Embryology and Development Practice Questions

Q: Anatomical closure of ductus arteriosus occurs at –

30th day. ***30th day (2-3 weeks)*** - The **ductus arteriosus (DA)** undergoes **anatomical closure** between **2-3 weeks** (approximately 14-21 days) after birth, transforming into the **ligamentum arteriosum** [2]. - This process involves **fibrosis and permanent structural changes** that complete by approximately 3-4 weeks of age [2]. - Anatomical closure follows the earlier **functional closure**, which occurs within the first 12-24 hours (up to 72 hours) of life [2]. *10th day* - At 10 days, the ductus arteriosus is typically in the **process of anatomical closure** but has not yet completed the full fibrotic transformation. - Complete anatomical obliteration generally requires **2-3 weeks**, making 10 days too early for complete anatomical closure [2]. *3-4 day* - At 3-4 days, **functional closure** has typically occurred, but **anatomical closure** has barely begun. - The vessel may still be patent on imaging, and the structural remodeling into ligamentum arteriosum is in its early stages. *Birth* - At **birth**, the ductus arteriosus is **open and functional**, allowing blood to bypass the fetal lungs [1]. - Closure begins shortly after birth due to increased oxygen tension and decreased prostaglandin levels, but the DA is patent at birth [1], [2].

Q: Space of Cloquet is phylogenetically related to

Hyaloid artery. ***Hyaloid artery*** - The **Space of Cloquet** (also known as the hyaloid canal or retrolental space of Cloquet) is the embryonic remnant of the **hyaloid artery**. - During fetal development, the hyaloid artery nourishes the developing lens and vitreous, and usually regresses completely before birth, leaving behind the empty canal. *Iris* - The iris is the colored part of the eye responsible for controlling pupil size and light entry, and its development is distinct from the hyaloid artery system. - While it plays a crucial role in the mature eye, it does not share a direct phylogenetic or developmental connection with Cloquet's space. *Central Retinal artery* - The central retinal artery supplies blood to the inner layers of the retina and is a branch of the ophthalmic artery. - It develops separately and has a different function than the hyaloid artery system, which is primarily involved in early ocular development. *Central retinal vein* - The central retinal vein drains blood from the retina and is also a distinct vascular structure separate from the hyaloid artery. - Its development and function are related to retinal blood outflow, not the regression of fetal vitreous structures.

Q: Branchial cyst arises from which branchial cleft:

Second. ***Second*** - **Branchial cysts** most commonly arise from the **incomplete obliteration of the second branchial cleft** (90-95% of all branchial cysts). - They typically present as a **smooth, mobile, non-tender mass** in the lateral neck, anterior to the sternocleidomastoid muscle [1]. - Most common presentation: a painless swelling in the **upper third of the neck** along the anterior border of SCM [1]. *Third* - Cysts arising from the **third branchial cleft** are very rare and typically present lower in the neck, often extending towards the **pyriform sinus**. - These are less common than second branchial cleft cysts and may be associated with **thyroid or parathyroid abnormalities**. *First* - Anomalies of the **first branchial cleft** are rare and typically manifest as cysts or sinuses close to the **external auditory canal** or angle of the mandible. - They are often associated with the **parotid gland** and facial nerve. *Fourth* - **Fourth branchial cleft anomalies** are also very rare and usually present as a sinus or fistula in the lower neck, often entering the **pyriform sinus** and associated with recurrent infections. - They have a distinct tract that can connect to the pharynx.

Q: The following ocular structure is not derived from surface ectoderm –

Sclera. **Sclera** - The **sclera** develops from the **neural crest cells**, which differentiate into mesenchymal tissue around the optic cup, forming the fibrous coats of the eye [1]. - It is part of the **fibrous tunic** of the eye, along with the cornea, and provides structural support. *Epithelium of lacrimal glands* - The **epithelium of lacrimal glands** originates from the **surface ectoderm** through invaginations and subsequent differentiation. - These glands are responsible for producing the **watery component of tears**. *Crystalline lens* - The **crystalline lens** also develops from the **surface ectoderm**, specifically from the lens placode, which invaginates to form the lens vesicle. - It is crucial for **focusing light** onto the retina. *Corneal epithelium* - The **corneal epithelium** is derived from the **surface ectoderm** and forms the outermost layer of the cornea [1]. - It provides a **protective barrier** and helps maintain the smooth refractive surface of the cornea [1].

