Development of Urogenital System — MCQs
What is the most common cause of pure gonadal dysgenesis with XY karyotype?
The Finnish type of congenital nephrotic syndrome occurs due to gene mutation affecting the following protein –
The prostate gland is derived from?
Which of the following conditions is least likely to present with ambiguous genitalia?
If a baby has a XX or XY genotype, normal internal gonads, but ambiguous external genitalia, it is called?
Sertoli cells are derived from -
Which of the following is a derivative of paramesonephric duct in males ?
Causes of retention of urine in reproductive age group: a) Cervical fibroid b) Retroverted gravid uterus c) Unilateral hydronephrosis d) Severe UTI e) Posterior urethral valve
Which of the following structures is involved in the formation of the diaphragm?
What is the incorrect statement?
Development of Urogenital System Indian Medical PG Practice Questions and MCQs
Question 1: What is the most common cause of pure gonadal dysgenesis with XY karyotype?
- A. Deletion
- B. Point mutation (Correct Answer)
- C. Insertion
- D. Translocation
Explanation: Point mutation - The most common genetic cause of **pure gonadal dysgenesis with XY karyotype** (Swyer syndrome) is a **point mutation** within the **SRY gene**, located on the Y chromosome [1]. - Point mutations include **missense mutations** (amino acid substitution) and **nonsense mutations** (premature stop codon), both of which can render the SRY protein non-functional. - This specific type of mutation leads to a non-functional SRY protein, preventing the development of testes in an individual with an XY karyotype and resulting in streak gonads [1]. *Deletion* - While deletions involving the SRY gene can cause XY gonadal dysgenesis, **complete deletion** of SRY is less common than point mutations as the primary cause of pure gonadal dysgenesis. - Larger deletions on the Y chromosome might also affect other genes, leading to a broader spectrum of phenotypes. *Insertion* - **Insertions** are a type of frameshift mutation where nucleotides are added to the DNA sequence. - While insertions in the SRY gene could theoretically cause gonadal dysgenesis, they are much less commonly reported than point mutations as the cause of Swyer syndrome. *Translocation* - **Translocations** involving the SRY gene, such as SRY being translocated to an X chromosome, can lead to sex reversal (XX male phenotype). - However, for pure XY gonadal dysgenesis (where SRY is present but non-functional), translocations are not the most common underlying genetic mechanism.
Question 2: The Finnish type of congenital nephrotic syndrome occurs due to gene mutation affecting the following protein –
- A. Nephrin (Correct Answer)
- B. Alpha–actinin
- C. Podocin
- D. CD2-associated protein
Explanation: The Finnish type of congenital nephrotic syndrome occurs due to gene mutation affecting the following protein – ***Nephrin*** * The **Finnish type congenital nephrotic syndrome (CNF)** is specifically caused by mutations in the *NPHS1* gene, which codes for the protein **nephrin**. * **Nephrin** is a crucial component of the **slit diaphragm** in podocytes, essential for maintaining the glomerular filtration barrier and preventing protein loss [1]. *Alpha–actinin* * **Alpha-actinin** is a protein that anchors actin filaments to various membrane structures, including the podocyte cytoskeleton. * Mutations in genes encoding alpha-actinin (e.g., *ACTN4*) are associated with some forms of **focal segmental glomerulosclerosis (FSGS)**, but not specifically the Finnish type CNF [1]. *CD2 activated protein* * **CD2-associated protein (CD2AP)** is another important podocyte protein involved in anchoring the slit diaphragm to the actin cytoskeleton [1]. * Mutations in the *CD2AP* gene can cause some forms of **steroid-resistant nephrotic syndrome** and FSGS, but not the Finnish type CNF. *Podocin* * **Podocin** is a lipid raft-associated protein in podocytes, encoded by the *NPHS2* gene, crucial for stabilizing nephrin and forming the slit diaphragm [1]. * Mutations in *NPHS2* (leading to podocin dysfunction) are a common cause of **steroid-resistant nephrotic syndrome** in childhood, but not the Finnish type congenital nephrotic syndrome. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 923-924.
Question 3: The prostate gland is derived from?
