Embryology and Development Practice Questions

Q: SRY gene is located on -

Short arm of Y chromosome. ***Short arm of Y chromosome*** - The **SRY gene** (Sex-determining Region Y gene) is located on the **short arm of the Y chromosome** at position Yp11.3. - This gene is crucial for initiating **male sexual development** by triggering the differentiation of the gonads into testes. *Long arm of X chromosome* - The **X chromosome** is generally much larger than the Y chromosome and carries many genes crucial for both sexes. - Genes on the **long arm of the X chromosome** are involved in various functions but not primary sex determination in males. *Short arm of X chromosome* - The **short arm of the X chromosome** contains genes fundamental for development, like SHOX, but not the SRY gene. - The SRY gene's presence on the Y chromosome is what defines biological male sex. *Long arm of Y chromosome* - The **long arm of the Y chromosome** (Yq) contains genes involved in **spermatogenesis** and other male-specific functions. - However, the SRY gene, which is responsible for the initial male sex determination, is not located on the long arm.

Q: Branchial cyst develops from-

2nd branchial cleft. 2nd branchial cleft - Branchial cysts, also known as **cervical sinus cysts**, are congenital epithelial cysts that arise from incomplete obliteration of the **pharyngeal (branchial) apparatus** during embryonic development. - The most common type, composing over 90% of cases, originates from the **second branchial cleft**. *Branchial arch* - Branchial arches are mesenchymal structures that give rise to various **head and neck structures** including muscles, bones, nerves, and vessels. - While related to overall head and neck development, cysts specifically develop from unclosed clefts or pouches, not the arches themselves. *4th branchial cleft* - Cysts from the **fourth branchial cleft** are very rare, accounting for less than 1% of all branchial anomalies. - These typically present with a more inferior neck mass and can be associated with **pyriform sinus fistulas**. *3rd branchial cleft* - Cysts from the **third branchial cleft** are uncommon and often present as a mass in the upper part of the neck, deep to the sternocleidomastoid muscle. - They are less frequent than second cleft cysts but more common than fourth cleft anomalies.

Q: Remnants of Wolffian ducts in a female are found in

Broad ligament. ***Broad ligament*** - In females, remnants of the **Wolffian (mesonephric) ducts** can persist as structures such as the **epoophoron**, **paroophoron**, and **Gartner's duct cysts**, which are typically found within the broad ligament [1]. - The **broad ligament** is a fold of peritoneum that extends from the lateral walls of the uterus to the sidewalls of the pelvis, enclosing these developmental remnants. *Uterovesical pouch* - This is a peritoneal reflection between the **uterus and the bladder** and does not typically contain remnants of the Wolffian ducts. - It is a common site for fluid accumulation but not for developmental anomalies related to the mesonephric system. *Pouch of Douglas* - Also known as the **recto-uterine pouch**, this is the most dependent part of the peritoneal cavity in females, located between the **uterus and the rectum**. - While it can accumulate fluid or pathology, it is not where Wolffian duct remnants are primarily located. *Iliac fossa* - The **iliac fossa** contains structures like the **iliacus muscle**, **lymph nodes**, and parts of the bowel, but it is not the anatomical location for the remnants of the Wolffian ducts in females. - This region is more involved in supporting abdominal contents and housing major blood vessels and nerves rather than reproductive developmental remnants.

Q: Nasopharyngeal chordoma arises from:-

Notochord. Correct Option: Notochord - **Chordomas** are rare malignant tumors that arise from embryonic remnants of the **notochord** [1] - The notochord is a flexible rod-like structure that forms the primitive axial skeleton during embryonic development - Chordomas typically occur along the **midline** at sites where notochordal remnants persist, most commonly at the **skull base (clivus/nasopharynx)** and **sacrococcygeal region** [1] Incorrect Option: Luschka's bursa - **Luschka's bursa** (also known as the pharyngeal bursa) is a small indentation or pocket in the nasopharynx posterior to the pharyngeal tonsil - While located in the nasopharynx, it is a **normal anatomical structure**, not an embryological remnant that gives rise to tumors - Not associated with chordoma development Incorrect Option: Pharyngeal bursa - **Pharyngeal bursa** is another term for **Luschka's bursa** (they are synonymous) - It is a normal anatomical structure in the nasopharynx - Not related to the embryonic remnants that give rise to chordomas Incorrect Option: Rathke's pouch - **Rathke's pouch** is an embryonic invagination of the stomodeum (primitive oral cavity) that gives rise to the **anterior pituitary gland** - Tumors arising from remnants of Rathke's pouch are **craniopharyngiomas**, which are distinct from chordomas - Craniopharyngiomas are typically suprasellar, while chordomas are more commonly found at the clivus or sacrum

