Reproductive Physiology — MCQs
Hormone predominantly secreted after 14 days that acts on the endometrium is?
A major causal factor in some cases of hypogonadism is:
Hormonal secretions are tightly controlled by the time of day due to an inbuilt biological clock in human body. This rhythmic secretion is controlled by:
Increased LH secretion just before ovulation is due to
Day 20 of menstrual cycle falls under which phase?
By which mechanism do LH and FSH primarily return to baseline levels after ovulation?
A 24-year-old woman with a married life of 4 years visits an infertility clinic with a history of recurrent abortion. On further workup, she is found to have a septate uterus. Which surgery has the best reproductive outcome?
Which of the following structures has the function of capacitation?
What is the most common site for ectopic pregnancies?
Consider the following statements regarding HCG : 1. HCG is a glycoprotein with two subunits α and β. 2. HCG levels reach the maximum between the 60th and 70th day in a normal pregnancy. 3. HCG is secreted by the syncytiotrophoblast. Which of the statements given above is/are correct ?
Reproductive Physiology Indian Medical PG Practice Questions and MCQs
Question 1: Hormone predominantly secreted after 14 days that acts on the endometrium is?
- A. Progesterone (Correct Answer)
- B. Estrogen
- C. LH
- D. FSH
Explanation: ***Progesterone*** - After **ovulation** (around day 14 of a typical 28-day cycle), the **corpus luteum** forms and begins secreting large amounts of progesterone. - Progesterone's primary role is to prepare the **endometrium** for potential implantation by making it secretory and vascularized. *Estrogen* - Estrogen levels are highest during the **proliferative phase** (days 1-14), promoting endometrial growth and thickening. - While present after day 14, its predominant role shifts to preparing the uterus, but not as the *main* hormone secreted to support the post-ovulatory endometrium. *LH (Luteinizing Hormone)* - LH is crucial for triggering **ovulation** itself, with a surge occurring just before day 14. - After ovulation, LH levels decrease and its primary role is not direct endometrial modification. *FSH (Follicle-Stimulating Hormone)* - FSH is primarily active in the **follicular phase** (days 1-14), stimulating ovarian follicle growth. - Its levels decrease after ovulation, and it does not directly regulate endometrial changes in the post-ovulatory period.
Question 2: A major causal factor in some cases of hypogonadism is:
- A. Reduced secretion of gonadotropin-releasing hormone (GnRH) (Correct Answer)
- B. Excess secretion of testicular activin by Sertoli cells
- C. Hypersecretion of pituitary LH and FSH as the result of increased GnRH
- D. Failure of the hypothalamus to respond to testosterone
Explanation: ***Reduced secretion of gonadotropin-releasing hormone (GnRH)*** - **Hypogonadotropic hypogonadism** is characterized by low levels of LH and FSH due to inadequate GnRH secretion from the hypothalamus, leading to decreased testosterone production. - This can be caused by various factors, including genetic conditions, hypothalamic tumors, or functional suppression from stress or severe illness. *Excess secretion of testicular activin by Sertoli cells* - **Activin** promotes FSH synthesis and secretion from the pituitary but is not a primary cause of hypogonadism. - While disruptions in activin/inhibin balance can affect spermatogenesis, it doesn't directly cause a systemic hypogonadal state through its direct effect on GnRH or gonadal function. *Hypersecretion of pituitary LH and FSH as the result of increased GnRH* - **Hypersecretion of LH and FSH** in response to increased GnRH would lead to **hypergonadism**, or at least eugonadism, not hypogonadism. - This scenario would stimulate excessive testosterone production, the opposite of hypogonadism. *Failure of the hypothalamus to respond to testosterone* - The hypothalamus, as well as the pituitary, are sensitive to **negative feedback from testosterone** to regulate GnRH and gonadotropin release. - A failure to respond to testosterone would typically lead to **increased GnRH and gonadotropin secretion** (as the feedback loop is broken), resulting in higher testosterone levels, which contradicts hypogonadism.
