Reproductive Physiology Practice Questions

Q: Ovulation is influenced by

LH. ***LH*** - A surge in **luteinizing hormone (LH)** is the primary trigger for ovulation, inducing the final maturation of the oocyte and rupture of the dominant follicle. - The **LH surge** leads to the release of the ovum from the ovary, typically occurring about 24-36 hours after its onset. *LH+FSH* - While both **LH** and **FSH** are essential for follicular development, the *final act of ovulation itself is primarily driven by the LH surge*, not a combined surge of both. - **FSH** mainly promotes the growth of ovarian follicles in the early to mid-follicular phase. *FSH* - **Follicle-stimulating hormone (FSH)** is crucial for the *development and maturation* of ovarian follicles but does not directly trigger the release of the egg. - High levels of **FSH** alone do not induce ovulation; its role is completed before the actual ovulatory event. *GnRH* - **Gonadotropin-releasing hormone (GnRH)** is released from the hypothalamus and stimulates the pituitary gland to release **LH** and **FSH**. - **GnRH** is a precursor to the release of LH and FSH, but it does not directly act on the ovary to cause ovulation.

Q: Ejection of milk is caused by

Oxytocin. ***Oxytocin*** - **Oxytocin** is responsible for the **milk ejection reflex** (let-down reflex) by stimulating the contraction of **myoepithelial cells** surrounding the alveoli in the mammary glands. - This hormone is released from the **posterior pituitary** in response to suckling, leading to the expulsion of milk from the alveoli into the ducts. *Progesterone* - **Progesterone** is primarily involved in the **development of mammary glands** during pregnancy and preparing them for lactation. - High levels of progesterone during pregnancy actually **inhibit lactation** by blocking prolactin's action; milk production begins after progesterone levels drop postpartum. *Thyroxine* - **Thyroxine** (thyroid hormone) plays a role in **overall metabolism** and is necessary for normal growth and development, but it does not directly cause milk ejection. - While thyroid hormones support general metabolic functions including lactation, they are not involved in the milk ejection reflex itself. *ADH* - **ADH (Antidiuretic Hormone)**, also known as vasopressin, primarily regulates **water balance** by promoting water reabsorption in the kidneys. - Despite being released from the posterior pituitary like oxytocin, ADH has no direct role in the milk ejection reflex.

Q: Separation of first polar body occurs at the time of:

Ovulation. ***Ovulation*** - The **first polar body is extruded just before ovulation**, when the primary oocyte completes **meiosis I** in response to the LH surge. - This division produces a **secondary oocyte** (containing most of the cytoplasm) and the **first polar body** (a small cell with minimal cytoplasm). - The secondary oocyte is then released at ovulation **with the first polar body already separated** in the perivitelline space. *Fertilization* - At fertilization, the secondary oocyte completes **meiosis II** (not meiosis I). - This produces the mature ovum and the **second polar body** (not the first polar body). - The first polar body was already separated before ovulation occurred. *Menstruation* - Menstruation is the shedding of the endometrial lining that occurs when fertilization does not happen. - This is unrelated to oocyte meiotic divisions or polar body formation. *Oocyte maturation* - While oocyte maturation involves the process of meiosis I completion, this term is too broad. - The **specific timing** of first polar body separation is just **before ovulation** in response to the preovulatory LH surge.

Q: Inhibin inhibits secretion of which of the following hormones?

FSH. ***FSH*** - **Inhibin** is a glycoprotein hormone primarily produced by the **gonads (Sertoli cells in males, granulosa cells in females)** and selectively inhibits the secretion of **follicle-stimulating hormone (FSH)** from the anterior pituitary gland. - This negative feedback mechanism helps regulate **gamete production** without significantly affecting **luteinizing hormone (LH)** secretion. *LH releasing hormone* - **Luteinizing hormone-releasing hormone (LHRH)**, also known as **gonadotropin-releasing hormone (GnRH)**, is released from the hypothalamus and stimulates the anterior pituitary to secrete both **LH and FSH**. - Inhibin does not directly inhibit the secretion or action of **LHRH/GnRH**. *LH* - While both **FSH** and **LH** are gonadotropins, inhibin specifically targets **FSH** secretion. - **LH** secretion is primarily regulated by **GnRH** and sex steroids, not directly by inhibin. *Estrogen and progesterone* - **Estrogen** and **progesterone** are steroid hormones produced by the gonads and play crucial roles in regulating the **menstrual cycle** and **reproductive functions**. - Inhibin does not directly inhibit the secretion of **estrogen** and **progesterone**; rather, these steroid hormones exert their own feedback on the **hypothalamus** and **pituitary**.