Q: In a 3 month fetus, characteristic feature seen is:

Nails are visible. ***Nails are visible*** - By the end of the **third month** (approximately 12 weeks), the fingers and toes are fully formed, and the beginnings of fingernails and toenails usually become visible. - This marks a significant developmental milestone in fetal maturation during the first trimester. *Meconium is present in the intestines* - **Meconium** begins to form during the **second trimester**, typically around weeks 12-16, with significant accumulation in the latter part of the second and throughout the third trimester. - While some gut movements occur earlier, the presence of well-formed meconium for defecation happens later in fetal development. *Anus formation begins* - The formation of the anus is part of the development of the **cloaca**, which begins much earlier, around the **4th to 7th gestational weeks**. - By 3 months, the anorectal canal is already well-differentiated, so its formation has already been completed. *Limb buds are present* - **Limb buds** appear very early in embryonic development, around the **end of the 4th week**. [1] - By 3 months, the limbs are already well-developed with distinct fingers and toes, so these structures would have passed the "bud" stage.

Q: Which muscle originates from 1st pharyngeal arch?

Masseter. ***Masseter*** - The **masseter muscle** is a strong muscle of mastication that originates from the **first pharyngeal arch**. - Muscles derived from the first pharyngeal arch are innervated by the **trigeminal nerve (CN V)**, which also innervates the masseter. *Posterior belly of digastric* - The **posterior belly of the digastric muscle** originates from the **second pharyngeal arch**. - It is innervated by the **facial nerve (CN VII)**, which is associated with the second pharyngeal arch. *Buccinator* - The **buccinator muscle** is a muscle of facial expression that also originates from the **second pharyngeal arch**. - Like other muscles of facial expression, it is innervated by the **facial nerve (CN VII)**. *Stylopharyngeus* - The **stylopharyngeus muscle** originates from the **third pharyngeal arch**. - It is innervated by the **glossopharyngeal nerve (CN IX)**, which is associated with the third pharyngeal arch.

Q: Nerves of pharyngeal arch develop from

Neural crest cells. ***Neural crest cells*** - **Neural crest cells** are a multipotent, migratory population of cells that arise from the dorsal part of the neural tube and contribute to a wide array of tissues, including the nerves of the pharyngeal arches (clefts). [1] - They give rise to components of the peripheral nervous system, including **sensory ganglia**, autonomic ganglia, and some cranial nerves associated with the pharyngeal arches. [2] *Mesoderm* - **Mesoderm** is one of the three primary germ layers that forms during early embryonic development. - It primarily gives rise to muscle, bone, connective tissue, and the circulatory system, but not the nerves of the pharyngeal structures. *Neuroectoderm* - **Neuroectoderm** refers to the part of the ectoderm that gives rise to the nervous system, but specifically it differentiates into the neural tube and neural crest. - While neural crest cells originate from neuroectoderm, the direct derivative for the pharyngeal nerves are the **neural crest cells** themselves after migration. *Ectoderm* - The **ectoderm** is the outermost of the three germ layers and gives rise to the epidermis, hair, nails, and the nervous system. - While the nervous system originates from ectoderm, the specific cell type for pharyngeal arch nerves is the **neural crest**, which is a specialized derivative of the ectoderm.