Question 3: Hormonal secretions are tightly controlled by the time of day due to an inbuilt biological clock in human body. This rhythmic secretion is controlled by:
- A. Ventrolateral nucleus
- B. Supraoptic nucleus
- C. Suprachiasmatic nucleus (Correct Answer)
- D. Posterolateral nucleus
Explanation: ***Suprachiasmatic nucleus*** - The **suprachiasmatic nucleus (SCN)**, located in the hypothalamus, is the primary pacemaker of the body's **circadian rhythms**, controlling the timing of hormonal secretions, sleep-wake cycles, and other daily oscillations. - It receives direct input from the **retina** about light-dark cycles, allowing it to synchronize the body's internal clock with the external environment. *Ventrolateral nucleus* - The **ventrolateral preoptic nucleus (VLPO)** is involved in **sleep regulation** and promoting non-REM sleep, but it does not act as the primary circadian pacemaker. - It receives input from the SCN and collaborates in regulating sleep, but its role is primarily inhibitory to wakefulness. *Supraoptic nucleus* - The **supraoptic nucleus** is primarily involved in the production and secretion of **vasopressin (ADH)** and **oxytocin**, which are neurohormones regulating fluid balance and social bonding, respectively. - It does not directly control the rhythmic aspect of general hormonal secretions or act as the central circadian clock. *Posterolateral nucleus* - This term is less commonly used in the context of circadian rhythm control; however, if referring to a thalamic nucleus, the **posterolateral nucleus** is generally associated with sensory processing, particularly somatosensory information. - It has no known role as a central pacemaker for hormonal secretions or circadian rhythms.
Question 4: Increased LH secretion just before ovulation is due to
- A. Positive feed-back by FSH
- B. Positive feed-back by progesterone
- C. Positive feed-back by relaxin
- D. Positive feed-back by estrogen (Correct Answer)
Explanation: ***Positive feed-back by estrogen*** - The surge in **estrogen** from the dominant follicle during the late follicular phase stimulates the hypothalamus and anterior pituitary. - This high level of estrogen switches from negative to **positive feedback**, leading to a dramatic increase in **GnRH** and subsequently **LH** secretion. *Positive feed-back by FSH* - While **FSH** plays a role in follicular development, its primary function is to stimulate estrogen production, not directly trigger the LH surge via positive feedback. - FSH levels actually decline during the late follicular phase as estrogen levels rise, before a small secondary surge alongside LH. *Positive feed-back by progesterone* - **Progesterone** levels are low before ovulation and begin to rise significantly only after the **LH surge** and ovulation, secreted primarily by the corpus luteum. - While progesterone can contribute to a further LH surge in some contexts, it is not the primary initiator of the pre-ovulatory LH surge. *Positive feed-back by relaxin* - **Relaxin** is primarily involved in relaxing pelvic ligaments and softening the cervix, especially during pregnancy. - It does not play a role in the **positive feedback mechanism** that triggers the pre-ovulatory LH surge.
Question 5: Day 20 of menstrual cycle falls under which phase?
- A. Menstrual phase
- B. Follicular phase
- C. Ovulation phase
- D. Luteal phase (Correct Answer)
Explanation: ***Luteal phase*** - The **luteal phase** typically starts after ovulation, around day 14, and lasts until menstruation begins, usually day 28 of a 28-day cycle. Therefore, **day 20 falls squarely within this phase**. - During this phase, the **corpus luteum** forms and produces **progesterone**, preparing the uterus for potential pregnancy. *Menstrual phase* - The **menstrual phase** is the period of shedding of the uterine lining, typically occurring from **day 1 to day 5** of the menstrual cycle. - Day 20 is well past this phase, during which bleeding and low hormone levels are characteristic. *Follicular phase* - The **follicular phase** starts on day 1 of menstruation and lasts until ovulation, usually around **day 13-14** in a 28-day cycle. - During this phase, follicles mature under the influence of **FSH** and **estrogen** levels rise. Day 20 is beyond this period. *Ovulation phase* - The **ovulation phase** is a short period, typically around **day 14** of a 28-day cycle, when the mature egg is released from the ovary. - This phase is brief and marks the transition from the follicular to the luteal phase, so day 20 is considerably after ovulation.
