Reproductive Physiology Practice Questions

Q: At the time point indicated by the arrow, the hormone levels are:

Increased estrogen, decreased progesterone. ***Increased estrogen, decreased progesterone*** - The arrow (red circle) points to Day 14, marking the approximate time of **ovulation**. At this point, the graph shows that **estrogen levels peak** just before ovulation and begin to decrease during ovulation. - Progesterone levels are relatively **low** during the follicular phase and only start to significantly increase **after ovulation** as the corpus luteum forms. *Decreased estrogen, increased progesterone* - This hormonal profile is characteristic of the **mid to late luteal phase**, not ovulation. - During the luteal phase, post-ovulation, the **corpus luteum** predominantly produces **progesterone**, leading to its increase, while estrogen levels decline from their pre-ovulatory peak. *Increased estrogen, increased progesterone* - While estrogen is high just before ovulation, **progesterone remains low** until after ovulation. - An increase in both significant progesterone and estrogen would be more indicative of the middle of the **luteal phase** when the corpus luteum is fully functional and producing both hormones in higher amounts. *Decreased estrogen, decreased progesterone* - This hormone profile typically occurs at the **very end of the luteal phase** if pregnancy does not occur, leading to the breakdown of the corpus luteum and subsequent menstruation. - It also characterizes the early follicular phase, not the time around ovulation.

Q: Testis is not the source for which of the following?

Dehydroepiandrosterone. ***Correct: Dehydroepiandrosterone (DHEA)*** - **DHEA is primarily produced by the adrenal glands**, specifically the zona reticularis of the adrenal cortex - It is an important **adrenal androgen** that serves as a precursor for sex hormones - The **testes are NOT a significant source** of DHEA production or secretion - This makes DHEA the correct answer to what the testis does NOT produce *Incorrect: Dihydrotestosterone (DHT)* - While most DHT in the body is formed by **peripheral conversion** of testosterone via 5-alpha-reductase in target tissues (prostate, skin, hair follicles) - The **testes do produce small amounts of DHT directly** from testosterone - Therefore, the testes ARE a source of DHT, making this option incorrect *Incorrect: Testosterone* - The testes are the **primary site of testosterone production** in males - **Leydig cells** synthesize and secrete testosterone in response to luteinizing hormone (LH) - Testosterone is essential for male sexual development, spermatogenesis, and secondary sexual characteristics *Incorrect: Androstenedione* - **Androstenedione is produced in the testes** as an intermediate in steroidogenesis - It serves as a precursor for both testosterone and estrogens - Also produced in adrenal glands and ovaries, but the testes ARE a definite source

Q: Sertoli cells secrete ?

Inhibin. ***Inhibin*** - **Sertoli cells** secrete **inhibin**, a hormone that selectively inhibits the secretion of **FSH** from the anterior pituitary. - Inhibin plays a crucial role in the **negative feedback loop** regulating spermatogenesis. *Androgen* - **Leydig cells**, not Sertoli cells, are responsible for producing and secreting **androgens**, primarily testosterone. - Androgens are essential for the development of male secondary sexual characteristics and spermatogenesis. *FSH* - **FSH** (Follicle-Stimulating Hormone) is secreted by the **anterior pituitary gland**, not by Sertoli cells. - FSH acts on Sertoli cells to stimulate spermatogenesis. *Testosterone* - **Testosterone** is the primary androgen produced by the **Leydig cells** in the testes. - Sertoli cells respond to testosterone, but they do not secrete it; instead, they convert some of it to estrogen and dihydrotestosterone.

Q: A major function of the epididymis is:

Storage and transport of mature sperm. ***Storage and transport of mature sperm*** - The epididymis is a highly convoluted tubule where **sperm mature** and gain motility over several weeks. - It also serves as a **storage site** for these mature sperm until ejaculation. *Secretion of estrogens* - **Estrogens** are primarily produced by the **ovaries** in females and, to a lesser extent, by the adrenal glands and testes. - The epididymis does not have a significant role in estrogen secretion. *Initiating the development of spermatozoa* - The initiation and primary development of spermatozoa, known as **spermatogenesis**, occurs in the **seminiferous tubules** of the testes. - The epididymis is responsible for further maturation and storage, not initial development. *Production of inhibin* - **Inhibin** is a hormone primarily produced by the **Sertoli cells** in the seminiferous tubules of the testes. - Its main function is to selectively inhibit the secretion of **follicle-stimulating hormone (FSH)** from the anterior pituitary.

