Reproductive Physiology Practice Questions

Q: Which hormone is required for late-stage development of antral follicles?

FSH. **Explanation:** The development of ovarian follicles occurs in two distinct phases: the gonadotropin-independent phase and the **gonadotropin-dependent phase**. While early follicular growth (up to the pre-antral stage) is regulated by local growth factors, the transition to and maturation of the **antral follicle** (late-stage development) is strictly dependent on **Follicle-Stimulating Hormone (FSH)**. FSH binds to receptors on granulosa cells, stimulating their proliferation and the expression of the aromatase enzyme. This process is essential for the formation of the antrum (fluid-filled cavity) and the selection of the dominant follicle. Without FSH, antral follicles undergo atresia. **Analysis of Incorrect Options:** * **Androstenedione (A):** This is an androgen precursor produced by theca cells under LH influence. While it serves as a substrate for estrogen synthesis, high levels can actually promote follicular atresia rather than development. * **LH (C):** LH primarily acts on theca cells to produce androgens. While LH is crucial for the final maturation of the *dominant* follicle and triggers ovulation, FSH is the primary driver for the general development of the antral cohort. * **Estradiol (D):** Estradiol is a product of follicular development (via the Two-Cell, Two-Gonadotropin theory). While it exerts positive feedback on the granulosa cells, it is not the primary hormone "required" to initiate or sustain late-stage antral growth. **High-Yield Clinical Pearls for NEET-PG:** * **Two-Cell, Two-Gonadotropin Theory:** LH stimulates **Theca cells** (produce Androgens); FSH stimulates **Granulosa cells** (convert Androgens to Estrogens via Aromatase). * **FSH Window:** The period during the early follicular phase when FSH levels rise above a threshold to "rescue" a cohort of antral follicles from apoptosis. * **LH Surge:** Occurs 24–36 hours before ovulation; it is the reliable predictor of the mid-cycle surge.

Q: Which of the following is NOT an effect of estrogen?

Reduces HDL. Estrogen exerts significant effects on lipid metabolism and bone density, which are crucial for understanding cardiovascular and skeletal health in women. **Explanation of the Correct Answer:** **Option A (Reduces HDL)** is the correct answer because it is a **false statement**. Estrogen actually **increases HDL** (High-Density Lipoprotein), the "good cholesterol." It does this by increasing the synthesis of Apolipoprotein A-I and decreasing the activity of hepatic lipase, which slows the degradation of HDL particles. This cardioprotective effect explains why premenopausal women have a lower risk of atherosclerosis compared to men of the same age. **Explanation of Incorrect Options:** * **Option B (Reduces LDL):** Estrogen **decreases LDL** (the "bad cholesterol") by increasing the expression of LDL receptors in the liver, leading to enhanced clearance of LDL from the blood. * **Option C (Increases triglyceride):** Estrogen **increases plasma triglycerides** by stimulating the production of VLDL (Very Low-Density Lipoprotein) in the liver. This is a known side effect of oral estrogen therapy. * **Option D (Reduces bone resorption):** Estrogen is vital for bone health. It inhibits osteoclast activity (by increasing OPG and decreasing RANKL) and promotes osteoclast apoptosis, thereby **reducing bone resorption**. This is why estrogen deficiency in menopause leads to osteoporosis. **High-Yield Facts for NEET-PG:** * **Lipid Profile:** Estrogen = ↑ HDL, ↓ LDL, ↑ Triglycerides. * **Bone:** Estrogen maintains bone density by inhibiting **Interleukin-6 (IL-6)**, a potent stimulator of osteoclasts. * **Coagulation:** Estrogen increases the synthesis of clotting factors (II, VII, IX, X) and decreases Antithrombin III, explaining the pro-thrombotic risk of OCPs.

Q: After bilateral vasectomy, which of the following substances will be deficient?

