Reproductive Physiology Practice Questions

Q: Ovulation can be diagnosed by all except:

Measuring day 14 serum progesterone. **Explanation:** The correct answer is **A (Measuring day 14 serum progesterone)** because it is timed incorrectly to diagnose ovulation. **1. Why Option A is correct (The "Except"):** In a standard 28-day menstrual cycle, ovulation occurs around Day 14. Progesterone is secreted by the **corpus luteum**, which only forms *after* ovulation has occurred. On Day 14, progesterone levels are still at basal follicular phase levels ( 3 ng/mL indicates ovulation). **2. Why the other options are incorrect (They ARE methods to diagnose ovulation):** * **Rise in Basal Body Temperature (BBT):** Progesterone is thermogenic. After ovulation, the rise in progesterone causes a 0.5°F to 1.0°F increase in BBT, resulting in a **biphasic** temperature chart. * **Study of Cervical Mucus:** Under progesterone influence (post-ovulation), cervical mucus becomes thick, cellular, and loses its elasticity (**decreased Spinnbarkeit**). It also loses the ability to "fern" on a glass slide, a change known as **anti-ferning**. * **Endometrial Histology:** A pre-menstrual endometrial biopsy showing **secretory changes** (e.g., subnuclear vacuolation) is the "gold standard" historical evidence that ovulation and subsequent progesterone production occurred. **NEET-PG High-Yield Pearls:** * **Best time for Progesterone test:** Day 21 of a 28-day cycle. * **Fern Test:** Estrogen causes ferning (positive before ovulation); Progesterone inhibits it (negative after ovulation). * **Mittelschmerz Sign:** Pelvic pain experienced by some women at the time of ovulation. * **LH Surge:** The most reliable predictor of *impending* ovulation (occurs 24–36 hours before the egg is released).

Q: During ejaculation, from which of the following structures are sperms released from their storage?

Epididymis. **Explanation:** The correct answer is **Epididymis (Option A)**. **Why it is correct:** Spermatogenesis occurs in the seminiferous tubules, but the resulting spermatozoa are immotile. They are transported to the **epididymis**, specifically the **cauda (tail) of the epididymis**, which serves as the primary site for sperm maturation and long-term storage. During ejaculation, powerful sympathetic-mediated contractions of the smooth muscle in the epididymal walls propel the stored sperm into the vas deferens. **Why other options are incorrect:** * **Vas deferens (Option B):** While the vas deferens acts as a conduit for sperm transport during ejaculation, it is not the primary storage reservoir. Its main function is the rapid peristaltic transport of sperm toward the ejaculatory ducts. * **Rete testes (Option C):** This is a network of tubules located within the hilum of the testis that collects sperm from the seminiferous tubules and drains into the efferent ductules. It is a site of passage, not storage. * **Seminal vesicle (Option D):** A common misconception is that seminal vesicles store sperm. In reality, they secrete a thick, fructose-rich alkaline fluid that constitutes about 60-70% of the total semen volume. They do **not** contain or store spermatozoa. **High-Yield NEET-PG Pearls:** * **Sperm Maturation:** Sperm acquire motility and the ability to fertilize (decapacitation factors) during their 12–24 day transit through the epididymis. * **Blood-Testis Barrier:** Formed by **Sertoli cells** (tight junctions), protecting immunogenic sperm from the immune system. * **Emission vs. Ejaculation:** Emission (movement of semen into the urethra) is mediated by **Sympathetic** nerves (T11-L2), while Ejaculation is mediated by the **Pudendal nerve** (S2-S4) causing contraction of the bulbospongiosus muscle.

Q: Estrogen is secreted by which cells?

Granulosa cells. The synthesis of estrogen in the ovary is best explained by the **Two-Cell, Two-Gonadotropin Theory**. ### Why Granulosa Cells are Correct Estrogen (specifically Estradiol) is primarily synthesized in the **Granulosa cells**. While these cells lack the enzyme *17α-hydroxylase* to produce androgens from cholesterol, they are rich in the enzyme **Aromatase**. Under the influence of **FSH**, Granulosa cells take up androgens (androstenedione and testosterone) produced by the neighboring theca cells and convert them into estrogens via aromatization. ### Why Other Options are Incorrect * **Theca interna cells:** These cells possess LH receptors and the enzyme *17α-hydroxylase*. Under **LH** stimulation, they convert cholesterol into **androgens**. They cannot produce estrogen because they lack the aromatase enzyme. * **Theca luteal cells:** These are formed after ovulation (in the corpus luteum). While they contribute to the steroidogenic pool, the primary site of estrogen synthesis remains the granulosa (now granulosa-lutein) cells. * **Theca externa cells:** This is a connective tissue layer (fibroblast-like cells) that provides structural support and vascularity to the follicle but has no endocrine/steroidogenic function. ### High-Yield NEET-PG Pearls * **Rate-limiting step:** The conversion of cholesterol to pregnenolone (by P450scc) is the rate-limiting step in steroidogenesis. * **The "Two-Cell" Summary:** 1. **Theca Interna:** LH acts $\rightarrow$ cAMP $\rightarrow$ Cholesterol to Androstenedione. 2. **Granulosa:** FSH acts $\rightarrow$ cAMP $\rightarrow$ Aromatase converts Androstenedione to Estradiol. * **Dominant Follicle:** The follicle with the highest density of FSH receptors and highest aromatase activity becomes the dominant follicle.

