Comparative Reproductive System — MCQs
What is the most common site of ectopic testis?
Spermatogenesis occurs at which temperature condition?
A 23-year-old woman accompanied by her mother-in-law comes to the infertility clinic. She has been having regular intercourse for 6 months but is not able to conceive. What is the next best step?
Which of the following conditions is least likely to present with ambiguous genitalia?
Which structure can be palpated through the anterior wall of the rectum, directly in front of the rectum in the midline, during a rectal examination of a 27-year-old woman?
The morula stage consists of how many cells?
Arrange the cells according to their positions from the basal layer towards the lumen in the seminiferous tubules:- 1. Spermatogonia 2. Primary spermatocyte 3. Spermatid 4. Spermatozoa
What is the incorrect statement?
Which of the following organisms show parthenogenesis?
Which one of the following tests should be applied to compare mean haemoglobin level of two groups of antenatal mothers?
Comparative Reproductive System Indian Medical PG Practice Questions and MCQs
Question 1: What is the most common site of ectopic testis?
- A. Lumbar
- B. Root of penis
- C. Superficial inguinal pouch
- D. Superficial perineal pouch (Correct Answer)
Explanation: Detailed scientific knowledge identifies the most common sites for ectopic testis. ***Superficial perineal pouch*** - The **superficial perineal pouch** is the most common site for an **ectopic testis**, where the testis has deviated from its normal pathway of descent [1]. - This occurs when the **gubernaculum** attaches to an abnormal location, guiding the testis away from the scrotum. *Lumbar* - A lumbar location is indicative of an **intra-abdominal testis** (cryptorchidism), where the testis has not descended at all. - While possible, it is not considered an ectopic site but rather an **undescended testis** [1]. *Superficial inguinal pouch* - The **superficial inguinal pouch** is a common location for a **retractile testis** or an undescended testis that has arrested in its descent. - An ectopic testis has deviated from its normal path, which is distinct from a testis that has simply stopped descending [1]. *Root of penis* - While an ectopic testis can theoretically be found at the **root of the penis**, it is a far less common site compared to the superficial perineal pouch. - The gubernaculum would need to attach aberrantly to direct the testis to this specific location.
Question 2: Spermatogenesis occurs at which temperature condition?
- A. Temperature does not play a role
- B. Temperature lower than core body temperature (Correct Answer)
- C. Temperature higher than core body temperature
- D. Body temperature
Explanation: ***Temperature lower than core body temperature*** - Spermatogenesis, the process of sperm production, is **temperature-sensitive** and requires a cooler environment than the core body temperature. - The **scrotum** is located outside the abdominal cavity, providing a temperature that is typically 2-3°C lower than the core body temperature, which is optimal for sperm development. *Temperature does not play a role* - This statement is incorrect as temperature plays a crucial role in spermatogenesis; **elevated temperatures can impair sperm production** and function. - Testicular function, including germ cell development, is highly sensitive to heat stress. *Temperature higher than core body temperature* - A temperature higher than core body temperature would be **detrimental to spermatogenesis**, leading to reduced sperm viability and quantity. - Exposure to high temperatures, such as through cryptorchidism (undescended testes), can cause **infertility**. *Body temperature* - If spermatogenesis were to occur at core body temperature, the quality and quantity of sperm would be **significantly reduced**, potentially leading to infertility. - The evolutionary advantage of the testes being located in the scrotum is precisely to maintain this **optimal cooler temperature**.
Question 3: A 23-year-old woman accompanied by her mother-in-law comes to the infertility clinic. She has been having regular intercourse for 6 months but is not able to conceive. What is the next best step?