None. **Explanation:** The correct answer is **D. None**. The fundamental concept here is the anatomical site of a vasectomy relative to the accessory sex glands. A vasectomy involves the ligation and excision of a small portion of the **vas deferens**. This procedure prevents the transport of spermatozoa from the epididymis to the ejaculatory ducts, resulting in **azoospermia**. However, it does not affect the production or secretion of seminal fluid from the accessory glands, as these glands enter the reproductive tract distal to the site of ligation. **Why the other options are incorrect:** * **A. Fructose:** Produced by the **seminal vesicles**. Since the seminal vesicles empty into the ejaculatory duct (distal to the vasectomy site), fructose levels in the semen remain normal. * **B. Prostaglandins:** Also primarily secreted by the **seminal vesicles**. They remain present in the ejaculate post-vasectomy. * **C. Fibrinolysin:** Secreted by the **prostate gland**. The prostatic secretions contribute to the bulk of the ejaculate and enter the prostatic urethra; thus, they are unaffected by a vasectomy. **High-Yield Facts for NEET-PG:** * **Ejaculate Composition:** Approximately 60% of semen volume comes from the seminal vesicles, 30% from the prostate, and only 10% from the vas deferens (sperm and fluid). Post-vasectomy, the volume of ejaculate decreases only marginally. * **Hormonal Status:** Vasectomy does not affect Leydig cell function; therefore, **serum Testosterone, LH, and FSH levels remain normal.** * **Post-Vasectomy Semen Analysis:** Sterility is not immediate. Patients must use contraception until two consecutive semen analyses show zero sperm count (usually after 12–20 ejaculations or 3 months).

Q: Which of the following is responsible for pubertal growth in females?

Pulsatile release of GnRH during sleep. ### Explanation **Correct Option: C. Pulsatile release of GnRH during sleep** The initiation of puberty (pubertal growth and development) is fundamentally driven by the **"reawakening" of the GnRH pulse generator** in the hypothalamus. During childhood, the Hypothalamic-Pituitary-Ovarian (HPO) axis is quiescent. The hallmark of the onset of puberty is the nocturnal, **pulsatile secretion of Gonadotropin-Releasing Hormone (GnRH)** during sleep. This pulsatility triggers the pituitary to release LH and FSH, which subsequently stimulate the ovaries to produce estrogen, leading to the development of secondary sexual characteristics and the pubertal growth spurt. **Analysis of Incorrect Options:** * **A. Decreased level of adrenal androgens:** This is incorrect. Adrenarche (the increase in adrenal androgens like DHEA) actually occurs around age 6–8 and contributes to the growth of pubic and axillary hair, not a decrease. * **B. High level of estrogen:** While estrogen is responsible for physical changes (thelarche), it is a *result* of the HPO axis activation, not the primary trigger responsible for initiating the process. * **D. Increased sensitivity of the HPO axis:** This is the opposite of what occurs. Before puberty, the hypothalamus is **exquisitely sensitive** to even tiny amounts of estrogen (negative feedback). Puberty begins when this sensitivity **decreases** (the "Gonadostat" theory), allowing GnRH levels to rise despite circulating steroids. **High-Yield NEET-PG Pearls:** * **First sign of puberty in females:** Thelarche (breast budding), followed by Pubarche, then Menarche. * **First sign of puberty in males:** Increase in testicular volume (>4 ml). * **Leptin Connection:** Adequate body fat and leptin levels are required to "permit" the pulsatile release of GnRH. * **Precocious Puberty:** Defined as the appearance of secondary sexual characteristics before age 8 in girls and age 9 in boys.

Q: Development of granules in the follicles prior to ovulation is dependent on which hormone?

LH. **Explanation:** The correct answer is **LH (Luteinizing Hormone)**. **Why LH is Correct:** The development of **follicular granules** (specifically the luteinization of granulosa cells) is a hallmark of the pre-ovulatory phase. While FSH is responsible for the initial growth of follicles and the proliferation of granulosa cells, the final maturation and the "granulation" or luteinization process—where cells accumulate lipid droplets and yellow pigment (lutein)—is triggered by the **LH surge**. This process prepares the follicle for ovulation and the subsequent formation of the corpus luteum. **Why Other Options are Incorrect:** * **FSH (Follicle Stimulating Hormone):** FSH is essential for the recruitment of follicles and the development of the antrum. However, it does not drive the specific "granulation" or luteinization process that occurs just prior to ovulation. * **Estrogen:** Estrogen is produced by the granulosa cells under the influence of FSH. While it exerts positive feedback to trigger the LH surge, it is a product of follicular activity rather than the primary hormone driving pre-ovulatory granulation. * **Progesterone:** Progesterone levels only begin to rise significantly *after* the LH surge has initiated luteinization. It is the primary hormone of the secretory phase, not the driver of pre-ovulatory follicular changes. **High-Yield NEET-PG Pearls:** * **Two-Cell, Two-Gonadotropin Theory:** LH acts on **Theca cells** to produce androgens (androstenedione); FSH acts on **Granulosa cells** to convert these androgens into estrogens via the enzyme *aromatase*. * **LH Surge:** Occurs approximately 24–36 hours before ovulation. It is the reliable predictor of ovulation used in home kits. * **Meiosis I:** The LH surge is also responsible for the completion of Meiosis I in the primary oocyte, arresting it again in Metaphase of Meiosis II.

