Reproductive Physiology Practice Questions

Q: What is the primary gene responsible for gonads to testes differentiation?

SRY gene. ***SRY gene*** - The **SRY gene** (Sex-determining Region Y) is located on the **Y chromosome** and is the **primary master regulator** that initiates the cascade of events leading to testicular development from the undifferentiated bipotential gonad. - Its gene product, the **SRY protein**, acts as a transcription factor that directly upregulates downstream genes like **SOX9**, triggering male sex determination. *WNT-4 gene* - The **WNT-4 gene** is primarily involved in **female sex differentiation**, promoting ovarian development and actively suppressing male differentiation pathways. - Its expression is downregulated in males during gonad development, allowing testicular differentiation to proceed. *DAX1 gene* - The **DAX1 gene** (Dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on chromosome X, gene 1) is a negative regulator of male sexual differentiation. - In females, it contributes to ovarian development; overexpression in males can lead to **sex reversal** and gonadal dysgenesis. *SOX9 gene* - While **SOX9** is critical for testicular differentiation, it acts **downstream** of SRY and is not the primary initiator. - SRY activates SOX9, which then maintains testicular development through positive feedback loops and regulation of anti-Müllerian hormone (AMH).

Q: Ovulation occurs how long after the LH surge peak?

12-24 hours. ***12-24 hours*** - Ovulation, the release of a mature egg from the **ovary**, typically occurs within **12 to 24 hours after the peak of the luteinizing hormone (LH) surge**. - The LH surge itself usually lasts 24 to 48 hours and is a critical signal for the final maturation and release of the oocyte. *24-48 hours* - While the **LH surge** can last up to 48 hours, **ovulation** (the actual release of the egg) generally happens more rapidly, usually within 12-24 hours of the *peak* of this surge. - This timeframe is a common misconception, as it refers more to the duration of the surge rather than the precise timing of ovulation post-peak. *48-72 hours* - Ovulation rarely occurs this late after the peak of the **LH surge**; if it does, it suggests a potential delay or irregularity in the **ovulatory process**. - The window for successful fertilization is relatively narrow and aligns with the more immediate post-surge timing. *72-96 hours* - This time frame is significantly beyond the typical window for **ovulation** following the **LH surge**. - By this point, the egg would have either been released or the ovulatory event would have passed without the egg releasing.

Q: LH surge is associated with?

Increased estrogen & decreased progesterone. ***Increased estrogen & decreased progesterone*** - The **LH surge** is triggered by a significant rise in **estrogen** levels from the dominant follicle, indicating ovarian readiness. - At the time of the LH surge, **progesterone** levels remain low; they only begin to rise significantly after ovulation, when the corpus luteum forms. *Increased estrogen & increased progesterone* - While **estrogen** levels are high, **progesterone** only significantly increases *after* ovulation, as the corpus luteum develops. - High estrogen *and* high progesterone together are typically seen in the **luteal phase**, not at the peak of the LH surge. *Decreased estrogen & increased progesterone* - A decrease in **estrogen** would suppress LH, not trigger a surge. - Increased **progesterone** would also inhibit LH release via negative feedback in the follicular phase if it were to occur pre-ovulation. *Decreased estrogen & decreased progesterone* - Both **decreased estrogen** and **decreased progesterone** would lead to low FSH/LH levels and would not promote an LH surge or ovulation. - This hormonal profile is more characteristic of the very early follicular phase or menopause.

Q: What is the primary hormone responsible for the secretion of milk?

Prolactin. ***Prolactin*** - **Prolactin** is the primary hormone synthesized and secreted by the pituitary gland that is responsible for **milk production** (lactogenesis) in the mammary glands after childbirth. - Its levels rise significantly during pregnancy and remain elevated with regular suckling, which stimulates its release and maintains milk supply. *Oxytocin* - **Oxytocin** is primarily responsible for the **milk ejection reflex** (let-down reflex), causing the contraction of myoepithelial cells around the alveoli to release milk. - It does not stimulate the production of milk itself but rather its expulsion from the breast. *Glucocorticoids* - **Glucocorticoids** (like cortisol) play a role in mammary gland development and maturation, and can have permissive effects on prolactin's action. - However, they are not the primary hormone directly responsible for stimulating milk secretion. *Relaxin* - **Relaxin** is a hormone primarily involved in relaxing ligaments in the pelvis and softening the cervix during childbirth. - It has no direct primary role in the production or secretion of breast milk.