- A. Hysterolaparoscopy
- B. Diagnostic hysteroscopy
- C. Reassure and review the couple after 6 months (Correct Answer)
- D. Semen analysis for husband
Explanation: ***Reassure and review the couple after 6 months*** - Infertility is defined as the inability to conceive after **12 months** of regular, unprotected intercourse in women under 35 years old. For women aged 35 or older, this period is 6 months. - Since the patient is 23 years old and has been trying for only 6 months, she does not yet meet the diagnostic criteria for infertility. The appropriate action is to advise them to continue trying and to return for evaluation if conception does not occur after a full year. *Semen analysis for husband* - While a semen analysis is a crucial initial step in an infertility workup, it is premature at this stage given the duration of attempted conception. - It would be appropriate to order this test after the couple has met the criteria for infertility (12 months for women under 35). *Hysterolaparoscopy* - This is an invasive procedure typically reserved for more advanced stages of an infertility workup, especially when suspected pathologies like endometriosis or tubal factor infertility are present. - It is not indicated as an initial step for a couple who has only been trying to conceive for 6 months and does not yet meet the definition of infertility. *Diagnostic hysteroscopy* - A diagnostic hysteroscopy is used to visualize the inside of the uterus to identify intrauterine pathologies that could contribute to infertility. - Like hysterolaparoscopy, it is an invasive diagnostic tool and should only be considered after initial, less invasive investigations have been performed and the couple meets the criteria for infertility.
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: Which structure can be palpated through the anterior wall of the rectum, directly in front of the rectum in the midline, during a rectal examination of a 27-year-old woman?
- A. Bladder
- B. Body of uterus
- C. Cervix of uterus (Correct Answer)
- D. Pubic symphysis
Explanation: Cervix of uterus - The cervix is located posterior to the bladder and inferior to the body of the uterus, making it palpable through the anterior rectal wall via the rectovaginal septum [2]. - Its firm, rounded structure can be felt as a distinct nodule directly anterior to the rectum in the midline during a digital rectal examination. - This is a standard clinical finding in pelvic examination. Bladder - The bladder is anterior to the uterus and cervix; an empty bladder is usually not palpable through the anterior rectal wall. - A distended bladder would be palpable, but it would be a soft, fluctuating mass, not a firm structure like the cervix. Body of uterus - The body of the uterus is superior to the cervix and in the typical anteverted position (normal in ~80% of women), it is angled anteriorly and superiorly, generally beyond the reach of a digital rectal exam for direct palpation through the anterior rectal wall [1]. - In the less common retroverted uterus, the body may be palpable through the posterior fornix of the vagina or through the rectum, but this is not the typical anatomical relationship. Pubic symphysis - The pubic symphysis is a bony joint located at the very anterior aspect of the pelvis, far too anterior and superior to be palpable through the anterior wall of the rectum. - It forms the anterior boundary of the bony pelvis, while the rectum is situated posteriorly within the pelvic cavity.
Question 6: The morula stage consists of how many cells?
- A. 4 to 8 cell stage
- B. 28 to 32 cell stage (Correct Answer)
- C. 12 to 16 cell stage
- D. 50 to 60 cell stage
Explanation: 28 to 32 cell stage - The morula is a solid ball of cells formed through **compaction** around **day 3-4 after fertilization**, typically consisting of **16-32 blastomeres** (most commonly 28-32 cells) [1]. - This stage represents a **compacted mass** where individual cell boundaries become less distinct, forming a solid cluster before blastocyst formation [1]. - The term "morula" (Latin for "mulberry") reflects its characteristic appearance at this cell count [1]. *12 to 16 cell stage* - This represents the **early/transitional morula stage** where compaction is just beginning [1]. - While sometimes included in broader definitions, the **classic morula** is defined at higher cell counts (16-32 cells) [1]. - Most embryology textbooks specify morula formation at 16+ cells [1]. *4 to 8 cell stage* - This is an **early cleavage stage** occurring around **day 2-3 after fertilization** [1]. - Cells (blastomeres) are still distinct and **loosely arranged**, without the compaction characteristic of morula. - This precedes morula formation by approximately 1 day. *50 to 60 cell stage* - At this cell count, the embryo has progressed to the **blastocyst stage** (around day 5) [1]. - The blastocyst features **cell differentiation** into inner cell mass and trophoblast, with a **fluid-filled blastocoel cavity**. - The solid, compacted structure of the morula is no longer present.