Question 6: By which mechanism do LH and FSH primarily return to baseline levels after ovulation?
- A. Negative feedback on GnRH from testosterone
- B. LH surge
- C. Negative feedback on GnRH by estradiol
- D. Negative feedback on gonadotropin-releasing hormone (GnRH) by progesterone (Correct Answer)
Explanation: ***Negative feedback on GnRH by progesterone*** - After ovulation, the **corpus luteum** secretes **progesterone** (and estradiol), which exerts powerful **negative feedback** on the hypothalamus and pituitary - **Progesterone** is the **dominant hormone** in the **luteal phase** that suppresses **GnRH** pulsatility, leading to decreased secretion of both **LH** and **FSH** to baseline levels - This negative feedback maintains low gonadotropin levels throughout the luteal phase until corpus luteum regression *Negative feedback on GnRH by estradiol* - **Estradiol** does provide negative feedback, particularly in the **early-mid follicular phase**, where it primarily suppresses **FSH** secretion - In the luteal phase, estradiol works **synergistically with progesterone**, but **progesterone is the dominant feedback signal** for returning both LH and FSH to baseline after ovulation - Estradiol alone (without progesterone) triggers the **LH surge** via positive feedback at high concentrations *Negative feedback on GnRH from testosterone* - This mechanism is specific to **males**, where **testosterone** from Leydig cells provides negative feedback to regulate **GnRH**, **LH**, and **FSH** secretion - In females, testosterone plays only a minor role in feedback regulation of the hypothalamic-pituitary-gonadal axis *LH surge* - The **LH surge** is a **positive feedback** phenomenon triggered by high **estradiol** levels in the late follicular phase - This represents the **peak** of LH secretion that triggers ovulation, not a mechanism for returning LH and FSH to **baseline** levels - After the surge, LH falls due to negative feedback from progesterone and estradiol during the luteal phase
Question 7: A 24-year-old woman with a married life of 4 years visits an infertility clinic with a history of recurrent abortion. On further workup, she is found to have a septate uterus. Which surgery has the best reproductive outcome?
- A. Tompkins procedure
- B. Hysteroscopic surgery (Correct Answer)
- C. Jones procedure
- D. Strassman procedure
Explanation: ***Hysteroscopic surgery*** - This minimally invasive procedure involves resecting the **septum** using a hysteroscope, which is associated with excellent reproductive outcomes, often achieving **term pregnancy rates of 70-80%**. - It is preferred because it avoids hysterotomy (incision into the uterus), preserving uterine integrity and reducing the risk of future complications during pregnancy and delivery. *Tompkins procedure* - This procedure involves a **laparotomy and longitudinal incision** into the uterus to excise the septum, followed by closure. - While effective, it is a more invasive open surgical approach, leading to a **longer recovery time** and potentially compromising uterine integrity, increasing the risk of future uterine rupture. *Jones procedure* - The Jones procedure is also an **abdominal metroplasty** that involves excising a wedge of tissue from the fundus of the uterus, typically used for **bicornuate uteri**. - It is **highly invasive** and not the preferred method for a septate uterus due to its extensive nature and associated risks. *Strassman procedure* - The Strassman procedure is primarily used for the surgical correction of a **bicornuate uterus** or **uterus didelphys**, involving unification of the two uterine horns. - This procedure is also an **open abdominal surgery** with significant recovery time and risks, and is not applicable for a septate uterus, where the issue is a fibrous or muscular wall within a single uterine cavity.
Question 8: Which of the following structures has the function of capacitation?
