Embryology and Development — MCQs
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The trigone of urinary bladder is primarily derived from which germ layer?
Superior vena cava develops from?
Which is the first bone to start ossifying?
Which of the following is a derivative of paramesonephric duct in males ?
Which of the following statements about the limbus fossa ovalis is false?
Tail of pancreas develops from -
What is the embryological origin of the ligamentum arteriosum?
Intramembranous ossification is primarily seen in which of the following bones?
Which is the earliest secondary ossification center to develop chronologically?
What anatomical structure is formed after the obliteration of the umbilical vein?
Embryology and Development Indian Medical PG Practice Questions and MCQs
Question 1121: 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 1122: 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 1123: Which is the first bone to start ossifying?
- A. Femur
- B. Clavicle (Correct Answer)
- C. Tibia
- D. Mandible
Explanation: ***Clavicle*** - The **clavicle** is the **first bone to begin ossification** in the human body, starting around the **5th-6th week of gestation**. - It ossifies via **intramembranous ossification**, making it unique among long bones [1]. - This early ossification is a key landmark in fetal skeletal development and is consistently taught across medical curricula. *Mandible* - The **mandible** begins ossification around the **6th week of gestation**, shortly after the clavicle [1]. - While it is one of the earliest bones to ossify, it is **not the first**. - It also undergoes intramembranous ossification [1]. *Femur* - The **femur**, a long bone, begins ossification around the **7th-8th week of gestation** [1]. - It ossifies via **endochondral ossification**, which typically occurs later than intramembranous ossification [1]. *Tibia* - The **tibia** also begins ossification around the **7th-8th week of gestation**. - Like the femur, it follows the endochondral ossification pathway.
Question 1124: 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 1125: 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 1126: Tail of pancreas develops from -
- A. Hepatic diverticulum
- B. Ventral pancreatic bud
- C. Dorsal pancreatic bud (Correct Answer)
- D. All of the options
Explanation: Dorsal pancreatic bud - The dorsal pancreatic bud forms the majority of the pancreas, including the body, tail, and most of the head [1]. - It arises from the dorsal mesentery of the duodenum [1]. Hepatic diverticulum - The hepatic diverticulum gives rise to the liver, gallbladder, and bile ducts [2]. - It is separate from the pancreatic development and does not contribute to the pancreas. Ventral pancreatic bud - The ventral pancreatic bud forms only a small part of the pancreas, specifically the inferior portion of the head and the uncinate process [1]. - It rotates posteriorly with the duodenum to fuse with the dorsal bud [1]. All of the options - This option is incorrect because only the dorsal pancreatic bud forms the tail of the pancreas [1]. - The hepatic diverticulum does not contribute to pancreatic development at all, and the ventral pancreatic bud only forms the uncinate process and part of the head [1].
Question 1127: 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 1128: Intramembranous ossification is primarily seen in which of the following bones?
- A. Pelvis
- B. Long bones
- C. Maxilla and mandible (Correct Answer)
- D. None of the options
Explanation: ***Maxilla and mandible*** - **Intramembranous ossification** directly forms bone from mesenchymal tissue without a cartilaginous precursor [1]. - This process is characteristic of most **flat bones of the skull**, including the maxilla and mandible [1]. - The **clavicle** also undergoes intramembranous ossification (though it uniquely combines both intramembranous and endochondral processes) [1]. *Pelvis* - The pelvis develops primarily through **endochondral ossification**, where a cartilage model is first formed and then replaced by bone [1]. - While some parts might involve intramembranous ossification to a limited extent, it is not the primary mode of formation for the pelvis as a whole. *Long bones* - **Long bones** (e.g., femur, tibia, humerus) develop almost exclusively through **endochondral ossification** [1]. - This process is essential for the longitudinal growth of bones at the **epiphyseal plates** [2]. *None of the options* - This option is incorrect because the **maxilla and mandible** are clear examples of bones that primarily undergo intramembranous ossification.
Question 1129: Which is the earliest secondary ossification center to develop chronologically?
- A. Lower end of femur (Correct Answer)
- B. Upper end of humerus
- C. Lower end of fibula
- D. Upper end of tibia
Explanation: ***Lower end of femur*** - The **distal femoral epiphysis** is typically the first secondary ossification center to appear, often present at birth or shortly before [1]. - Its presence at birth is an indicator of **fetal maturity**, making it a key developmental landmark [1]. *Upper end of humerus* - The **proximal humeral epiphysis** typically ossifies around 6 months of age, significantly later than the distal femur. - This center contributes to the growth of the humeral head and greater tubercle. *Lower end of fibula* - The **distal fibular epiphysis** appears around the first year of life, after both the distal femur and proximal humerus. - It forms part of the ankle joint and contributes to its stability. *Upper end of tibia* - The **proximal tibial epiphysis** typically ossifies around 6-12 months of age, well after the distal femur. - This center is crucial for the growth of the upper tibia and knee joint development.
Question 1130: What anatomical structure is formed after the obliteration of the umbilical vein?
- A. Ligamentum venosum
- B. Ligamentum arteriosum
- C. Medial umbilical ligament
- D. Round ligament of the liver (ligamentum teres) (Correct Answer)
Explanation: ***Round ligament of the liver (ligamentum teres)*** - The **umbilical vein** carries oxygenated blood from the placenta to the fetus during development [1]. - After birth, the umbilical vein obliterates and forms the **round ligament of the liver**, also known as the **ligamentum teres hepatis**. *Ligamentum venosum* - This structure is the obliterated remnant of the **ductus venosus**, which shunted blood from the umbilical vein to the inferior vena cava, bypassing the fetal liver [1]. - It is located in a fissure on the posterior surface of the liver, separate from the round ligament. *Ligamentum arteriosum* - This ligament is the remnant of the **ductus arteriosus**, a fetal blood vessel connecting the pulmonary artery to the aorta. - Its obliteration allows blood to flow through the lungs after birth. *Medial umbilical ligament* - This ligament is formed from the obliterated **umbilical arteries**, which carry deoxygenated blood from the fetus back to the placenta. - There are two medial umbilical ligaments, one from each umbilical artery.
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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