Reproductive Physiology Practice Questions

Q: Sperm remain in the epididymis for ____ days?

12-14 days. ***12-14 days*** - Sperm typically spends **12-14 days** maturing and being stored in the epididymis. - This time allows for the acquisition of **motility** and **fertilizing capacity**. *25-30 days* - This duration is **too long** for the typical transit and storage time of sperm in the epididymis. - Extended retention might indicate an issue with **ejaculation** or sperm transport. *5-7 days* - This period is **too short** for sperm to fully mature and gain maximal fertilizing capacity within the epididymis. - Sperm would still be relatively immobile and **unfertile** at this point. *2-3 days* - This duration is significantly **too short** for the necessary maturation process to occur in the epididymis. - Sperm would have **very limited motility** and fertilizing ability.

Q: Which of the following is not seen in humans?

Estrous Cycle. ***Estrous Cycle*** - The **estrous cycle** is characteristic of most mammals, where females are sexually receptive only during a specific period called **estrus** or "heat." - This cycle typically involves the reabsorption of the **endometrium** if fertilization does not occur, rather than shedding. *Menstrual Cycle* - The **menstrual cycle** is the reproductive cycle found in humans and some other primates, characterized by the monthly shedding of the **endometrium** if pregnancy does not occur. - It involves hormonal fluctuations that prepare the uterus for potential pregnancy and results in **menstruation**. *Ovarian Cycle* - The **ovarian cycle** is a series of events in the human ovary that leads to the maturation of an **oocyte** and its release (ovulation), as well as the formation of the **corpus luteum**. - It is an integral part of the broader menstrual cycle in humans, influencing the **uterine changes**. *Endometrial cycle* - The **endometrial cycle** (or uterine cycle) refers to the cyclical changes occurring in the **endometrium** of the human uterus in response to hormonal fluctuations, primarily estrogen and progesterone. - These changes prepare the uterus for implantation of an **embryo** and culminate in menstruation if pregnancy does not occur.

Q: The major source of estrogen after menopause is?

Aromatization of androgens in adipose tissue. ***Aromatization of androgens in adipose tissue*** - After menopause, ovarian function declines significantly, reducing direct **estrogen production**. - **Adipose tissue** becomes the primary site for the conversion of adrenal androgens (like androstenedione) into estrogens, predominantly **estrone**, via the enzyme **aromatase**. *Aromatization of androgens in granulosa cells of the ovary* - **Granulosa cells** are the primary site of estrogen production in the **premenopausal ovary**, converting androgens from theca cells into estradiol. - After menopause, granulosa cell function and numbers decline significantly, ceasing their role as a major estrogen source. *Adrenal production of estrogens* - The **adrenal glands** primarily produce **androgens** (like DHEA and androstenedione) which are then converted to estrogens in peripheral tissues, especially after menopause. - They do not directly produce significant amounts of estrogen themselves. *Aromatization of androgens in theca cells of ovary* - **Theca cells** in the premenopausal ovary predominantly produce **androgens** (androstenedione and testosterone) under the influence of LH. - These androgens are then transported to granulosa cells for aromatization; theca cells themselves do not produce estrogen.

Q: How many hours does human sperm remain viable in the female genital tract?

72-96 hrs. ***72-96 hrs*** - Sperm can survive in the **female reproductive tract** for approximately **3-4 days (72-96 hours)**, which represents the typical maximum viability period. - This extended viability is due to the protective environment and **nutrient supply** within the female tract, particularly in the cervical crypts and fallopian tubes. - This duration represents the **commonly accepted range** for sperm viability in standard medical examinations and determines the fertile window for conception. *24-48 hrs* - While 24-48 hours represents a significant portion of sperm viability, many sperm can remain viable for longer periods, up to 3-4 days under optimal conditions. - This timeframe underestimates the full **fertile window** that contributes to successful fertilization potential. *12-24 hrs* - This period is generally considered the lifespan of the **ovum (egg)** after ovulation, not the sperm. - It significantly **underestimates** the actual survival time of sperm in the female reproductive tract. *6-8 hrs* - This duration is far too short for sperm viability in the female reproductive tract; sperm can survive much longer in the protective cervical and tubal environment. - Such a short window would severely limit the chances of **fertilization** and is not physiologically accurate.