Q: After injecting testosterone in a hypoandrogenic male, which of the following occurs ?

Decreased FSH secretion. ***Decreased FSH secretion*** - Exogenous testosterone administration causes **negative feedback** on the hypothalamic-pituitary-gonadal axis, suppressing **GnRH** release and consequently decreasing both **LH** and **FSH** secretion. - The **FSH suppression** is clinically significant as it leads to impaired **spermatogenesis** and **Sertoli cell function**, which is a major concern in testosterone replacement therapy. *Increased spermatogenesis* - This is **incorrect** - exogenous testosterone actually **suppresses spermatogenesis** despite high systemic testosterone levels. - The suppression occurs due to decreased **FSH** and reduced **intratesticular testosterone** concentrations, which cannot be replaced by systemic testosterone alone. *None of the options* - This is **incorrect** because exogenous testosterone administration has well-established effects on the **hypothalamic-pituitary-gonadal axis**. - Multiple hormonal changes occur, including suppression of both **gonadotropins** (LH and FSH) through proven **negative feedback mechanisms**. *Increased LH secretion* - This is **incorrect** - exogenous testosterone actually **decreases LH secretion** through negative feedback at the hypothalamic-pituitary level. - **High circulating testosterone** suppresses **GnRH** release, leading to reduced **LH** production, not increased secretion.

Q: In the breast, lactiferous ducts are formed under the influence of which hormone?

Estrogen. ***Estrogen*** - **Estrogen** plays a primary role in the development and branching of the **lactiferous ducts** in the breast. - It stimulates the proliferation of ductal epithelial cells, contributing to the growth of the duct system. *Progesterone* - **Progesterone** is primarily responsible for the development of the **lobuloalveolar system** and secretory differentiation within the breast. - While essential for lactation, its main function is not duct formation but rather the maturation of secretory units. *LH* - **Luteinizing hormone (LH)** is crucial for ovulation and the formation of the **corpus luteum** in the ovaries. - It has no direct role in the structural development of the lactiferous ducts in the breast. *FSH* - **Follicle-stimulating hormone (FSH)** is essential for the growth and maturation of **ovarian follicles**. - It does not directly influence the formation or development of lactiferous ducts in the breast.

Q: Spermatogenesis takes place in?

Seminiferous tubule. ***Seminiferous tubule*** - **Spermatogenesis**, the process of sperm production, primarily occurs within the highly convoluted **seminiferous tubules** located in the testes. - These tubules contain **Sertoli cells** that support and nourish developing sperm, and **germ cells** that undergo meiosis to form spermatozoa. *Epididymis* - The **epididymis** is a coiled tube where sperm undergo maturation, gain motility, and are stored before ejaculation. - It is not the site of sperm production, but rather for **sperm maturation** and storage. *Ductus deferens* - The **ductus deferens** (vas deferens) is a muscular tube that transports mature sperm from the epididymis to the ejaculatory duct during ejaculation. - It is a **transport pathway** and does not play a role in sperm formation or maturation directly. *Prostate* - The **prostate gland** contributes fluids to the semen, particularly a milky fluid containing citrate (nutrient), enzymes, and prostate-specific antigen (PSA). - These fluids aid in sperm activation and motility but do not contribute to **sperm production**.

Q: What does spermiogenesis refer to?

Formation of spermatozoa from spermatids. ***Formation of spermatozoa from spermatids*** - **Spermiogenesis** is the final stage of spermatogenesis, involving the remarkable transformation of a round **spermatid** into a motile, mature **spermatozoon**. - This process includes crucial morphological changes such as the formation of the **acrosome**, condensation of the nucleus, development of the flagellum, and shedding of excess cytoplasm. *Formation of spermatozoa from spermatogonia* - This describes the entire process of **spermatogenesis**, which begins with **spermatogonia** and encompasses multiple stages including mitosis, meiosis, and spermiogenesis. - While it's the ultimate outcome, it doesn't specifically define the detailed transformation from spermatid to sperm. *Formation of spermatids from spermatocytes* - This stage refers to **meiosis II**, where **secondary spermatocytes** undergo division to produce **spermatids**. - Spermatids are precursors to spermatozoa and still require significant morphological changes to become mature sperm. *Formation of secondary spermatocytes from primary spermatocytes* - This describes **meiosis I**, where a **primary spermatocyte** divides to form two **secondary spermatocytes**. - This step reduces the chromosome number by half but doesn't involve the final morphological changes seen in spermiogenesis.