Q: Acrosome cap of the sperm derived from ?

Golgi body. Golgi body - During spermiogenesis, the Golgi apparatus in the spermatid migrates to the anterior pole of the cell and condenses to form the acrosomal vesicle [1]. - This vesicle then spreads over the anterior half of the nucleus to become the acrosome cap, which contains hydrolytic enzymes crucial for fertilization [1]. Nucleus - The nucleus contains the genetic material (DNA) of the sperm, but it does not directly form the acrosome cap [1]. - The nucleus is located posterior to the acrosome, and its primary function is to transmit paternal chromosomes. Mitochondria - Mitochondria are concentrated in the midpiece of the sperm, providing ATP for flagellar movement [1]. - They are essential for sperm motility but play no role in the formation of the acrosome cap. Centriole - The proximal and distal centrioles are located at the base of the nucleus and are involved in forming the axoneme (the core of the flagellum). - Centrioles are critical for sperm tail development and function, but not for acrosome formation.

Q: All of the following develops from surface ectoderm except

Epithelial lining of iris. Epithelial lining of iris (Correct Answer) - The epithelial lining of the iris develops from the neuroectoderm (specifically, the anterior extension of the optic cup), not the surface ectoderm. - This neuroectodermal origin differentiates it from other ocular structures that do arise from surface ectoderm. - Both layers of the iris epithelium (anterior and posterior pigmented layers) are derived from the two layers of the optic cup. [1] Lens (Incorrect) - The lens is a classic derivative of the surface ectoderm, forming as the lens placode invaginates after induction by the optic vesicle. - Its development is crucial for vision and is a key example of surface ectoderm differentiation in the head region. Lacrimal gland (Incorrect) - The lacrimal gland, responsible for tear production, develops from the surface ectoderm of the conjunctival sac. - It forms through a series of epithelial buds that invaginate into the surrounding mesenchyme. Epithelial lining of conjunctiva (Incorrect) - The epithelial lining of the conjunctiva, which covers the sclera and lines the eyelids, is derived from the surface ectoderm. [2] - This layer provides protection and lubrication to the eye.

Q: Nasolabial cyst occurs at-

Union of nasal and maxillary process. ***Union of nasal and maxillary process*** - A nasolabial cyst (also known as a nasoalveolar cyst or Klestadt's cyst) is a **non-odontogenic cyst** believed to arise from remnants of the **nasolacrimal duct** at the junction of embryonic facial processes. - This specific location corresponds to the fusion of the **lateral nasal process** and the **maxillary process**, leading to a cyst in the soft tissue of the upper lip lateral to the ala of the nose. *Union of palatal process with maxillary* - Cysts arising from the fusion of the palatal process with the maxillary process typically result in **globulomaxillary cysts**, which are located between the maxillary lateral incisor and canine. - This embryological origin differs significantly from the location of a nasolabial cyst. *Nasal with palatal process* - This union is not a recognized embryonic facial fusion point that correlates with the formation of a specific cyst type like the nasolabial cyst. - Cysts related to the palate generally involve palatal processes or median palatal structures. *Union of two nasal processes* - The fusion of the medial nasal processes forms the **primary palate** and the premaxilla; cysts in this central region are often **median palatal cysts** or **nasopalatine duct cysts**. - This location is distinct from the lateral soft tissue location of a nasolabial cyst.

Q: Gland homologous to prostate in females is

Skene's gland. ***Skene's gland*** - **Skene's glands**, also known as the **paraurethral glands**, are located on either side of the female urethra [1]. - They are considered homologous to the male prostate gland as they share similar embryological origins and secrete a fluid that is believed to play a role in sexual function [1]. *Bartholin's gland* - **Bartholin's glands** are located at the posterior aspect of the vaginal opening and secrete mucus to lubricate the vagina. - These glands are homologous to the **bulbourethral glands (Cowper's glands)** in males, not the prostate [1]. *Gartner's duct* - **Gartner's duct** is a vestigial remnant of the **Wolffian (mesonephric) duct** in females. - It is not a functional gland and has no homology to the prostate gland. - Gartner's duct cysts may occasionally be found along the anterolateral wall of the vagina. *Cowper's gland* - **Cowper's glands**, or **bulbourethral glands**, are male accessory glands located below the prostate. - Their female homologue is the **Bartholin's gland**, not the prostate [1].