Q: True about the proliferative phase of the endometrium is:

All of the above. The **Proliferative Phase** (also known as the Estrogenic or Follicular phase) occurs under the influence of estrogen secreted by the developing ovarian follicles. It typically lasts from day 5 to day 14 of the menstrual cycle. **Explanation of Options:** * **Option A (Timing):** Following menstruation, the endometrium is thin. Re-epithelialization begins as early as day 4-5. The proliferation proceeds rapidly, increasing the endometrial thickness from roughly 1 mm to 3-5 mm by the time of ovulation. * **Option B (Morphology):** During this phase, the endometrial glands are **simple, straight tubules** lined by a regular, columnar epithelium. They do not show the tortuosity or secretory activity (vacuoles) characteristic of the later secretory phase. * **Option C (Vascularity):** Estrogen promotes significant angiogenesis. There is **intense hyperemia** (increased blood flow) and stromal proliferation to support the growing tissue, preparing it for potential implantation. Since all three statements accurately describe the physiological changes during this phase, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Dominant Hormone:** Estrogen (specifically Estradiol). * **Histological Hallmark:** Presence of **mitotic figures** in both the glandular epithelium and the stroma. * **Comparison:** In the **Secretory Phase** (Progesterone-dominant), glands become "corkscrew" shaped or serrated, and sub-nucleolar vacuoles appear. * **Clinical Correlation:** Anovulatory cycles result in a persistent proliferative phase (due to lack of progesterone), which can lead to endometrial hyperplasia.

Q: Testosterone is secreted by:

Leydig cells. **Explanation:** **Correct Answer: A. Leydig cells** Leydig cells (also known as interstitial cells of Leydig) are located in the connective tissue between the seminiferous tubules. Their primary function is the synthesis and secretion of **testosterone** in response to **Luteinizing Hormone (LH)** from the anterior pituitary. LH binds to G-protein coupled receptors on Leydig cells, increasing cAMP and activating protein kinase A, which initiates the conversion of cholesterol to testosterone. **Analysis of Incorrect Options:** * **B. Sertoli cells:** Located within the seminiferous tubules, these are "nurse cells." They do not secrete testosterone; instead, they secrete **Androgen Binding Protein (ABP)**, Inhibin B, and Anti-Müllerian Hormone (AMH). They support spermatogenesis under the influence of FSH. * **C. Cowper’s gland:** Also known as bulbourethral glands, these secrete a clear, alkaline pre-ejaculate fluid that lubricates the urethra and neutralizes acidic urine residue. They have no endocrine function. * **D. Intermediate cells:** This is a non-specific term and not a recognized site for androgen synthesis in the male reproductive system. **High-Yield Clinical Pearls for NEET-PG:** * **LH acts on Leydig cells** (Mnemonic: **L**H = **L**eydig). * **FSH acts on Sertoli cells** (Mnemonic: **F**SH = **S**ertoli). * **Blood-Testis Barrier:** Formed by tight junctions between Sertoli cells. * **Rate-limiting step:** The conversion of cholesterol to pregnenolone by the enzyme *cholesterol side-chain cleavage enzyme* (P450scc) is the key regulated step in testosterone production. * **Testosterone levels:** Highest in the early morning due to diurnal variation.

Q: The Y chromosome carries a gene on its short arm that codes for what?

Testes-determining factor (TDF). ### Explanation The correct answer is **Testes-determining factor (TDF)**. **1. Why TDF is Correct:** The sex of an individual is determined by the presence or absence of the **SRY gene** (*Sex-determining Region of the Y chromosome*), located on the **short arm (p arm)** of the Y chromosome. This gene codes for a protein called the **Testes-determining factor (TDF)**. TDF acts as a master transcription factor that triggers the undifferentiated primordial gonads to differentiate into **testes**. Once the testes are formed, they begin secreting hormones (Testosterone and MIF) that drive male phenotypic development. **2. Why Other Options are Incorrect:** * **Testosterone (A):** This is a steroid hormone secreted by the **Leydig cells** of the fetal testes, not directly coded by a gene on the Y chromosome. Its production is a *downstream effect* of TDF action. * **Mullerian Inhibiting Factor (B):** Also known as Anti-Mullerian Hormone (AMH), it is a glycoprotein secreted by **Sertoli cells**. While its production is triggered by the development of testes, the gene for MIF is actually located on **Chromosome 19**. * **Progesterone (D):** This is a precursor for other steroid hormones and a primary female reproductive hormone secreted by the corpus luteum and placenta. It is not Y-chromosome dependent. **3. High-Yield Clinical Pearls for NEET-PG:** * **SRY Gene Location:** Short arm of Y chromosome (Yp11.3). * **Developmental Timeline:** Gonadal differentiation occurs around the **6th–7th week** of gestation. * **MIF Function:** Causes regression of Paramesonephric (Mullerian) ducts. * **Testosterone Function:** Stimulates development of Mesonephric (Wolffian) ducts into the internal male genitalia (Epididymis, Vas deferens, Seminal vesicles). * **Dihydrotestosterone (DHT):** Responsible for the development of external male genitalia and the prostate.