- A. Male reproductive tract
- B. Vas deferens
- C. Female reproductive tract (Correct Answer)
- D. Capillary
Explanation: ***Female reproductive tract*** - **Capacitation** is a biochemical process that occurs in the **female reproductive tract** (primarily the fallopian tubes and uterus), enabling sperm to gain the ability to fertilize an egg. - This process involves the removal of **cholesterol and glycoproteins** from the sperm head membrane, which modifies its motility and prepares it for the **acrosome reaction**. - Capacitation typically takes **5-6 hours** and is essential for successful fertilization. *Male reproductive tract* - The male reproductive tract produces and stores sperm, but it is **not the site where capacitation occurs**. - Sperm are immature and unable to fertilize an egg when they leave the male reproductive tract. - Sperm only gain fertilizing capacity after exposure to the female reproductive tract environment. *Vas deferens* - The vas deferens is a tube that transports sperm from the epididymis to the ejaculatory duct. - It is a part of the male reproductive tract and does **not contribute to capacitation**. *Capillary* - Capillaries are tiny blood vessels involved in nutrient and waste exchange, entirely unrelated to sperm function or capacitation. - This option is biologically implausible in the context of reproduction.
Question 9: What is the most common site for ectopic pregnancies?
- A. Isthmus
- B. Ampulla (Correct Answer)
- C. Fimbriae
- D. Interstitial/Cornual
Explanation: ***Ampulla*** - The **ampulla** of the fallopian tube is the most common site for ectopic pregnancies, accounting for about **70-80% of all cases**. - Its **wider lumen** and **tortuous path** can delay the ovum's transit, increasing the likelihood of implantation there. *Isthmus* - The **isthmus** is the second most common site for ectopic pregnancies, accounting for about **12% of cases**. - Pregnancies in this narrow, muscular part of the tube are more prone to **early rupture** due to limited distensibility. *Fimbriae* - **Fimbrial** ectopic pregnancies are rare, accounting for approximately **5% of cases**. - These occur when the fertilized egg implants on the **finger-like projections** at the end of the fallopian tube. *Interstitial/Cornual* - **Interstitial** or **cornual** pregnancies are uncommon but serious, making up about **2-4% of ectopic pregnancies**. - They occur in the portion of the fallopian tube that passes through the **muscular wall of the uterus** and carry a higher risk of hemorrhage due to rich vascularity.
Question 10: Consider the following statements regarding HCG : 1. HCG is a glycoprotein with two subunits α and β. 2. HCG levels reach the maximum between the 60th and 70th day in a normal pregnancy. 3. HCG is secreted by the syncytiotrophoblast. Which of the statements given above is/are correct ?
- A. 2 and 3 only
- B. 1 and 2 only
- C. 1 and 3 only
- D. 1, 2 and 3 (Correct Answer)
Explanation: ***Correct: 1, 2 and 3*** - **Human Chorionic Gonadotropin (HCG)** is a **glycoprotein hormone** composed of **alpha (α) and beta (β) subunits**, making statement 1 correct - HCG is primarily secreted by the **syncytiotrophoblast** cells of the placenta, confirming statement 3 - In a normal pregnancy, HCG levels typically **peak between 60-70 days (8-10 weeks)** after the last menstrual period, supporting statement 2 - All three statements are factually accurate regarding HCG structure, secretion, and physiological levels *Incorrect: 2 and 3 only* - This option incorrectly excludes statement 1 about HCG being a glycoprotein with α and β subunits - The structural composition of HCG as a heterodimeric glycoprotein is a fundamental characteristic *Incorrect: 1 and 2 only* - This option incorrectly excludes statement 3 about syncytiotrophoblast being the source of HCG - The syncytiotrophoblast is the outer layer of the trophoblast responsible for HCG secretion *Incorrect: 1 and 3 only* - This option incorrectly excludes statement 2 about HCG peak timing during pregnancy - Understanding that HCG peaks at 8-10 weeks (60-70 days) is crucial for monitoring early pregnancy
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