Reproductive Physiology Practice Questions

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: What is the average progressive velocity of human sperm under standard laboratory conditions?

1-3 mm/min. ***1-3 mm/min*** - The typical average progressive velocity of human sperm, categorized as **Grade A (rapid progressive)** motility, ranges from **25 micrometers/second or faster**, which translates to approximately 1-3 mm/minute. - This velocity is crucial for sperm to traverse the female reproductive tract and reach the ovum for fertilization. *4-6 mm/min* - This velocity range is significantly faster than the **average progressive velocity** observed in viable human sperm under standard laboratory conditions. - While some individual sperm may achieve higher speeds, this range is not representative of the **average progressive motility** of a healthy sperm population. *6-9 mm/min* - This progressive velocity is exceptionally high and not typically observed as the average for human sperm, even for highly motile sperm. - Such a high velocity would indicate an **abnormally fast movement** not compatible with biological norms for average progressive motility. *10-13 mm/min* - This range represents an extremely rapid progressive velocity for human sperm, well beyond physiological averages. - It does not align with the standard measurements for **progressive motility**, which are generally much lower.

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.

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: Which of the following hormones is primarily secreted by Leydig cells?

Testosterone. ***Testosterone*** - **Leydig cells** (interstitial cells of Leydig), located adjacent to the **seminiferous tubules** in the testes, are the primary site of **testosterone synthesis** and secretion in males. - **Luteinizing hormone (LH)** from the pituitary gland stimulates these cells to produce testosterone. *DHT* - **Dihydrotestosterone (DHT)** is a more potent androgen than testosterone, but it is primarily formed from the peripheral conversion of testosterone by the enzyme **5-alpha-reductase** in target tissues (e.g., prostate, hair follicles), not directly secreted by Leydig cells in large amounts. - While testosterone is a precursor, DHT itself is not the primary hormone secreted by Leydig cells. *DHEA* - **Dehydroepiandrosterone (DHEA)** is an androgen primarily produced by the **adrenal glands**. - Although it can be a precursor to other sex hormones, it is not significantly produced or secreted by Leydig cells. *All of the options* - This option is incorrect because only **testosterone** is primarily secreted by Leydig cells. - DHT and DHEA are either primarily peripherally converted (DHT) or produced by different endocrine glands (DHEA).

Q: Sertoli cells in males secrete?

MIH. ***MIH (Müllerian Inhibiting Hormone)*** - **Sertoli cells** secrete multiple important substances, but among the given options, **Müllerian Inhibiting Hormone (MIH)**, also known as Anti-Müllerian Hormone (AMH), is the correct answer. - MIH causes the **regression of the Müllerian ducts** in male fetuses, preventing the development of female internal reproductive organs during sexual differentiation. - **Note:** Sertoli cells also secrete other important substances like **Inhibin** (negative feedback on FSH) and **Androgen Binding Protein (ABP)** (concentrates testosterone), but these are not among the options. *Testosterone* - **Testosterone** is primarily produced by the **Leydig cells** (interstitial cells) in the testes, not Sertoli cells. - While essential for male sexual development, spermatogenesis, and secondary sex characteristics, it is an **androgen** secreted by Leydig cells in response to LH stimulation. *Dehydroepiandrosterone* - **Dehydroepiandrosterone (DHEA)** is an **androgen precursor** primarily secreted by the **adrenal cortex** (zona reticularis). - It is not a secretory product of Sertoli cells in the testes. *Progesterone* - **Progesterone** is a **steroid hormone** primarily associated with the female reproductive system, particularly secreted by the corpus luteum and placenta. - It is not secreted by Sertoli cells in males.

Q: Which of the following hormones in pregnancy is more associated with blood vessels and increased permeability?

Estrogen. ***Estrogen*** - **Estrogen** levels increase significantly during pregnancy and are known to cause **vasodilation** and increased vascular permeability. - This hormonal influence contributes to common pregnancy symptoms like **edema**, increased blood flow to various organs, and changes in vascular tone. - Estrogen is the primary hormone responsible for systemic vascular changes during pregnancy. *Prolactin* - **Prolactin** is primarily responsible for **milk production** (lactation) and breast development during pregnancy. - While it has various metabolic effects, it is not directly associated with increased vascular permeability in the way estrogen is during pregnancy. *Relaxin* - **Relaxin** is a pregnancy hormone that does affect blood vessels and connective tissue remodeling. - However, its primary vascular effects are on **increasing vascular compliance** and **remodeling of maternal tissues** to accommodate pregnancy, rather than directly increasing permeability. - While relaxin contributes to hemodynamic changes, estrogen has a more direct and prominent role in increasing vascular permeability. *Progesterone* - **Progesterone** is crucial for maintaining pregnancy, relaxing smooth muscles, and supporting the uterine lining. - While it can affect vascular tone and causes some vasodilation, its primary role is not to directly increase blood vessel permeability to the same extent as estrogen.

