoderm of urachus
- B. Mesoderm (Correct Answer)
- C. Ectoderm
- D. Endoderm of urogenital sinus
Explanation: ***Mesoderm*** - The trigone of the urinary bladder is primarily derived from the **mesoderm**, specifically from the caudal parts of the **mesonephric ducts** which are incorporated into the bladder wall [1]. - This mesodermal origin distinguishes it from the rest of the bladder, which is endodermal, and explains its histological difference [1]. *Ectoderm* - The ectoderm gives rise to structures like the **skin**, **nervous system**, and **sensory organs**, not internal urinary structures like the bladder trigone. - It is responsible for the formation of the **external genitalia** and the terminal part of the urethra, but not the bladder itself. *Endoderm of urachus* - The urachus is a remnant of the **allantois**, which is endodermal in origin, but it forms the **median umbilical ligament** and does not contribute to the trigone. - The main body of the bladder (excluding the trigone) is derived from the **endoderm of the cloaca**, but the trigone has a distinct mesodermal origin [1]. *Endoderm of urogenital sinus* - The urogenital sinus gives rise to the **main body of the bladder** (endodermal), but not the trigone [1]. - The trigone's mesodermal origin from the mesonephric ducts makes it histologically and embryologically distinct from the endoderm-derived bladder wall [1].
Question 1113: What structures are derived from the neural crest?
- A. Melanocytes
- B. Dental papillae
- C. Adrenal medulla
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The **neural crest** is a multipotent, migratory cell population that contributes to the formation of many diverse tissues and organs during vertebrate development. - Neural crest cells give rise to a wide array of derivatives, including components of the nervous system, pigment cells, skeletal and connective tissues of the head and face, and endocrine glands [1]. *Melanocytes* - **Melanocytes**, the pigment-producing cells found in the skin, hair, eyes, and other tissues, are derived from the **neural crest** [2]. - These cells migrate extensively during development from the neural crest to their final destinations throughout the body. - Neural crest-derived melanocytes produce melanin, which provides pigmentation and protection against UV radiation [2]. *Dental papillae* - The **dental papilla** is crucial for tooth development and is formed from **ectomesenchymal cells** that are derived from the cranial neural crest. - These cells differentiate into the odontoblasts that produce dentin and also contribute to the pulp of the tooth. *Adrenal medulla* - The cells of the **adrenal medulla**, which produce catecholamines like epinephrine and norepinephrine, are specialized **postganglionic sympathetic neurons** derived from the neural crest. - They develop from neuroectodermal cells that migrate to the developing adrenal gland.
Question 1114: Fibrous stroma of liver is derived from -
- A. Endoderm from the foregut
- B. Endoderm from the midgut
- C. Endoderm from the hindgut
- D. Mesoderm from the septum transversum (Correct Answer)
Explanation: ***Mesoderm from the septum transversum*** - The **fibrous stroma of the liver**, which provides its structural framework, develops from the **mesoderm** of the **septum transversum** [1]. - The septum transversum is a thick mass of mesoderm that contributes to the formation of the **diaphragm** and the connective tissue elements of the liver [1]. *Endoderm from the foregut* - While the **parenchymal cells (hepatocytes)** of the liver are derived from the **endoderm of the foregut**, this tissue forms the functional units, not the fibrous supporting stroma. - The endoderm forms the glandular tissue, while the mesoderm forms the connective tissue [1]. *Endoderm from the midgut* - The midgut endoderm gives rise to structures like the **small intestine**, cecum, appendix, ascending colon, and part of the transverse colon, but not the liver's stroma [2]. - Its primary role is in forming the epithelial lining of these digestive organs. *Endoderm from the hindgut* - The hindgut endoderm develops into the distal third of the transverse colon, descending colon, sigmoid colon, rectum, and superior part of the anal canal, - It plays no role in the development of the liver's fibrous stroma.
Question 1115: Which of the following is a derivative of paramesonephric duct in males ?
- A. Trigone of bladder
- B. Paraphoron
- C. Prostatic utricle (Correct Answer)
- D. Gartner's duct
Explanation: ***Prostatic utricle*** - The **prostatic utricle** is a blind-ending pouch located in the prostatic urethra. - It represents a **rudimentary derivative of the paramesonephric (Müllerian) duct** in males, which normally regresses due to the presence of Müllerian-inhibiting substance (MIS). *Trigone of bladder* - The trigone of the bladder is derived from the caudal ends of the **mesonephric ducts** (Wolffian ducts), not the paramesonephric ducts. - It forms through the incorporation of these ducts into the posterior wall of the bladder. *Paraphoron* - The **paraphoron** is a vestigial structure found in females, representing remnants of the caudal parts of the **epoophoron tubules**. - These are derived from the **mesonephric tubules**, not the paramesonephric ducts, and are not found in males. *Gartner's duct* - **Gartner's duct** is a remnant of the **mesonephric (Wolffian) duct** in females, typically running along the lateral wall of the vagina or uterus. - It is not found in males and is derived from a different embryonic structure than the paramesonephric duct.
Question 1116: What does the ventral pancreatic duct give rise to?