- A. Urogenital sinus (Correct Answer)
- B. Urogenital folds
- C. Labioscrotal swelling
- D. Gubernaculum
Explanation: ***Urogenital sinus*** - The **prostate gland** develops from endodermal buds that arise from the **urethral epithelium** of the urogenital sinus during the third month of gestation. - These buds grow into the surrounding mesenchyme, which differentiates into the stromal and smooth muscle components of the prostate. *Urogenital folds* - The **urogenital folds** (or urethral folds) in males fuse to form the **spongy urethra** and the ventral aspect of the penis. - In females, these folds remain separate and form the labia minora. *Labioscrotal swelling* - The **labioscrotal swellings** in males fuse in the midline to form the **scrotum**. - In females, these swellings remain unfused and give rise to the labia majora. *Gubernaculum* - The **gubernaculum** is a mesenchymal cord that plays a crucial role in the **descent of the testes** into the scrotum. - It guides the migrating testis and anchors it to the scrotal floor.
Question 4: Which of the following conditions is least likely to present with ambiguous genitalia?
- A. Hermaphroditism
- B. Super female (47 XXX) (Correct Answer)
- C. Gonadal dysgenesis
- D. Gonadal agenesis
Explanation: ***Super female (47 XXX)*** - Individuals with **47,XXX syndrome**, often called "triple X syndrome," typically have a **normal female phenotype** and are not usually born with ambiguous genitalia. - While they may have some developmental differences or fertility issues, their external genitalia are typically **unambiguously female**. *Gonadal dysgenesis* - This condition involves **abnormal development of the gonads**, leading to a spectrum of presentations that can include **ambiguous genitalia**. - Incomplete differentiation of the testes or ovaries can result in external genitalia that are neither definitively male nor female. *Hermaphroditism* - **True hermaphroditism** (now referred to as **ovotesticular disorder of sex development**) is characterized by the presence of **both ovarian and testicular tissue** in the same individual. - This condition almost always results in **ambiguous external genitalia** because the sex hormone production is mixed. *Gonadal agenesis* - **Gonadal agenesis** refers to the **complete absence of gonads**, which can lead to ambiguous genitalia, particularly if gonadal development failed before external genitalia differentiation. - Without the hormones produced by the gonads (e.g., androgens from testes), the development of male external genitalia is impaired, leading to **under-masculinization** or ambiguous features.
Question 5: If a baby has a XX or XY genotype, normal internal gonads, but ambiguous external genitalia, it is called?
- A. True hermaphrodite
- B. Disorder of Sex Development (DSD) (Correct Answer)
- C. Intersex (outdated term)
- D. Any of the above
- E. Pseudohermaphrodite
Explanation: ***Disorder of Sex Development (DSD)*** - This is the **current preferred medical terminology** that encompasses conditions where there is a discrepancy between chromosomal sex, gonadal sex, and anatomical sex. - The scenario described—normal XX or XY genotype and normal internal gonads with **ambiguous external genitalia**—fits the definition of a DSD. - This **umbrella term** has replaced older terminology and is the most appropriate answer in modern medical practice. *True hermaphrodite* - A true hermaphrodite, now referred to as **ovotesticular DSD**, possesses both ovarian and testicular tissue simultaneously. - The question specifies **normal internal gonads** (either ovaries or testes, not both), which excludes this diagnosis. *Intersex (outdated term)* - While "intersex" was historically used to describe individuals with atypical sexual characteristics, it is now considered an **outdated and less precise** term in medical contexts. - "Disorder of Sex Development" is the preferred and more comprehensive medical classification. *Pseudohermaphrodite* - This was the **classical medical term** for exactly this presentation: normal chromosomal sex and appropriate internal gonads but ambiguous external genitalia. - Examples include 46,XX DSD with virilization (e.g., **congenital adrenal hyperplasia**) or 46,XY DSD with undervirilization (e.g., **androgen insensitivity syndrome**). - This term has been **replaced by DSD terminology** in modern medical practice to avoid stigmatizing language. *Any of the above* - While multiple terms have been used historically, **DSD is the most accurate and currently accepted medical term** for this specific presentation. - Therefore, this option is incorrect as it suggests all answers are equally valid.