Q: In the transition from a Graafian follicle to a functional corpus luteum, which of the following cellular events occurs?

Granulosa cells begin to express LH receptors. ***Granulosa cells begin to express LH receptors*** - During the late follicular phase, under **FSH** stimulation, **granulosa cells** in the developing Graafian follicle acquire **LH receptors**. - This acquisition of LH receptors is essential for the transition to a corpus luteum, as it enables the **LH surge** to trigger ovulation and subsequently stimulate **luteinization** and **progesterone production** by the corpus luteum. - While the initial expression occurs before ovulation, the functional significance becomes apparent during the transformation to the corpus luteum, making this the most critical receptor-related event in this transition among the given options. *Granulosa cells begin to express estrogen receptors* - Granulosa cells already express **estrogen receptors** in early follicular stages, which are essential for their proliferation and **aromatase synthesis**. - Estrogen receptor expression is characteristic of developing follicles throughout folliculogenesis, not specifically associated with corpus luteum formation. *Theca cells begin to express androgen receptors* - **Theca cells** produce **androgen precursors** (androstenedione, testosterone) under LH stimulation during the follicular phase, which granulosa cells convert to estrogen. - While theca cells contribute to the corpus luteum (theca-lutein cells), androgen receptor expression is not the primary defining cellular event of this transition. *Granulosa cells begin to express progesterone receptors* - The corpus luteum is the major source of **progesterone** in the luteal phase, but granulosa cells do not significantly upregulate progesterone receptors as part of their luteinization. - The key functional change is the cells' ability to *produce* large amounts of progesterone in response to LH, not increased progesterone receptor expression.

Q: Pubarche is due to?

Adrenal androgens. ***Adrenal androgens*** - **Pubarche**, the first appearance of **pubic hair**, is primarily caused by **adrenal androgens** (DHEA, DHEA-S, and androstenedione). - This process is linked to **adrenarche**, the maturation of the adrenal zona reticularis, which occurs in **both males and females** typically between ages 8-13. - Adrenal androgens are the **initial and primary stimulus** for pubic hair development in both sexes, occurring before gonadal sex hormone production increases significantly. - The increase in adrenal androgens is responsible for the development of pubic and axillary hair as the first visible sign of puberty. *Testosterone* - **Testosterone** from the testes (in males) or ovaries (in females) increases later during **gonadarche** and enhances pubic hair growth. - However, testosterone is **not the primary cause** of pubarche; it augments hair growth that was initiated by adrenal androgens. - Pubarche typically precedes the major rise in gonadal sex hormones. *Progesterone* - **Progesterone** is primarily involved in the menstrual cycle, pregnancy maintenance, and endometrial preparation. - It has **no direct role** in stimulating pubic hair development. *Estrogen* - **Estrogen** is responsible for female secondary sexual characteristics like breast development (thelarche), but does not stimulate pubic hair growth. - Pubic hair development is an **androgen-dependent** process, not estrogen-dependent.

Question 1

What does colostrum have compared to normal milk?

Accepted Answer

Increased proteins

Answer

Decreased potassium

Answer

Decreased sodium

Answer

Decreased calories

Question 2

What is the average progressive velocity of human sperm under standard laboratory conditions?

Accepted Answer

1-3 mm/min

Answer

4-6 mm/min

Answer

6-9 mm/min

Answer

10-13 mm/min

Question 3

Prostaglandins (PGs) in semen are secreted by?

Accepted Answer

Seminal vesicle

Answer

Prostate

Answer

Sperms

Answer

Testes

Question 4

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 5

Which of the following hormones is primarily secreted by Leydig cells?

Accepted Answer

Testosterone

Answer

DHT

Answer

DHEA

Answer

All of the options

Question 6

Sertoli cells in males secrete?

Accepted Answer

MIH

Answer

Testosterone

Answer

Dehydroepiandrosterone

Answer

Progesterone

Question 7

Which of the following hormones in pregnancy is more associated with blood vessels and increased permeability?

Accepted Answer

Estrogen

Answer

Prolactin

Answer

Relaxin

Answer

Progesterone

Question 8

In the transition from a Graafian follicle to a functional corpus luteum, which of the following cellular events occurs?

Accepted Answer

Granulosa cells begin to express LH receptors

Answer

Granulosa cells begin to express estrogen receptors

Answer

Theca cells begin to express androgen receptors

Answer

Granulosa cells begin to express progesterone receptors

Question 9

Pubarche is due to?

Accepted Answer

Adrenal androgens

Answer

Progesterone

Answer

Testosterone

Answer

Estrogen

Question 10

What is the primary reason puberty typically does not occur before the age of 8 years?

Accepted Answer

The hypothalamus does not secrete GnRH in a pulsatile manner

Answer

Inadequate synthesis of gonadotropins by the pituitary

Answer

Gonads are unresponsive to gonadotropin

Answer

Positive feedback action of gonadal steroids on pituitary

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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