Reproductive Physiology Practice Questions

Q: Which of the following are true after 28 weeks of gestation?

Viable. **Explanation:** The correct answer is **A (Viable)**. In clinical neonatology and forensic medicine, **28 weeks of gestation** is traditionally considered the threshold of **viability**. At this stage, the lungs have developed sufficiently (entering the saccular stage) to allow for gas exchange, and the central nervous system is mature enough to direct rhythmic breathing movements, giving the fetus a reasonable chance of survival outside the womb with neonatal intensive care. **Analysis of Options:** * **A. Viable:** Correct. While modern NICUs can save infants at 24 weeks, 28 weeks remains the standard benchmark for viability in many medical-legal contexts and textbooks. * **B. > 1000 gm:** Incorrect. While many 28-week fetuses approach this weight, the average weight at 28 weeks is approximately **1000 to 1100 grams**. However, weight is a variable growth parameter, whereas "viability" is a developmental milestone. * **C. L/S Ratio > 2:** Incorrect. An **L/S ratio > 2** typically indicates mature lungs and is usually achieved around **34–35 weeks** of gestation. At 28 weeks, the ratio is generally much lower, indicating a high risk of Respiratory Distress Syndrome (RDS). * **D. Type II Pneumocytes present:** Incorrect as a specific marker for 28 weeks. Type II pneumocytes (which produce surfactant) actually appear much earlier, around **20–24 weeks** of gestation. **Clinical Pearls for NEET-PG:** * **Surfactant production** begins at 20 weeks but reaches adequate levels for independent breathing only after 34 weeks. * **Glucocorticoids** (Betamethasone/Dexamethasone) are administered to the mother if preterm birth is expected before 34 weeks to accelerate surfactant production. * **Stages of Lung Development:** Embryonic → Pseudoglandular → Canalicular (16-26 wks) → Saccular (26 wks to birth) → Alveolar (Postnatal).

Q: Decidualization of the endometrium is primarily caused by which hormone?

Progesterone. **Explanation:** **Decidualization** is the process by which endometrial stromal cells transform into large, polygonal, glycogen-rich cells (decidual cells) to provide a supportive environment for the implanting embryo. **Why Progesterone is correct:** Progesterone is the "hormone of pregnancy." Following ovulation, the corpus luteum secretes high levels of progesterone. This hormone acts on the estrogen-primed endometrium to initiate the secretory phase. Progesterone triggers the differentiation of stromal fibroblasts into decidual cells, increases vascularity (spiral artery development), and stimulates uterine gland secretion. If implantation occurs, progesterone levels remain high to maintain this decidua; without it, the decidua sheds (menstruation). **Why other options are incorrect:** * **Estrogen:** While estrogen is essential for the **proliferative phase** (thickening the endometrial lining), it does not cause decidualization. It "primes" the tissue so that progesterone can act effectively. * **Inhibin:** Produced by the granulosa cells (Inhibin B) and corpus luteum (Inhibin A), its primary role is the negative feedback inhibition of FSH secretion from the anterior pituitary. * **FSH:** This gonadotropin is responsible for the recruitment and maturation of ovarian follicles; it has no direct effect on the morphological transformation of the endometrium. **NEET-PG High-Yield Pearls:** * **Decidua Basalis:** The part of the decidua at the implantation site that forms the maternal component of the placenta. * **Arias-Stella Reaction:** A benign change in endometrial glands (hypersecretory phenotype) due to high progesterone, often seen in ectopic pregnancy; it can be mistaken for malignancy. * **Window of Implantation:** Occurs approximately 6–10 days after the LH surge (Days 20–24 of a typical cycle) when progesterone levels are peak.

Q: Ovulation occurs after the extrusion of which of the following?

First polar body. ### Explanation **Correct Answer: C. First polar body** **The Core Concept:** Oogenesis is a discontinuous process characterized by specific arrests. All primary oocytes are arrested in **Prophase of Meiosis I** (specifically the diplotene stage) since fetal life. Just before ovulation, the **LH surge** triggers the completion of Meiosis I. This division is unequal, resulting in a large **secondary oocyte** and a small, non-functional **first polar body**. Therefore, at the time of ovulation, the egg is technically a secondary oocyte that has already extruded the first polar body. **Analysis of Options:** * **A. Primary oocyte:** This is incorrect because the primary oocyte must complete Meiosis I to become a secondary oocyte before it can be released from the follicle. * **B. Female pronucleus:** This is incorrect as the pronucleus only forms *after* fertilization occurs and the second meiotic division is completed. * **D. Second polar body:** This is incorrect because the extrusion of the second polar body occurs only **after fertilization** (when the sperm penetrates the secondary oocyte), triggering the completion of Meiosis II. **High-Yield NEET-PG Pearls:** * **Arrest Points:** 1. **First Arrest:** Prophase I (Diplotene) — maintained by Oocyte Maturation Inhibitor (OMI). 2. **Second Arrest:** Metaphase II — occurs at ovulation and is only completed if fertilization happens. * **The "M" Rule:** Ovulation occurs at **M**etaphase II; the **M**eiosis II is completed only if **M**eets a sperm. * **Chromosomal Status:** The secondary oocyte (post-ovulation) is **haploid (23, X)** but contains double the DNA amount (2n) until the second polar body is shed.