Q: Spermatogenesis occurs at which temperature condition?

Temperature lower than core body temperature. ***Temperature lower than core body temperature*** - Spermatogenesis, the process of sperm production, is **temperature-sensitive** and requires a cooler environment than the core body temperature. - The **scrotum** is located outside the abdominal cavity, providing a temperature that is typically 2-3°C lower than the core body temperature, which is optimal for sperm development. *Temperature does not play a role* - This statement is incorrect as temperature plays a crucial role in spermatogenesis; **elevated temperatures can impair sperm production** and function. - Testicular function, including germ cell development, is highly sensitive to heat stress. *Temperature higher than core body temperature* - A temperature higher than core body temperature would be **detrimental to spermatogenesis**, leading to reduced sperm viability and quantity. - Exposure to high temperatures, such as through cryptorchidism (undescended testes), can cause **infertility**. *Body temperature* - If spermatogenesis were to occur at core body temperature, the quality and quantity of sperm would be **significantly reduced**, potentially leading to infertility. - The evolutionary advantage of the testes being located in the scrotum is precisely to maintain this **optimal cooler temperature**.

Q: Which of the following is not secreted by Sertoli cells?

Relaxin. ***Relaxin*** - **Sertoli cells** do not secrete relaxin; it is primarily produced in the **corpus luteum** during pregnancy to relax the pelvic ligaments and cervix. - In males, a small amount of relaxin is produced by the **prostate gland**, contributing to sperm motility. *Inhibin* - **Sertoli cells** secrete inhibin, which negatively regulates **FSH** secretion from the anterior pituitary, providing feedback control for spermatogenesis. - **Inhibin** acts to suppress the synthesis and release of **FSH** in the pituitary gland. *Follistatin* - **Sertoli cells** secrete follistatin, a protein that binds to and inhibits the activity of **activin**, and to a lesser extent, activin-like proteins such as **BMPs**. - Its main role is to regulate the bioavailability and signaling of members of the **TGF-β superfamily**. *Activin* - **Sertoli cells** secrete activin, which generally stimulates **FSH** secretion and *spermatogenesis*, acting in opposition to inhibin. - **Activin** is a dimer composed of two β subunits and has various roles in reproduction, immunology, and inflammation.

Q: Order of development of secondary sexual characteristic in male –

Testicular development–pubic hair–axillary hair–beard. ***Testicular development–pubic hair–axillary hair–beard*** - The first sign of puberty in males is typically an increase in **testicular size**, followed by the appearance of **pubic hair**. - **Axillary hair** usually develops after pubic hair, and the development of a **beard** or facial hair is one of the later secondary sexual characteristics. *Testicular development –beard–pubic hair–axillary hair* - This order incorrectly places **beard growth** and **axillary hair** before **pubic hair**, which is typically the second sign of male puberty. - While testicular development is indeed first, the subsequent sequence of hair development is incorrect. *Axillary hair–beard –pubic hair–testicular development* - This order is incorrect because **testicular development** is the initial event of male puberty, not a later one. - Additionally, both **axillary hair** and **beard growth** typically follow pubic hair development, not precede it. *Pubic hair–testicular development–axillary hair – beard* - This order incorrectly places **pubic hair** development before **testicular development**, which is the primary and earliest sign of puberty in males. - While the sequence of other hair development is later, the initial stage is incorrect.

Q: Levels of which of the following hormones are increased in postmenopausal women:

FSH. ***FSH*** - In postmenopausal women, the **ovaries cease to produce estrogen and progesterone**, leading to a loss of negative feedback on the hypothalamus and pituitary gland. - This results in a **significant increase in the secretion of Follicle-Stimulating Hormone (FSH)** and Luteinizing Hormone (LH) from the anterior pituitary as the body attempts to stimulate ovarian function. *Estrogen* - Estrogen levels **decrease significantly** during menopause as the ovaries stop producing ovarian follicles and ultimately cease ovulation. - The drop in estrogen is responsible for many menopausal symptoms, such as **hot flashes and vaginal dryness**. *Progesterone* - Progesterone levels also **decrease substantially** after menopause, as its primary source is the corpus luteum formed after ovulation, which no longer occurs. - The decline in progesterone contributes to the **irregular menstrual cycles** leading up to and during menopause. *Cortisol* - **Cortisol levels are not directly affected by menopause** in the same dramatic way as sex hormones. - Cortisol is a stress hormone produced by the adrenal glands, and its levels are primarily regulated by the **hypothalamic-pituitary-adrenal (HPA) axis**, which is distinct from the reproductive axis.