Q: The laboratory report shows values of gonadotropin and ovarian hormones from a blood sample taken on day 20 of the menstrual cycle of a young woman. Whether her cycle was ovulatory or not may be validly assessed by the reported serum level of:

Progesterone. **Explanation:** The correct answer is **Progesterone**. **1. Why Progesterone is the Correct Answer:** The menstrual cycle is divided into the follicular and luteal phases. Ovulation occurs around day 14, marking the transition. After ovulation, the ruptured follicle transforms into the **corpus luteum**, which primarily secretes **progesterone**. On **Day 20** (the mid-luteal phase), progesterone levels reach their peak. A serum progesterone level of **>3 ng/mL** (or ideally >10 ng/mL) is the gold standard biochemical evidence that ovulation has occurred. If the cycle were anovulatory, no corpus luteum would form, and progesterone levels would remain basal (<1 ng/mL). **2. Why Other Options are Incorrect:** * **FSH (Follicle Stimulating Hormone):** FSH peaks just before ovulation and remains low during the luteal phase due to negative feedback from estrogen and progesterone. It does not confirm ovulation. * **LH (Luteal Hormone):** While an "LH surge" triggers ovulation, it occurs around day 12–13. By day 20, LH levels have returned to baseline and cannot confirm if the egg was actually released. * **Oestradiol:** Estrogen peaks twice—once before ovulation and once during the mid-luteal phase. Because it is elevated in both phases, it is not a specific indicator of ovulation. **Clinical Pearls for NEET-PG:** * **Best day to measure Progesterone:** Day 21 of a 28-day cycle (Mid-luteal phase). * **Most accurate sign of ovulation:** Ultrasound (disappearance of the dominant follicle). * **Basal Body Temperature (BBT):** Increases by 0.5–1.0°F after ovulation due to the thermogenic effect of progesterone. * **Endometrial Biopsy:** If done on day 21, "secretory changes" confirm the action of progesterone and thus ovulation.

Q: Primary oocyte remains arrested in the diplotene phase due to which of the following factors?

Oocyte maturation inhibitor. **Explanation:** **1. Why Option A is Correct:** During fetal life, primordial germ cells undergo mitosis to become oogonia, which then enter the first meiotic division to become **primary oocytes**. However, these oocytes do not complete meiosis I; they remain arrested in the **Prophase of Meiosis I (specifically the Diplotene stage)** until puberty. This arrest is primarily maintained by **Oocyte Maturation Inhibitor (OMI)**. OMI is a substance secreted by the surrounding **granulosa cells**. It acts by maintaining high levels of cyclic AMP (cAMP) within the oocyte, which prevents the activation of Maturation Promoting Factor (MPF), thereby keeping the oocyte in a state of meiotic dormancy. **2. Why Other Options are Incorrect:** * **Option B (Oocyte maturation stimulator):** This is a functional opposite. The "stimulator" for resuming meiosis is the **LH surge** during the menstrual cycle, which overcomes the inhibitory effect of OMI. * **Option C (Acetylcholine):** This is a neurotransmitter involved in the parasympathetic nervous system and muscle contraction; it has no established role in the meiotic arrest of oocytes. * **Option D (Estrogen):** While estrogen is vital for follicular development and the LH surge, it is not the direct biochemical factor responsible for the arrest in the diplotene stage. **3. High-Yield Clinical Pearls for NEET-PG:** * **Two Arrests:** Remember the "Two Meiotic Arrests": 1. **First Arrest:** Prophase I (Diplotene stage) – occurs before birth; ends at puberty (due to OMI). 2. **Second Arrest:** Metaphase II – occurs at ovulation; ends only if **fertilization** occurs. * **Dictyotene:** The prolonged diplotene stage in oogenesis is specifically referred to as the *dictyate* or *dictyotene* stage. * **The Trigger:** The resumption of Meiosis I is triggered by the **Pre-ovulatory LH surge**.