Q: Cantrell pentalogy include all except

Trisomy 21. ***Trisomy 21*** - **Cantrell's pentalogy** is a rare congenital condition involving defects of the **diaphragm**, **abdominal wall**, **pericardium**, **sternum**, and **heart**. - **Trisomy 21 (Down syndrome)** is a chromosomal abnormality characterized by distinct facial features, intellectual disability, and various congenital anomalies, but it is not a component of Cantrell's pentalogy. *ASD* - An **atrial septal defect (ASD)** is a common cardiac anomaly found in Cantrell's pentalogy, resulting from improper development of the heart. - The cardiac defect is one of the five primary components of **Cantrell's pentalogy**. *VSD* - A **ventricular septal defect (VSD)** is another frequent cardiac defect associated with Cantrell's pentalogy. - This defect involves a hole in the wall separating the two lower chambers of the heart and is a key feature of the **cardiac malformation component**. *TOF* - **Tetralogy of Fallot (TOF)** is a complex congenital heart defect often seen in cases of Cantrell's pentalogy. - It comprises four specific heart anomalies and contributes to the significant **cardiovascular malformations** in this syndrome.

Q: The hydatid of Morgagni is a cystic remnant of

Fallopian tube. ***Fallopian tube*** - The **hydatid of Morgagni** (also called **appendix vesiculosa**) is a small cystic structure found on the **fimbriated end of the fallopian tube** in females [1]. - It represents an embryonic remnant of the **paramesonephric (Müllerian) duct** [1]. - These cysts are typically **asymptomatic** unless they undergo **torsion**, which can cause acute pelvic pain. - The term "hydatid of Morgagni" can also refer to the **appendix testis** in males, which is also a Müllerian duct remnant. *Cervix* - The cervix is the lower part of the uterus and develops from the **paramesonephric duct**, but the hydatid of Morgagni specifically refers to the fimbrial cyst, not cervical structures. - **Nabothian cysts** can occur in the cervix but are **retention cysts** from blocked cervical glands, not embryonic remnants. *Ovary* - Ovaries develop from the **gonadal ridge** and can have various cysts (**follicular, corpus luteum**), but these are functional or neoplastic, not embryonic duct remnants [2]. - The hydatid of Morgagni is specifically an **adnexal structure** associated with the fallopian tube, not the ovary itself. *Uterus* - The uterine body develops from fusion of the **paramesonephric ducts**, but the hydatid of Morgagni is specifically located at the **fimbriated end of the fallopian tube** [3]. - Uterine pathologies include **leiomyomas** and **endometrial polyps**, which are unrelated to the hydatid of Morgagni.

Question 1

Anatomical closure of ductus arteriosus occurs at –

Accepted Answer

30th day

Answer

3–4 day

Answer

Birth

Answer

10th day

Question 2

Space of Cloquet is phylogenetically related to

Accepted Answer

Hyaloid artery

Answer

Iris

Answer

Central Retinal artery

Answer

Central retinal vein

Question 3

Branchial cyst arises from which branchial cleft:

Accepted Answer

Second

Answer

Third

Answer

First

Answer

Fourth

Question 4

The following ocular structure is not derived from surface ectoderm –

Accepted Answer

Sclera

Answer

Epithelium of lacrimal glands

Answer

Crystalline lens

Answer

Corneal epithelium

Question 5

Acrosome cap of the sperm derived from ?

Accepted Answer

Golgi body

Answer

Nucleus

Answer

Mitochondria

Answer

Centriole

Question 6

All of the following develops from surface ectoderm except

Accepted Answer

Epithelial lining of iris

Answer

Lens

Answer

Lacrimal gland

Answer

Epithelial lining of conjunctiva

Question 7

Nasolabial cyst occurs at-

Accepted Answer

Union of nasal and maxillary process

Answer

Union of palatal process with maxillary

Answer

Union of nasal with palatal process

Answer

Union of two nasal processes

Question 8

Gland homologous to prostate in females is

Accepted Answer

Skene's gland

Answer

Bartholin's gland

Answer

Gartner's duct

Answer

Cowper's gland

Question 9

Cantrell pentalogy include all except

Accepted Answer

Trisomy 21

Answer

ASD

Answer

VSD

Answer

TOF

Question 10

The hydatid of Morgagni is a cystic remnant of

Accepted Answer

Fallopian tube

Answer

Cervix

Answer

Ovary

Answer

Uterus

Embryology and Development — MCQs

Embryology and Development — MCQs

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