Question 7: Arrange the cells according to their positions from the basal layer towards the lumen in the seminiferous tubules:- 1. Spermatogonia 2. Primary spermatocyte 3. Spermatid 4. Spermatozoa
- A. 2,1,3,4
- B. 1,2,3,4 (Correct Answer)
- C. 1,3,2,4
- D. 4,3,2,1
Explanation: ***1,2,3,4*** - This sequence accurately represents the **developmental progression of male germ cells** from the basal lamina towards the lumen of the seminiferous tubule [1], [2]. - **Spermatogonia** are stem cells located near the basal lamina [1], which then differentiate into **primary spermatocytes**, followed by **spermatids**, and finally maturing into **spermatozoa** that are released into the lumen [2]. *2,1,3,4* - This order is incorrect because **primary spermatocytes** develop from spermatogonia [2], meaning spermatogonia should precede primary spermatocytes in the sequence. - The initial cell in the spermatogenic lineage is the **spermatogonium**, found at the base of the tubule [1]. *1,3,2,4* - This sequence is incorrect as **primary spermatocytes** undergo meiosis to form secondary spermatocytes, which then become spermatids [2]. - Therefore, **spermatids** develop *after* primary spermatocytes, not before them. *4,3,2,1* - This order is a reversal of the actual developmental process and spatial arrangement within the seminiferous tubule. - **Spermatozoa** are the most mature cells and are found closest to the lumen [1], while **spermatogonia** are located at the basal layer [1].
Question 8: 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].
Question 9: Which of the following organisms show parthenogenesis?
- A. Ascaris
- B. Trichuris
- C. Strongyloides (Correct Answer)
- D. Ancylostoma
Explanation: ***Correct: Strongyloides*** - *Strongyloides stercoralis* is known for its complex life cycle, which includes **parthenogenetic reproduction** in the free-living female generation. - The parasitic females can produce larvae directly through **parthenogenesis (reproduction without fertilization)**, enabling autoinfection. - This unique ability allows the parasite to **reproduce without a male** within and outside the human host, leading to persistent infections and hyperinfection syndrome. *Incorrect: Ascaris* - *Ascaris lumbricoides* reproduces sexually, requiring **both male and female worms** for fertilization and egg production. - There is no evidence of parthenogenetic reproduction in *Ascaris*. *Incorrect: Trichuris* - *Trichuris trichiura* (whipworm) is a **dioecious** (sexually reproducing) nematode where **separate male and female worms** are required for reproduction. - Parthenogenesis is not observed in the life cycle of *Trichuris*. *Incorrect: Ancylostoma* - *Ancylostoma duodenale* (hookworm) reproduces sexually in the human intestine. - Requires **male and female worms** to produce fertilized eggs; parthenogenesis does not occur.
Question 10: Which one of the following tests should be applied to compare mean haemoglobin level of two groups of antenatal mothers?
- A. Analysis of variance
- B. Chi-square test
- C. Unpaired t-test (Correct Answer)
- D. Paired t-test
Explanation: ***Unpaired t-Test*** - The **unpaired t-test** is used to compare the means of **two independent groups** on a continuous variable, such as hemoglobin levels. - Antenatal mothers in two distinct groups are independent, and **hemoglobin level is a continuous variable**, making this the appropriate choice. *Analysis of variance* - **ANOVA** (Analysis of Variance) is used to compare the means of **three or more independent groups**. - Since there are only **two groups** being compared, ANOVA is not the most efficient or appropriate test. *Chi-square test* - The **Chi-square test** is used to analyze the association between **two categorical variables**. - Hemoglobin level is a **continuous variable**, not categorical, so this test is not suitable for comparing means. *Paired t-test* - The **paired t-test** is used to compare the means of **two related groups** or the same group measured at two different times (e.g., before and after an intervention). - The two groups of antenatal mothers are **independent**, not paired or related.
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