Q: What is the main hormone that acts upon the uterus to initiate labor?

Oxytocin. **Explanation:** **Correct Answer: A. Oxytocin** Oxytocin is the primary hormone responsible for the initiation and maintenance of uterine contractions during labor. It acts via G-protein coupled receptors on the myometrium, increasing intracellular calcium levels to trigger muscle contraction. While the fetus and placenta contribute to the hormonal milieu, the maternal posterior pituitary releases pulsatile oxytocin, and the uterus itself increases its expression of oxytocin receptors (up to 200-fold) near term, making it highly sensitive to even low levels of the hormone. **Why other options are incorrect:** * **B. Estrogen:** Estrogen levels rise toward the end of pregnancy to "prime" the uterus. It increases the synthesis of gap junctions and oxytocin receptors, but it does not directly initiate the rhythmic contractions of labor. * **C. Progesterone:** Known as the "hormone of pregnancy," progesterone maintains uterine quiescence by inhibiting contractions. Labor is preceded by a functional "progesterone withdrawal," but the hormone itself does not initiate labor. * **D. Cortisol:** In many species (like sheep), fetal cortisol triggers the onset of labor. In humans, while the fetal hypothalamic-pituitary-adrenal (HPA) axis plays a role in increasing precursor hormones for estrogen, it is not the direct effector hormone for uterine contractions. **High-Yield Clinical Pearls for NEET-PG:** * **Ferguson’s Reflex:** This is a neuroendocrine reflex where stretching of the cervix (by the presenting part) triggers the release of oxytocin from the posterior pituitary, creating a positive feedback loop. * **Active Management of Third Stage of Labor (AMTSL):** Oxytocin (10 IU IM or 5 IU slow IV) is the drug of choice to prevent Postpartum Hemorrhage (PPH). * **Bishop Score:** Used to assess "cervical ripeness" before inducing labor with oxytocin.

Q: Sertoli cells play a key role in which of the following processes?

Spermiogenesis. **Explanation:** Sertoli cells, often referred to as "nurse cells," are essential for the maturation of male gametes. The correct answer is **Spermiogenesis**—the final stage of spermatogenesis where round spermatids transform into elongated, motile spermatozoa. Sertoli cells facilitate this by providing structural support, phagocytosing excess cytoplasm (residual bodies) from the developing spermatids, and secreting essential nutrients and regulatory proteins. **Analysis of Options:** * **A. Spermiogenesis (Correct):** Sertoli cells are directly involved in the remodeling of spermatids. They also form the **Blood-Testis Barrier**, protecting developing sperm from the immune system. * **B. Testosterone secretion:** This is the primary function of **Leydig cells** (interstitial cells), located in the connective tissue between seminiferous tubules, under the influence of LH. * **C. Secretion of seminal fluid:** The majority of seminal fluid is produced by the **seminal vesicles** (~60%) and the **prostate gland** (~30%), not the Sertoli cells. * **D. Production of germ cells:** Germ cells (spermatogonia) are derived from primordial germ cells. Sertoli cells do not produce them but rather provide the microenvironment required for their division and differentiation. **High-Yield Facts for NEET-PG:** * **Inhibin B:** Secreted by Sertoli cells to provide negative feedback on **FSH** secretion. * **Androgen Binding Protein (ABP):** Secreted by Sertoli cells to maintain high local concentrations of testosterone within the tubules. * **Anti-Müllerian Hormone (AMH):** Produced by fetal Sertoli cells to cause regression of Müllerian ducts. * **Blood-Testis Barrier:** Formed by **tight junctions** between adjacent Sertoli cells.

Q: In postmenopausal women, estrogen is metabolized mostly into which of the following?