- A. Body
- B. Tail
- C. Neck
- D. Uncinate process (Correct Answer)
Explanation: ***Uncinate process*** - The **ventral pancreatic bud**, from which the ventral pancreatic duct originates, rotates posteriorly to fuse with the dorsal bud and gives rise to the **uncinate process** and part of the head of the pancreas [1]. - This developmental origin explains why the uncinate process is drained by the ventral pancreatic duct system [1]. *Body* - The **body of the pancreas** develops from the **dorsal pancreatic bud**, not the ventral bud [1]. - Its primary drainage is via the main pancreatic duct (of Wirsung), which is derived from the dorsal pancreatic duct. *Tail* - The **tail of the pancreas** also develops from the **dorsal pancreatic bud** and is located furthest from the duodenum [1]. - It drains into the main pancreatic duct system, reflecting its dorsal bud origin. *Neck* - The **neck of the pancreas** develops primarily from the **dorsal pancreatic bud**, although it is near the junction of the two buds [1]. - It forms part of the main body of the gland and drains via the main pancreatic duct.
Question 1117: Which of the following statements about the limbus fossa ovalis is false?
- A. Also called Annulus ovalis
- B. Derived from septum primum (Correct Answer)
- C. In right atrium
- D. Forms the rim around fossa ovalis
Explanation: ***Derived from septum primum*** - The **limbus fossa ovalis** (or annulus ovalis) is a structure in the right atrium that forms the prominent rim of the **fossa ovalis**. - It is derived from the inferior border of the **septum secundum**, not the septum primum, which primarily forms the floor of the fossa ovalis. *Forms the rim around fossa ovalis* - The **limbus fossa ovalis** is indeed the thickened, crescent-shaped border of tissue that surrounds the **fossa ovalis** in the interatrial septum. - This anatomical arrangement is a remnant of the **foramen ovale** from fetal circulation [1]. *In right atrium* - The **fossa ovalis** and its surrounding limbus are located on the septal wall of the **right atrium** [1]. - This position is crucial for its role as a key landmark in interatrial septum anatomy. *Also called Annulus ovalis* - The term **annulus ovalis** is a widely accepted synonym for the **limbus fossa ovalis**. - Both terms describe the same anatomical structure, the fibrous rim surrounding the fossa ovalis.
Question 1118: Which adult structure is derived from the posterior cardinal vein?
- A. Superior vena cava
- B. Internal jugular vein
- C. External jugular vein
- D. Azygos vein (Correct Answer)
Explanation: ***Azygos vein*** - The **posterior cardinal veins** are paired veins in the early embryo that undergo significant remodeling during development. - The **right posterior cardinal vein** contributes to the formation of the **azygos vein**, particularly its root and proximal portions. - During development, the posterior cardinal veins are largely replaced by the **supracardinal** and **subcardinal** venous systems, but the right posterior cardinal vein's caudal segment persists as part of the azygos system. - The azygos vein ultimately receives contributions from both posterior cardinal and supracardinal veins, making it the primary adult derivative among the given options. *Superior vena cava* - The **superior vena cava** is primarily derived from the right **anterior cardinal vein** and the **right common cardinal vein**. - It drains blood from the upper body and head but is not a derivative of the posterior cardinal venous system. *Internal jugular vein* - The **internal jugular veins** develop from the cranial portions of the **anterior cardinal veins**. - These veins drain the brain, face, and neck regions. *External jugular vein* - The **external jugular vein** develops from a venous plexus in the superficial neck structures. - It is not derived from the main cardinal venous systems but rather from superficial embryological vessels.
Question 1119: Superior vena cava develops from?
- A. Right anterior cardinal vein (Correct Answer)
- B. Left anterior cardinal vein
- C. Left common cardinal vein
- D. Right subcardinal vein
Explanation: Right anterior cardinal vein - The superior vena cava (SVC) forms from the right anterior cardinal vein and the common cardinal vein. - The right anterior cardinal vein directly contributes to the upper portion of the SVC. Left anterior cardinal vein - The left anterior cardinal vein typically regresses or becomes minor tributaries like the left SVC (if persistent) or the coronary sinus. - It does not form the main superior vena cava. Left common cardinal vein - The left common cardinal vein forms the coronary sinus and an oblique vein of the left atrium. - While major vessels drain into it, it does not directly form the superior vena cava. Right subcardinal vein - The right subcardinal vein is primarily involved in the development of the inferior vena cava (IVC), particularly its renal segment. - It does not contribute to the formation of the superior vena cava.
Question 1120: Which of the following statements about the notochord is false?
- A. Derived from hypoblast (Correct Answer)
- B. Serves as the primary inductor of the neural plate.
- C. Remains as the nucleus pulposus in adults.
- D. Defines axis of embryo
Explanation: ***Derived from hypoblast*** - The notochord is primarily derived from the **mesoderm** during gastrulation, specifically from cells migrating through the **primitive node** [1]. - The **hypoblast** contributes to the extraembryonic endoderm and the yolk sac, but not directly to the notochord itself [1]. *Defines axis of embryo* - The **notochord** establishes the main **cranio-caudal (anterior-posterior) axis** of the developing embryo. - Its presence is crucial for laying out the fundamental body plan and symmetry. *Serves as the primary inductor of the neural plate.* - The notochord secretes signaling molecules, such as **sonic hedgehog (Shh)**, which induce the overlying ectoderm to form the **neural plate**. - This inductive process is critical for the development of the central nervous system. *Remains as the nucleus pulposus in adults.* - While most of the notochord degenerates, remnants persist as the **nucleus pulposus** within the intervertebral discs. - The nucleus pulposus is the gelatinous core of the disc, providing flexibility and cushioning.
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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