Q: Which hormone surge indicates the fertile period in females?

LH. ***LH*** - The **luteinizing hormone (LH) surge** triggers **ovulation**, releasing a mature egg from the follicle. - This surge is a key indicator of the **fertile window** in a woman's menstrual cycle. *FSH* - **Follicle-stimulating hormone (FSH)** primarily stimulates the growth and development of **ovarian follicles** early in the menstrual cycle, prior to the fertile period. - While essential for follicle maturation, it does not directly signal the immediate fertile window or ovulation. *Estrogen* - **Estrogen levels peak** just before the LH surge, playing a role in triggering the surge itself through positive feedback. - However, estrogen itself does not directly indicate the onset of the fertile period; rather, the subsequent LH surge does. *Oxytocin* - **Oxytocin** is largely involved in processes like **uterine contractions during childbirth** and **milk ejection during lactation**. - It has no direct role in indicating a female's fertile period or timing of ovulation.

Q: Decidual reaction is due to which hormone?

Progesterone. ***Progesterone*** - The **decidual reaction** is a specific uterine stromal cell differentiation process that prepares the endometrium for **implantation and pregnancy maintenance**. - This process is primarily induced and maintained by **progesterone**, which causes stromal cells to enlarge, accumulate glycogen and lipids, and secrete various factors essential for embryonic development. *Estrogen* - Estrogen plays a crucial role in the **proliferation of the endometrium** during the follicular phase, building up the uterine lining. - While estrogen is essential, it acts in conjunction with progesterone; progesterone is the **primary hormone** responsible for the decidualization process itself. *LH* - Luteinizing hormone (LH) is responsible for triggering **ovulation** and stimulating the corpus luteum to produce progesterone. - LH's direct role is not in the decidual reaction of the endometrium but rather in the **ovarian events** that lead to the production of the hormones that cause decidualization. *FSH* - Follicle-stimulating hormone (FSH) is vital for the growth and maturation of **ovarian follicles** and **estrogen production**. - FSH does not directly induce the decidual reaction but facilitates the production of estrogen, which then contributes to endometrial proliferation, a precursor to progesterone's decidualizing effect.

Question 1

What is the primary gene responsible for gonads to testes differentiation?

Accepted Answer

SRY gene

Answer

WNT-4 gene

Answer

DAX1 gene

Answer

SOX9 gene

Question 2

Ovulation occurs how long after the LH surge peak?

Accepted Answer

12-24 hours

Answer

48-72 hours

Answer

72-96 hours

Answer

24-48 hours

Question 3

LH surge is associated with?

Accepted Answer

Increased estrogen & decreased progesterone

Answer

Increased estrogen & increased progesterone

Answer

Decreased estrogen & increased progesterone

Answer

Decreased estrogen & decreased progesterone

Question 4

What is the primary hormone responsible for the secretion of milk?

Accepted Answer

Prolactin

Answer

Oxytocin

Answer

Glucocorticoids

Answer

Relaxin

Question 5

After injecting testosterone in a hypoandrogenic male, which of the following occurs ?

Accepted Answer

Decreased FSH secretion

Answer

Increased spermatogenesis

Answer

None of the options

Answer

Increased LH secretion

Question 6

In the breast, lactiferous ducts are formed under the influence of which hormone?

Accepted Answer

Estrogen

Answer

Progesterone

Answer

LH

Answer

FSH

Question 7

Spermatogenesis takes place in?

Accepted Answer

Seminiferous tubule

Answer

Epididymis

Answer

Ductus deferens

Answer

Prostate

Question 8

What does spermiogenesis refer to?

Accepted Answer

Formation of spermatozoa from spermatids

Answer

Formation of spermatozoa from spermatogonia

Answer

Formation of spermatids from spermatocytes

Answer

Formation of secondary spermatocytes from primary spermatocytes

Question 9

Which hormone surge indicates the fertile period in females?

Accepted Answer

LH

Answer

FSH

Answer

Estrogen

Answer

Oxytocin

Question 10

Decidual reaction is due to which hormone?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

LH

Answer

FSH

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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