Estrone. **Explanation:** In postmenopausal women, the primary source of estrogen shifts from the ovaries to peripheral tissues. The correct answer is **Estrone (E1)** because, after menopause, ovarian follicular activity ceases, leading to a drastic decline in Estradiol (E2) levels. Instead, androgens (primarily androstenedione) secreted by the adrenal cortex and ovarian stroma are converted into **Estrone** via the enzyme **aromatase** in peripheral adipose tissue. **Analysis of Options:** * **Estrone (E1):** The dominant estrogen in **postmenopausal** women. It is less potent than estradiol and is formed via peripheral aromatization. * **Estradiol (E2):** The most potent and dominant estrogen during the **reproductive years** (pre-menopausal). It is primarily produced by the granulosa cells of the developing follicles. * **Estriol (E3):** The least potent estrogen and the dominant form during **pregnancy**, produced primarily by the feto-placental unit. * **Androstenedione:** This is an **androgen precursor**, not an estrogen. While it is the substrate for estrone production in postmenopausal women, it is not the metabolite of estrogen itself. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Order:** Estradiol (E2) > Estrone (E1) > Estriol (E3). * **Source of E1:** In obese postmenopausal women, increased adipose tissue leads to higher peripheral aromatization, resulting in elevated estrone levels, which is a significant risk factor for **endometrial carcinoma**. * **LH/FSH Ratio:** In menopause, both LH and FSH rise due to loss of negative feedback, but **FSH increases more significantly** (FSH > LH) because of the loss of Inhibin.

Q: Which of the following statements about estrogen action is FALSE?

Stimulates osteoclasts.. ### Explanation The correct answer is **B. Stimulates osteoclasts.** **1. Why Option B is False (The Correct Answer):** Estrogen is fundamentally **bone-protective**. It does not stimulate osteoclasts; rather, it **inhibits osteoclast activity** and promotes their apoptosis. The primary mechanism involves the RANK/RANKL pathway: estrogen increases the production of **Osteoprotegerin (OPG)**, a decoy receptor that binds to RANKL, preventing it from activating the RANK receptor on osteoclasts. This inhibits bone resorption. This is why post-menopausal women (who have low estrogen) are at a high risk for osteoporosis. **2. Analysis of Other Options:** * **A. Stimulates secondary sex characteristics:** This is a primary function of estrogen. It promotes breast development (ductal growth), female fat distribution (hips/thighs), and the maturation of the vagina and uterus. * **C. Decreases LDL cholesterol:** Estrogen has a cardioprotective effect. It increases HDL ("good" cholesterol) and decreases LDL ("bad" cholesterol) by increasing the expression of LDL receptors in the liver, enhancing LDL clearance. * **D. Increases blood coagulability:** Estrogen is **pro-thrombotic**. It increases the hepatic synthesis of clotting factors (II, VII, IX, X, and fibrinogen) and decreases anticoagulants like Protein S and Antithrombin III. This explains the increased risk of DVT/stroke in women taking Oral Contraceptive Pills (OCPs). **3. NEET-PG High-Yield Pearls:** * **Bone Effect:** Estrogen causes the **closure of epiphyseal plates** in both males and females, ending linear growth. * **Cervical Mucus:** Under estrogen influence, cervical mucus becomes thin, watery, and alkaline, showing a characteristic **"Fern pattern"** on microscopy. * **Temperature:** Unlike progesterone (which is thermogenic), estrogen does not increase basal body temperature.

Q: What type of estrogen is found in the highest concentration in adult females?

Estradiol. **Explanation:** In adult females of reproductive age, **Estradiol (E2)** is the most potent and abundant form of estrogen. It is primarily synthesized in the ovaries by the granulosa cells through the aromatization of androgens. Its concentration fluctuates during the menstrual cycle, peaking just before ovulation. **Analysis of Options:** * **Estradiol (E2):** The "estrogen of the reproductive years." It is the most biologically active form and is responsible for the development of secondary sexual characteristics and the regulation of the menstrual cycle. * **Estrone (E1):** The "estrogen of menopause." It is a weaker estrogen produced mainly in adipose tissue via peripheral conversion. It is the predominant circulating estrogen after menopause. * **Estriol (E3):** The "estrogen of pregnancy." It is the least potent form and is produced in large quantities by the placenta. High levels of E3 serve as an indicator of fetal well-being. **NEET-PG High-Yield Pearls:** 1. **Potency Order:** Estradiol (E2) > Estrone (E1) > Estriol (E3). 2. **Source:** Estradiol is produced by the **Aromatase** enzyme (induced by FSH) in the ovary. 3. **Clinical Correlation:** In Polycystic Ovary Syndrome (PCOS), there is an increased E1:E2 ratio due to the peripheral conversion of androstenedione to estrone in adipose tissue. 4. **Mnemonic:** Remember the numbers: **E1** (One/m**O**ne-opause), **E2** (Two/Ovaries-**T**wo), **E3** (Three/Placenta-**T**hree).

Q: Time taken for capacitation of sperms is?