Q: In the absence of pregnancy, for how many days does the corpus luteum function?

12 to 14 days. **Explanation** The correct answer is **12 to 14 days (Option C)**. **Underlying Medical Concept:** The menstrual cycle consists of a variable follicular phase and a remarkably constant **luteal phase**. Following ovulation, the remains of the Graafian follicle transform into the **corpus luteum** under the influence of Luteinizing Hormone (LH). The corpus luteum functions as a temporary endocrine gland, secreting progesterone and estrogen to prepare the endometrium for implantation. In a non-pregnant cycle, the corpus luteum has a fixed lifespan of approximately **12 to 14 days**. If fertilization does not occur, the lack of Human Chorionic Gonadotropin (hCG) leads to **luteolysis** (degeneration of the corpus luteum into the corpus albicans). This causes a sharp drop in progesterone levels, triggering menstruation. **Analysis of Incorrect Options:** * **A & B (8 to 12 days):** While the corpus luteum reaches its peak functional activity around day 8–9 post-ovulation, it does not undergo complete involution this early in a healthy cycle. * **D (18 to 20 days):** This duration is too long. A functional corpus luteum beyond 14 days usually indicates the presence of hCG from a developing trophoblast (pregnancy). **High-Yield NEET-PG Pearls:** * **Constant Phase:** The luteal phase is the most constant part of the menstrual cycle (14 days). Variations in cycle length (e.g., a 35-day cycle) are due to variations in the **follicular phase**. * **Rescue Mechanism:** In pregnancy, **hCG** (an LH analog) "rescues" the corpus luteum, maintaining it until the placenta takes over progesterone production (the luteal-placental shift) at approximately 7–9 weeks of gestation. * **Hormone of Maintenance:** Progesterone is the primary hormone secreted by the corpus luteum.

Question 1

Which hormone is required for late-stage development of antral follicles?

Accepted Answer

FSH

Answer

Androstenedione

Answer

LH

Answer

Estradiol

Question 2

Which of the following is NOT an effect of estrogen?

Accepted Answer

Reduces HDL

Answer

Reduces LDL

Answer

Increases triglyceride

Answer

Reduces bone resorption

Question 3

After bilateral vasectomy, which of the following substances will be deficient?

Accepted Answer

None

Answer

Fructose

Answer

Prostaglandin

Answer

Fibrinolysin

Question 4

Which of the following is responsible for pubertal growth in females?

Accepted Answer

Pulsatile release of GnRH during sleep

Answer

Decreased level of adrenal androgens at puberty

Answer

High level of estrogen at puberty

Answer

Increased sensitivity of the HPO axis to estrogen

Question 5

Development of granules in the follicles prior to ovulation is dependent on which hormone?

Accepted Answer

LH

Answer

Estrogen

Answer

Progesterone

Answer

FSH

Question 6

True about the proliferative phase of the endometrium is:

Accepted Answer

All of the above

Answer

It starts and proceeds rapidly for 3-5 days

Answer

The glands of the functional layer are simple tubules with regular epithelium

Answer

Intense hyperemia

Question 7

Testosterone is secreted by:

Accepted Answer

Leydig cells

Answer

Sertoli cells

Answer

Cowper's gland

Answer

Intermediate cells

Question 8

The Y chromosome carries a gene on its short arm that codes for what?

Accepted Answer

Testes-determining factor (TDF)

Answer

Testosterone

Answer

Mullerian Inhibiting Factor (MIF)

Answer

Progesterone

Question 9

Which of the following statements regarding the blood-testis barrier is incorrect?

Accepted Answer

It is formed before primary spermatogenesis.

Answer

It is formed by Sertoli cells.

Answer

Rupture of the barrier can elicit an immune response to germ cells.

Answer

Germ cells are not necessary for the formation of the barrier.

Question 10

In the absence of pregnancy, for how many days does the corpus luteum function?

Accepted Answer

12 to 14 days

Answer

8 to 10 days

Answer

10 to 12 days

Answer

18 to 20 days

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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