Reproductive Physiology Practice Questions

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: 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: The primary oocyte remains arrested in which stage until ovulation?

Diplotene stage. ***Diplotene stage*** - The primary oocyte enters **meiosis I** during fetal development but arrests in the **prophase I substage of diplotene**. - This arrest is maintained until **puberty** and **ovulation**, when hormonal surges trigger the completion of meiosis I. *Pachytene stage* - The **pachytene stage** of prophase I is when **crossing over** (recombination) occurs between homologous chromosomes. - While an important step in meiosis, it precedes the **diplotene arrest** point. *Metaphase* - **Metaphase** is a stage where chromosomes align at the metaphase plate, either in meiosis I or meiosis II. - The primary oocyte's arrest occurs much earlier, during **prophase I**, not metaphase. *Telophase* - **Telophase** is the final stage of mitosis or meiosis where chromosomes decondense and nuclear envelopes reform. - The oocyte's initial arrest point is in **prophase I**, long before telophase.

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

Decreased FSH secretion. ***Decreased FSH secretion*** - Exogenous testosterone administration leads to **negative feedback** on the hypothalamic-pituitary-gonadal axis, suppressing **GnRH** release, which in turn decreases both **LH** and **FSH** secretion. - FSH suppression is particularly clinically significant because it results in **inhibition of spermatogenesis**, which is a key consideration when using testosterone replacement therapy. - The decrease in FSH, combined with reduced **intratesticular testosterone** (due to LH suppression), impairs Sertoli cell function and sperm production. *Decreased LH secretion* - **This also occurs** with exogenous testosterone administration due to negative feedback on the hypothalamus and pituitary. - Testosterone primarily suppresses **LH** through direct negative feedback at the hypothalamic-pituitary level. - However, in the context of this question focusing on the consequences in a hypoandrogenic male receiving testosterone, the **FSH suppression** and its impact on spermatogenesis is the more clinically emphasized outcome. - **Note:** Both LH and FSH decrease; this question likely emphasizes FSH due to its role in fertility concerns with testosterone therapy. *Increased spermatogenesis* - This is **incorrect**. Exogenous testosterone actually **suppresses spermatogenesis** through multiple mechanisms: - Decreased **FSH** (essential for Sertoli cell function) - Decreased **intratesticular testosterone** concentration (despite high systemic levels) - The high local testosterone concentration within the seminiferous tubules (30-100x serum levels) cannot be achieved by systemic testosterone alone. *None of the options* - This is incorrect because exogenous testosterone administration clearly causes **suppression of gonadotropins** (both LH and FSH) through well-established negative feedback mechanisms.

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: 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: What does colostrum have compared to normal milk?

Increased proteins. ***Increased proteins*** - **Colostrum** is rich in **immunoglobulins (antibodies)** like IgA, IgG, and IgM, which are proteins crucial for passive immunity in the newborn, making its protein content **2-3 times higher** than mature milk (approximately 2.3 g/100 mL vs 0.9 g/100 mL). - These high protein levels also include **lactoferrin** and **growth factors**, which support the development of the infant's gut and immune system. - This is the **most clinically significant** distinguishing feature of colostrum. *Decreased potassium* - **Potassium (K)** levels in colostrum are actually **similar to or slightly higher** than mature milk (approximately 74 mg/100 mL vs 51 mg/100 mL). - This option is incorrect as potassium is not decreased. *Decreased sodium* - **Sodium (Na)** levels are actually **significantly higher** in colostrum than in mature milk (approximately 48 mg/100 mL vs 15 mg/100 mL). - This elevated sodium gives colostrum a distinct salty taste, differentiating it from mature milk. - This option is incorrect as sodium is increased, not decreased. *Decreased calories* - While colostrum has a **lower fat content** than mature milk, leading to somewhat lower caloric density (54-58 kcal/100 mL vs 65-70 kcal/100 mL), this is not the primary distinguishing characteristic. - The most important feature of colostrum is its **high protein and immunoglobulin content** for immune protection, not its caloric value.

Q: According to some older studies, which sperm chromosome was hypothesized to be associated with faster initial motility?

Y chromosome. ***Y chromosome*** - **Older hypothesis** suggested that Y chromosome-bearing sperm might be faster due to being slightly smaller and lighter - However, **modern rigorous studies have largely debunked this theory** - The chromosomal size difference (X vs Y) represents less than 0.02% of total sperm mass, making any speed difference negligible - **Current scientific consensus**: No consistent, reproducible motility difference has been demonstrated *X chromosome* - X-bearing sperm are marginally larger due to more DNA content - Early theories suggested they were slower but more robust - **Modern evidence does not support consistent motility differences** between X and Y bearing sperm *Both same* - This actually reflects the **current scientific consensus** based on modern flow cytometry and separation studies - Most rigorous contemporary research shows no reliable motility differences between X and Y chromosome-bearing sperm - The Ericsson albumin method (based on speed separation) has been largely discredited *None of the options* - This option is incorrect as the question asks about historical hypotheses - Early studies did propose the Y chromosome theory, even though it's now considered largely inaccurate

Q: Prostaglandins (PGs) in semen are secreted by?

Seminal vesicle. ***Seminal vesicle*** - The **seminal vesicles** are the primary source of **prostaglandins (PGs)** in semen, contributing significantly to the seminal fluid volume. - These PGs play a crucial role in promoting **sperm motility** and facilitating fertilization. *Prostate* - The **prostate gland** primarily secretes **citrate**, **acid phosphatase**, and **prostate-specific antigen (PSA)**, which contribute to sperm activation and semen liquefaction. - It does not significantly contribute to the prostaglandin content of semen. *Sperms* - **Spermatozoa** themselves primarily contribute genetic material and are not a significant source of prostaglandin synthesis in semen. - Their main function is fertilization, not the production of accessory gland secretions. *Testes* - The **testes** are responsible for **spermatogenesis** (sperm production) and the synthesis of **androgens** like testosterone. - They do not secrete prostaglandins into the seminal fluid.

Question 1

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 2

Spermatogenesis takes place in?

Accepted Answer

Seminiferous tubule

Answer

Epididymis

Answer

Ductus deferens

Answer

Prostate

Question 3

The primary oocyte remains arrested in which stage until ovulation?

Accepted Answer

Diplotene stage

Answer

Pachytene stage

Answer

Metaphase

Answer

Telophase

Question 4

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 5

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

Accepted Answer

Decreased FSH secretion

Answer

Decreased LH secretion

Answer

Increased spermatogenesis

Answer

None of the options

Question 6

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

Accepted Answer

Prolactin

Answer

Oxytocin

Answer

Glucocorticoids

Answer

Relaxin

Question 7

Which hormone surge indicates the fertile period in females?

Accepted Answer

LH

Answer

FSH

Answer

Estrogen

Answer

Oxytocin

Question 8

What does colostrum have compared to normal milk?

Accepted Answer

Increased proteins

Answer

Decreased potassium

Answer

Decreased sodium

Answer

Decreased calories

Question 9

According to some older studies, which sperm chromosome was hypothesized to be associated with faster initial motility?

Accepted Answer

Y chromosome

Answer

None of the options

Answer

X chromosome

Answer

Both same

Question 10

Prostaglandins (PGs) in semen are secreted by?

Accepted Answer

Seminal vesicle

Answer

Prostate

Answer

Sperms

Answer

Testes

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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