Q: MIS is secreted by?

Sertoli cell. ***Sertoli cell*** - **Sertoli cells** in the testes secrete **Müllerian Inhibiting Substance (MIS)**, also known as anti-Müllerian hormone (AMH) - MIS causes **regression of Müllerian ducts** during male sexual differentiation, preventing development of female internal reproductive organs - Secretion begins around 8 weeks of fetal development and continues throughout life *Leydig cell* - **Leydig cells** produce **testosterone and other androgens** - While essential for masculinization and male sexual development, they do not secrete MIS - Located in the interstitial space between seminiferous tubules *Granulosa cells* - **Granulosa cells** are found in the **ovarian follicles** in females - They also produce AMH (anti-Müllerian hormone), but in the female reproductive context - In females, AMH regulates follicular development, not Müllerian duct regression *Theca cells* - **Theca cells** are also ovarian cells that produce **androgens** as precursors for estrogen synthesis - They work in conjunction with granulosa cells in the two-cell, two-gonadotropin model - They do not secrete MIS

Q: Puberty happens due to pulsatile release of -

GnRH. ***GnRH*** - Puberty is initiated by the pulsatile release of **Gonadotropin-Releasing Hormone (GnRH)** from the hypothalamus. - This pulsatile release primes the anterior pituitary to secrete gonadotropins, **Luteinizing Hormone (LH)** and **Follicle-Stimulating Hormone (FSH)**. *Testosterone* - **Testosterone** is a sex hormone whose release is stimulated by LH, but it is not the primary initiator of puberty. - Its levels rise later in puberty, driven by the pituitary-gonadal axis, causing the development of **secondary sexual characteristics** in males. *LH/ICSH* - **Luteinizing Hormone (LH)** and **Interstitial Cell-Stimulating Hormone (ICSH)** (the male equivalent of LH) are pituitary hormones whose release is stimulated by GnRH. - They act on the gonads to stimulate sex hormone production, but their release is a consequence, not the initial trigger, of the pulsatile activity related to puberty. *Estrogen* - **Estrogen** is a sex hormone primarily produced in females in response to FSH and LH. - Similar to testosterone, its elevated levels are a downstream effect of the hypothalamic-pituitary-gonadal axis activation during puberty, leading to the development of female secondary sexual characteristics.

Q: Mullerian inhibiting substance (MIS) is produced by:

Sertoli cells. ***Sertoli cells*** - **Sertoli cells** in the fetal testes produce **Müllerian inhibiting substance (MIS)**, also known as anti-Müllerian hormone (AMH). - **MIS** is crucial for the regression of the paramesonephric (Müllerian) ducts in male fetuses, preventing the development of female internal reproductive organs. *Stroma* - **Stromal cells** in the gonads provide structural support and a microenvironment for germ cell development but do not primarily produce MIS. - Their primary roles involve hormone synthesis and interaction with germ cells and somatic cells. *Germ cells* - **Germ cells** (spermatogonia or oocytes) are the precursors to sperm and eggs, responsible for genetic transmission. - They do not produce **Müllerian inhibiting substance (MIS)**; their role is focused on meiosis and reproduction. *Leydig cells* - **Leydig cells** in the testes produce **androgens**, primarily testosterone, which is essential for the development of male internal and external genitalia. - They do not produce **Müllerian inhibiting substance (MIS)**; their function is distinct from Müllerian duct regression.

Q: Motor protein responsible for sperm motility is -

Dynein. ***Dynein*** - **Dynein** is a motor protein that powers the movement of **cilia** and **flagella**, including the tail of sperm. - It generates the **sliding motion** between microtubules within the axoneme, leading to the characteristic whip-like movement of sperm. *Actin* - **Actin** is a major component of the cytoskeleton in many cells and is involved in cell shape, division, and muscle contraction. - While present in sperm, actin is not directly responsible for the **propulsive motility** of the flagellum. *Myosin* - **Myosin** is a motor protein primarily associated with **muscle contraction** and cellular transport along actin filaments. - It does not play a direct role in the **flagellar movement** of sperm. *Kinesin* - **Kinesin** is a motor protein that typically moves along **microtubules**, transporting vesicles and organelles, usually away from the cell body (anterograde transport). - It is not involved in the actual **motility mechanism** of sperm flagella.