Question 6: Sertoli cells are derived from -
- A. Genital swelling
- B. Coelomic epithelium (Correct Answer)
- C. Primordial germ cells
- D. Germinal epithelium
Explanation: Sertoli cells are derived from the **coelomic epithelium** (surface epithelium) of the urogenital ridge during gonadal development. - The coelomic epithelium proliferates to form the **primitive sex cords** (medullary cords in males), and cells within these cords differentiate into Sertoli cells. - These cells are essential for **spermatogenesis**, providing structural support and nutrition to developing germ cells, and producing **anti-Müllerian hormone (AMH)** which causes regression of Müllerian ducts in male development [1]. *Germinal epithelium* - This is an **outdated term** previously used for the surface epithelium of the gonad, based on the misconception that it gave rise to germ cells. - Modern embryology uses the term **coelomic epithelium** or surface epithelium instead. - While historically used, this terminology is no longer preferred in current medical literature. *Genital swelling* - **Genital swellings** (labioscrotal swellings) are external mesodermal structures that develop into the **scrotum** in males or **labia majora** in females. - These are external genitalia components and are not the source of internal testicular cells like Sertoli cells. *Primordial germ cells* - **Primordial germ cells (PGCs)** originate from the epiblast, migrate via the hindgut to the developing gonads, and differentiate into **spermatogonia** (males) or **oogonia** (females) [1]. - They form the **germ cell lineage** (gametes), not somatic support cells like Sertoli cells, which are of coelomic epithelial origin.
Question 7: 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 8: Causes of retention of urine in reproductive age group: a) Cervical fibroid b) Retroverted gravid uterus c) Unilateral hydronephrosis d) Severe UTI e) Posterior urethral valve
- A. ACD
- B. BCD
- C. ABC
- D. ABD (Correct Answer)
Explanation: ***Correct: ABD*** - **Cervical fibroid** and **retroverted gravid uterus** can cause extrinsic compression of the urethra or bladder neck, leading to **urinary retention** in women of reproductive age. - **Severe UTI** can cause bladder inflammation and dysfunction, manifesting as acute urinary retention. *Incorrect: ACD* - This option incorrectly includes **unilateral hydronephrosis** as a direct cause of urinary retention. - Unilateral hydronephrosis is typically due to an obstruction higher up in one ureter and does not directly obstruct bladder emptying, though bilateral hydronephrosis *could* occur with lower urinary tract obstruction. *Incorrect: BCD* - This option correctly identifies **retroverted gravid uterus** and **severe UTI** as causes but incorrectly includes **unilateral hydronephrosis**. - It also omits **cervical fibroid**, which is a significant cause of retention in this demographic. *Incorrect: ABC* - This option incorrectly includes **unilateral hydronephrosis**. - Unilateral hydronephrosis affects the upper urinary tract (kidney/ureter) and does not cause bladder outlet obstruction or urinary retention. **Key Points:** - **Cervical fibroid**: Causes mechanical urethral/bladder neck compression - **Retroverted gravid uterus**: Classic cause in 2nd trimester (12-16 weeks) when incarcerated uterus compresses urethra - **Severe UTI**: Causes retention via bladder inflammation, edema, and detrusor dysfunction - **Unilateral hydronephrosis**: Upper urinary tract issue, NOT a cause of urinary retention - **Posterior urethral valve**: Congenital male condition, irrelevant to reproductive age women
Question 9: Which of the following structures is involved in the formation of the diaphragm?
- A. Mesonephros
- B. Neural crest cells
- C. Urogenital ridge
- D. Septum transversum (Correct Answer)
Explanation: ***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 10: What is the incorrect statement?
- A. MIS inhibits the formation of Mullerian duct
- B. WD form male internal genitalia
- C. Zygote is Bipotential at 8 weeks (Correct Answer)
- D. DHT is necessary for the development of external genitals
Explanation: ***Zygote is Bipotential at 8 weeks*** - A **zygote** is formed at conception and is the single-cell diploid organism, not bipotential at 8 weeks. - The **bipotential gonad** can develop into either testes or ovaries, and this stage of sexual differentiation occurs earlier in gestation, typically around the 6th to 7th week, before differentiating into male or female gonads, not at 8 weeks as an entire zygote. *MIS inhibits the formation of Mullerian duct* - **Müllerian Inhibiting Substance (MIS)**, also known as **Anti-Müllerian Hormone (AMH)**, is produced by the Sertoli cells of the developing testes [1]. - Its primary function is to cause the **regression of the Müllerian ducts**, which would otherwise develop into female internal reproductive structures (fallopian tubes, uterus, and upper vagina) [1]. *WD form male internal genitalia* - The **Wolffian ducts (WD)**, also known as mesonephric ducts, are precursors to male internal genitalia in the presence of testosterone [1]. - stimulated by **testosterone** produced by the Leydig cells of the fetal testes, they develop into the **epididymis, vas deferens, and seminal vesicles** [1]. *DHT is necessary for the development of external genitals* - **Dihydrotestosterone (DHT)**, a more potent form of testosterone, is crucial for the development of male external genitalia [1]. - The enzyme **5α-reductase** converts testosterone to DHT in target tissues, leading to the formation of the **penis, scrotum, and prostate** [1].
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