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

Spermiogenesis. ***Spermiogenesis*** - **Sertoli cells** are crucial for supporting and nourishing developing **spermatids** during their maturation into spermatozoa, a process known as spermiogenesis. - They form the **blood-testis barrier**, which protects germ cells from immune attack and provides a unique microenvironment necessary for this process. *Gonadogenesis* - **Gonadogenesis** is the formation and development of the gonads (testes or ovaries). While Sertoli cells differentiate during male gonadogenesis, they are not the primary drivers of this broader developmental process. - This process involves the differentiation of primordial germ cells and somatic cells, influenced by various genetic and hormonal factors. *Secretion of seminal fluid* - **Seminal fluid** is primarily secreted by accessory glands such as the **seminal vesicles**, **prostate gland**, and **bulbourethral glands**. - Sertoli cells do not directly contribute to the bulk of seminal fluid, although they secrete a fluid component within the seminiferous tubules. *Testosterone secretion* - **Testosterone** is primarily secreted by the **Leydig cells** (also known as interstitial cells of Leydig), which are located in the connective tissue between the seminiferous tubules. - While Sertoli cells produce **androgen-binding protein** that helps maintain high local testosterone concentrations, they do not synthesize testosterone themselves.

Q: Which hormone binds to the receptors on Leydig cells?

LH. ***LH*** - **Luteinizing Hormone (LH)** binds to specific receptors on **Leydig cells** in the testes. - This binding stimulates the Leydig cells to produce and secrete **testosterone**, which is crucial for male reproductive function. *TSH* - **Thyroid-Stimulating Hormone (TSH)** acts on the **thyroid gland** to stimulate the production of thyroid hormones (T3 and T4). - It does not have a direct role in regulating Leydig cell function. *GH* - **Growth Hormone (GH)** primarily promotes **tissue growth** and development by stimulating protein synthesis and cell proliferation throughout the body. - While it has broad effects, it does not directly bind to Leydig cell receptors for testosterone production. *PRL* - **Prolactin (PRL)** is primarily involved in **lactation** in females and has various general metabolic effects in both sexes. - While it plays a role in male reproductive health, it does not directly stimulate Leydig cells via specific receptors to produce testosterone.

Question 1

At the time point indicated by the arrow, the hormone levels are:

Accepted Answer

Increased estrogen, decreased progesterone

Answer

Decreased estrogen, increased progesterone

Answer

Increased estrogen, increased progesterone

Answer

Decreased estrogen, decreased progesterone

Question 2

Testis is not the source for which of the following?

Accepted Answer

Dehydroepiandrosterone

Answer

Testosterone

Answer

Dihydrotestosterone

Answer

Androstenodione

Question 3

Sertoli cells secrete ?

Accepted Answer

Inhibin

Answer

Androgen

Answer

FSH

Answer

Testosterone

Question 4

A major function of the epididymis is:

Accepted Answer

Storage and transport of mature sperm

Answer

Secretion of estrogens

Answer

Initiating the development of spermatozoa

Answer

Production of inhibin

Question 5

Spermatogenesis occurs at which temperature condition?

Accepted Answer

Temperature lower than core body temperature

Answer

Temperature does not play a role

Answer

Temperature higher than core body temperature

Answer

Body temperature

Question 6

Which of the following is not secreted by Sertoli cells?

Accepted Answer

Relaxin

Answer

Inhibin

Answer

Follistatin

Answer

Activin

Question 7

Order of development of secondary sexual characteristic in male –

Accepted Answer

Testicular development–pubic hair–axillary hair–beard

Answer

Testicular development –beard–pubic hair–axillary hair

Answer

Axillary hair–beard –pubic hair–testicular development

Answer

Pubic hair–testicular development–axillary hair – beard

Question 8

Levels of which of the following hormones are increased in postmenopausal women:

Accepted Answer

FSH

Answer

Estrogen

Answer

Progesterone

Answer

Cortisol

Question 9

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

Accepted Answer

Spermiogenesis

Answer

Gonadogenesis

Answer

Secretion of seminal fluid

Answer

Testosterone secretion

Question 10

Which hormone binds to the receptors on Leydig cells?

Accepted Answer

LH

Answer

TSH

Answer

GH

Answer

PRL

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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