Q: Which hormone has permissive role in puberty?

Leptin. ***Leptin*** - **Leptin** acts as a permissive signal that informs the hypothalamus about the body's **nutritional status** and energy reserves. - A certain threshold level of **leptin**, reflecting adequate body fat, is generally required for the initiation and progression of puberty. *GH* - **Growth hormone (GH)** is crucial for overall somatic growth during childhood and adolescence, but it does not directly trigger the onset of puberty. - While GH is important for the pubertal growth spurt, it acts primarily in an anabolic role rather than initiating the reproductive axis. *GnRH* - **Gonadotropin-releasing hormone (GnRH)** is the primary neurohormone that directly initiates and drives puberty by stimulating the pituitary. - However, GnRH is the *driver* of puberty rather than a *permissive* factor, meaning its pulsatile release is the direct trigger for the reproductive cascade. *Insulin* - **Insulin** is involved in glucose metabolism and energy homeostasis throughout the body. - While good metabolic health is indirectly important for puberty, insulin does not play a direct permissive role in initiating the pubertal process like leptin does.

Q: Maximum steroid produced by fetal adrenal:

DHEA-S. ***DHEA-S*** - The fetal adrenal gland, particularly the **fetal zone**, is highly developed and specialized in producing large amounts of **dehydroepiandrosterone sulfate (DHEA-S)**. - DHEA-S serves as a crucial precursor for **estrogen synthesis** in the placenta during pregnancy. *Progesterone* - While essential for maintaining pregnancy, **progesterone** is primarily produced by the **placenta**, not the fetal adrenal gland. - The fetal adrenal gland lacks the enzyme **3β-hydroxysteroid dehydrogenase** in its fetal zone, limiting its ability to convert DHEA to progesterone. *Corticosterone* - **Corticosterone** is a glucocorticoid, but it is not the primary or maximum steroid produced by the fetal adrenal gland. - The fetal adrenal gland focuses more on **androgen precursors** necessary for feto-placental estrogen production. *Cortisol* - Although the fetal adrenal gland does produce some **cortisol**, its production significantly increases towards late gestation for organ maturation, it is not the **maximum steroid** produced throughout fetal development, especially compared to DHEA-S. - The pathway for cortisol synthesis is not as prominent in the fetal zone as the pathway for **DHEA-S**.

Question 1

Sperm remain in the epididymis for ____ days?

Accepted Answer

12-14 days

Answer

25-30 days

Answer

5-7 days

Answer

2-3 days

Question 2

Which of the following is not seen in humans?

Accepted Answer

Estrous Cycle

Answer

Menstrual Cycle

Answer

Ovarian Cycle

Answer

Endometrial Cycle

Question 3

The major source of estrogen after menopause is?

Accepted Answer

Aromatization of androgens in adipose tissue

Answer

Aromatization of androgens in granulosa cells of the ovary

Answer

Adrenal production of estrogens

Answer

Aromatization of androgens in theca cells of ovary

Question 4

How many hours does human sperm remain viable in the female genital tract?

Accepted Answer

72-96 hrs

Answer

24-48 hrs

Answer

12-24 hrs

Answer

6-8 hrs

Question 5

MIS is secreted by?

Accepted Answer

Sertoli cell

Answer

Leydig cell

Answer

Granulosa cells

Answer

Theca cells

Question 6

Puberty happens due to pulsatile release of -

Accepted Answer

GnRH

Answer

Testosterone

Answer

LH/ICSH

Answer

Estrogen

Question 7

Mullerian inhibiting substance (MIS) is produced by:

Accepted Answer

Sertoli cells

Answer

Stroma

Answer

Germ cells

Answer

Leydig cells

Question 8

Motor protein responsible for sperm motility is -

Accepted Answer

Dynein

Answer

Actin

Answer

Myosin

Answer

Kinesin

Question 9

Which hormone has permissive role in puberty?

Accepted Answer

Leptin

Answer

GH

Answer

GnRH

Answer

Insulin

Question 10

Maximum steroid produced by fetal adrenal:

Accepted Answer

DHEA-S

Answer

Progesterone

Answer

Corticosterone

Answer

Cortisol

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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