Q: Superior vena cava is derived from:

Cardinal vein. ***Cardinal vein*** - The **superior vena cava (SVC)** develops primarily from the **right anterior cardinal vein** and the common cardinal veins. [1] - The cardinal veins are the main venous drainage system in the early embryo, eventually forming the major veins of the adult. *Aortic arch* - The **aortic arches** are embryonic structures that contribute to the formation of the **major arteries**, such as the aorta, carotid arteries, and subclavian arteries. - They are involved in the arterial system, not the venous drainage of the superior vena cava. *Pharyngeal arch* - **Pharyngeal arches** are embryonic structures that give rise to various components of the **head and neck**, including skeletal structures, muscles, and nerves. - They are not directly involved in the formation of major blood vessels like the superior vena cava. *Vitelline vein* - The **vitelline veins** are embryonic vessels that drain blood from the **yolk sac** and contribute to the formation of the **portal system**, including the hepatic portal vein and sinusoids. - They are not involved in the development of the systemic veins like the superior vena cava, which drains the upper body.

Q: Which of the following structures is involved in the formation of the diaphragm?

Septum transversum. ***Septum transversum*** - The **septum transversum** is a thick mass of mesenchyme that forms early in embryonic development, originating from the **cervical somites**. - It is the **most important component** in diaphragm formation, forming the **central tendon** of the diaphragm [1]. - The diaphragm develops from **four embryological sources**: septum transversum (central tendon), pleuroperitoneal membranes, dorsal mesentery of esophagus (crura), and muscular ingrowth from the body wall. - The septum transversum also contributes to the formation of the **ventral mesentery of the stomach** and the **falciform ligament** [1]. *Mesonephros* - The **mesonephros** is an embryonic kidney that functions briefly during early development. - It contributes to the formation of some parts of the **male genital system**, but not the diaphragm. *Neural crest cells* - **Neural crest cells** are multipotent cells that migrate to various regions of the embryo to form diverse tissues. - They differentiate into structures like **peripheral nervous system components**, melanocytes, and craniofacial bones, but are not directly involved in diaphragm formation. *Urogenital ridge* - The **urogenital ridge** is an embryonic structure that gives rise to the kidneys and gonads. - It is crucial for the development of the **urinary and reproductive systems**, not the diaphragm.

Question 1

In development of male fetus following statements are true except

Accepted Answer

During intrauterine life, testes do not produce hormones essential for male development.

Answer

Around 8 weeks internal and external genitalia differentiates into male pattern

Answer

Gene on short arm of Y chromosome directs testes development

Answer

Antimullerian hormone inhibits development of mullerian system in male fetus

Question 2

SRY gene is located on -

Accepted Answer

Short arm of Y chromosome

Answer

Long arm of X chromosome

Answer

Short arm of X chromosome

Answer

Long arm of Y chromosome

Question 3

Branchial cyst develops from-

Accepted Answer

2nd branchial cleft

Answer

Branchial arch

Answer

4th branchial cleft

Answer

3rd branchial cleft

Question 4

Remnants of Wolffian ducts in a female are found in

Accepted Answer

Broad ligament

Answer

Uterovesical pouch

Answer

Pouch of Douglas

Answer

Iliac fossa

Question 5

Nasopharyngeal chordoma arises from:-

Accepted Answer

Notochord

Answer

Luschka's bursa

Answer

Pharyngeal bursa

Answer

Rathke's pouch

Question 6

In a 3 month fetus, characteristic feature seen is:

Accepted Answer

Nails are visible

Answer

Meconium is present in the intestines.

Answer

Anus formation begins.

Answer

Limb buds are present.

Question 7

Which muscle originates from 1st pharyngeal arch?

Accepted Answer

Masseter

Answer

Posterior belly of digastric

Answer

Buccinator

Answer

Stylopharyngeus

Question 8

Nerves of pharyngeal arch develop from

Accepted Answer

Neural crest cells

Answer

Mesoderm

Answer

Neuroectoderm

Answer

Ectoderm

Question 9

Superior vena cava is derived from:

Accepted Answer

Cardinal vein

Answer

Aortic arch

Answer

Pharyngeal arch

Answer

Vitelline vein

Question 10

Which of the following structures is involved in the formation of the diaphragm?

Accepted Answer

Septum transversum

Answer

Mesonephros

Answer

Neural crest cells

Answer

Urogenital ridge

Embryology and Development — MCQs

Embryology and Development — MCQs

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