Q: During which period is vaginal pH most acidic?

Pregnancy. **Explanation:** The acidity of the vaginal environment is primarily determined by the presence of **Lactobacillus (Döderlein’s bacilli)**, which convert glycogen into lactic acid. **Why Pregnancy is the Correct Answer:** During pregnancy, there is a massive surge in **estrogen** levels. Estrogen increases the deposition of **glycogen** in the vaginal epithelial cells. This abundance of substrate allows Lactobacilli to produce high amounts of lactic acid, dropping the vaginal pH to its most acidic levels (typically between **3.5 and 4.5**). This acidic environment serves as a protective mechanism against ascending infections during gestation. **Analysis of Incorrect Options:** * **Menstruation:** The presence of blood (which is alkaline) and the shedding of the functional layer of the epithelium raise the pH toward neutrality or alkalinity (approx. 7.0). * **Puerperium:** Following delivery, estrogen levels drop sharply, and the presence of lochia (alkaline discharge) keeps the vaginal pH high, making the area more susceptible to infection. * **Newborn Period:** While a newborn has temporary acidity due to maternal estrogens, this effect fades quickly. Throughout childhood (pre-puberty), the vaginal pH remains neutral or alkaline (around 7.0) due to low estrogen and lack of glycogen. **High-Yield NEET-PG Pearls:** * **Estrogen = Glycogen = Acidity:** The vaginal pH is acidic only during periods of high estrogen (puberty to menopause, and peak during pregnancy). * **Progesterone** tends to decrease the glycogen content, slightly counteracting the estrogenic effect, but the net effect in pregnancy remains highly acidic. * **Clinical Correlation:** A rise in vaginal pH (>4.5) is a diagnostic hallmark for **Bacterial Vaginosis** and **Trichomoniasis**, whereas the pH remains normal (<4.5) in **Vulvovaginal Candidiasis**.

Question 1

Ovulation can be diagnosed by all except:

Accepted Answer

Measuring day 14 serum progesterone

Answer

Rise in basal body temperature in the second half of cycle

Answer

Study of cervical mucus

Answer

Endometrial histology

Question 2

Normal testicular development requires which of the following?

Accepted Answer

Y chromosome

Answer

XY chromosomes

Answer

XX chromosomes

Answer

X chromosome

Question 3

During ejaculation, from which of the following structures are sperms released from their storage?

Accepted Answer

Epididymis

Answer

Vas deferens

Answer

Rete testes

Answer

Seminal vesicle

Question 4

Estrogen is secreted by which cells?

Accepted Answer

Granulosa cells

Answer

Theca luteal cells

Answer

Theca interna cells

Answer

Theca externa cells

Question 5

The breast is a hormonally responsive organ. Which statement about progesterone is NOT true?

Accepted Answer

Progesterone promotes growth of both the stroma and the duct system of the breast

Answer

Progesterone is produced in the ovary

Answer

Progesterone stimulates growth of the lobules and the acini

Answer

Progesterone causes an increase in interstitial fluid in the breast

Question 6

A baby is born with a penis, a scrotum with no testes, no vagina, and XX chromosomes. What could cause this abnormality?

Accepted Answer

The presence of a testosterone-secreting tumor in the mother's right adrenal gland

Answer

Abnormally high levels of human chorionic gonadotropin (HCG) production by the trophoblast cells

Answer

Abnormally high levels of LH in the maternal blood

Answer

Abnormally low levels of testosterone in the maternal blood

Question 7

The laboratory report shows values of gonadotropin and ovarian hormones from a blood sample taken on day 20 of the menstrual cycle of a young woman. Whether her cycle was ovulatory or not may be validly assessed by the reported serum level of:

Accepted Answer

Progesterone

Answer

FSH

Answer

LH

Answer

Oestradiol

Question 8

Serum levels of different hormones estimated on the day of ovulation will depict which of the following?

Accepted Answer

FSH, LH, Estrogen and Progesterone

Question 9

Primary oocyte remains arrested in the diplotene phase due to which of the following factors?

Accepted Answer

Oocyte maturation inhibitor

Answer

Oocyte maturation stimulator

Answer

Acetylcholine

Answer

Estrogen

Question 10

During which period is vaginal pH most acidic?

Accepted Answer

Pregnancy

Answer

Menstruation

Answer

Puerperium

Answer

Newborn period

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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