6-8 hours. **Explanation:** **Capacitation** is the final stage of sperm maturation that occurs within the female reproductive tract (primarily in the uterus and fallopian tubes). It involves the removal of the protective glycoprotein coat and seminal plasma proteins from the plasma membrane overlying the acrosome. This process is essential because it increases sperm motility (hyperactivation) and allows the sperm to undergo the acrosome reaction upon reaching the oocyte. 1. **Why 6-8 hours is correct:** Standard medical textbooks (including Williams Obstetrics and Dutta’s Textbook of Gynecology) state that the physiological process of capacitation takes approximately **7 hours** on average. Therefore, the range of **6-8 hours** is the most accurate representation of the time required for these biochemical changes to complete. 2. **Why other options are incorrect:** * **2-4 and 4-6 hours:** These durations are too short for the complete removal of the decapacitation factors and the necessary influx of calcium ions required for hyperactivation. * **8-10 hours:** While sperm can survive in the female tract for up to 48–72 hours, the specific process of becoming "capacitated" is usually completed well before 10 hours. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Capacitation:** Female reproductive tract (Uterus and Fallopian tube). * **Key Change:** Increase in membrane permeability to **Calcium (Ca²⁺)**, leading to increased cAMP levels and hypermotility. * **In-Vitro Fertilization (IVF):** In IVF, capacitation is artificially induced by washing the sperm in special media to remove inhibitory seminal proteins. * **Sequence of Events:** Capacitation → Acrosome Reaction → Fusion with Oocyte (Zona Pellucida).

Q: Galactokinesis means:

Ejection of milk. **Explanation:** Lactation is a complex physiological process divided into four distinct stages. Understanding the terminology is crucial for NEET-PG, as these terms are frequently tested. **1. Why "Ejection of milk" is correct:** **Galactokinesis** refers to the discharge or ejection of milk from the mammary alveoli into the ducts and then out through the nipple. This process is primarily mediated by the **"Let-down reflex."** When the infant suckles, it triggers the release of **Oxytocin** from the posterior pituitary. Oxytocin causes the contraction of myoepithelial cells surrounding the alveoli, forcing milk out. **2. Why the other options are incorrect:** * **Synthesis of milk (Mammogenesis/Lactogenesis I):** This refers to the structural development of the mammary glands and the initial biochemical changes to produce milk components. * **Secretion of milk (Lactogenesis II):** This is the onset of copious milk secretion following delivery, triggered by the sudden withdrawal of estrogen and progesterone and the action of **Prolactin**. * **Sustaining lactation (Galactopoiesis):** This refers to the maintenance of established lactation. It requires a continuous supply of Prolactin (stimulated by regular suckling) and the periodic emptying of the breasts. **High-Yield Clinical Pearls for NEET-PG:** * **Prolactin** = Milk **Production** (Anterior Pituitary). * **Oxytocin** = Milk **Ejection** (Posterior Pituitary). * **Galactopoiesis** is maintained by the **suckling reflex**; if the breast is not emptied, the Feedback Inhibitor of Lactation (FIL) peptide accumulates, stopping further production. * **Bromocriptine** (Dopamine agonist) is the drug of choice to suppress lactation if medically indicated.

Question 1

Which of the following are true after 28 weeks of gestation?

Accepted Answer

Viable

Answer

> 1000 gm

Answer

Lecithin/Sphingomyelin ratio > 2

Answer

Type II pneumocytes present

Question 2

Decidualization of the endometrium is primarily caused by which hormone?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

Inhibin

Answer

Follicle Stimulating Hormone (FSH)

Question 3

Ovulation occurs after the extrusion of which of the following?

Accepted Answer

First polar body

Answer

Primary oocyte

Answer

Female pronucleus

Answer

Second polar body

Question 4

What is the main hormone that acts upon the uterus to initiate labor?

Accepted Answer

Oxytocin

Answer

Estrogen

Answer

Progesterone

Answer

Cortisol

Question 5

Sertoli cells play a key role in which of the following processes?

Accepted Answer

Spermiogenesis

Answer

Testosterone secretion

Answer

Secretion of seminal fluid

Answer

Production of germ cells

Question 6

In postmenopausal women, estrogen is metabolized mostly into which of the following?

Accepted Answer

Estrone

Answer

Estriol

Answer

Estradiol

Answer

Androstenedione

Question 7

Which of the following statements about estrogen action is FALSE?

Accepted Answer

Stimulates osteoclasts.

Answer

Stimulates secondary sex characteristics in females.

Answer

Decreases LDL cholesterol.

Answer

Increases blood coagulability.

Question 8

What type of estrogen is found in the highest concentration in adult females?

Accepted Answer

Estradiol

Answer

Estrone

Answer

Estriol

Answer

None

Question 9

Time taken for capacitation of sperms is?

Accepted Answer

6-8 hours

Answer

2-4 hours

Answer

4-6 hours

Answer

8-10 hours

Question 10

Galactokinesis means:

Accepted Answer

Ejection of milk

Answer

Sustaining lactation

Answer

Secretion of milk

Answer

Synthesis of milk

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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