Q: Follicle stimulating hormone (FSH) receptors are present on:

Granulosa cells. ***Granulosa cells*** - **Granulosa cells** are the **primary target cells** for **FSH** in the ovarian follicles. - FSH binding to its receptors on granulosa cells stimulates their proliferation and differentiation, leading to **follicular growth** and **estrogen production**. - Granulosa cells have the **highest density of FSH receptors** in the ovary, making this the classical answer. *Basement membrane of ovarian follicle* - The **basement membrane** is a structural component that separates the granulosa cells from the theca cells and ovarian stroma. - It does not contain hormone receptors, as its function is primarily for **structural support** and **filtration**. *Leydig cells* - **Leydig cells** are found in the testes, not the ovarian follicle, and are primarily stimulated by **luteinizing hormone (LH)** to produce **androgens**. - Leydig cells do not have FSH receptors; FSH receptors in the testes are found on **Sertoli cells**. *Theca cells* - **Theca cells** are primarily responsible for producing **androgens** (e.g., androstenedione) in response to **LH stimulation**. - **LH receptors predominate** on theca cells, making them the primary LH-responsive cells in the follicle. - While theca interna cells may express some FSH receptors, their density is much lower compared to granulosa cells, and LH remains their primary regulatory hormone. - Androgens produced by theca cells are transported to granulosa cells for aromatization into estrogens.

Q: Ovulation occurs:

14 days prior to next menstruation. ***14 days prior to next menstruation*** - Ovulation consistently occurs approximately **14 days before** the onset of the next menstrual period, regardless of the total cycle length. - This is because the **luteal phase** (from ovulation to menstruation) is relatively constant in duration, typically lasting 14 days. *14 days after menstruation* - This statement assumes a 28-day cycle, which is not universally true, as cycle lengths vary between individuals. - In shorter cycles, ovulation would occur earlier than 14 days after menstruation, and in longer cycles, it would be later. *On 14th day of the cycle* - This is only true for women with a **perfect 28-day menstrual cycle**, which is an average and not universally applicable. - For women with longer cycles (e.g., 35 days), ovulation would occur around day 21, and for shorter cycles (e.g., 21 days), it would occur around day 7. *None of the options* - One of the provided options accurately describes the timing of ovulation in relation to the next menstruation. - Therefore, this choice is incorrect.

Q: Ductal development of breast is caused by

Estrogen. ***Estrogen*** - **Estrogen** is the primary hormone responsible for the **proliferation and branching of ducts** in the breast. - It stimulates the growth of the ductal system during puberty and throughout the menstrual cycle. *Prolactin* - **Prolactin** primarily stimulates **milk production** (lactogenesis) in fully developed breasts, rather than ductal development. - It also plays a role in the differentiation of mammary epithelial cells. *Progesterone* - **Progesterone** is mainly responsible for the development of the **lobuloalveolar structures** (glandular tissue) in the breast, which are responsible for milk secretion. - It works in conjunction with estrogen to prepare the breast for lactation, but its primary role is not ductal growth. *hCG* - **Human chorionic gonadotropin (hCG)** is a hormone produced during **pregnancy**, primarily by the placenta. - While it supports the maintenance of pregnancy and indirectly influences breast changes, it does not directly cause ductal development.

Q: In human males, testosterone is mainly produced by

Leydig cells. ***Leydig cells*** - **Leydig cells** are located in the **interstitial tissue** between the seminiferous tubules in the testes and are responsible for producing **testosterone** in response to luteinizing hormone (LH). - These cells are crucial for the development of male secondary sexual characteristics and spermatogenesis. *Seminiferous tubules* - The **seminiferous tubules** are the primary sites of **spermatogenesis**, the process of sperm production. - While essential for male fertility, they do not directly produce testosterone. *Epididymis* - The **epididymis** is a coiled tube located on the posterior aspect of each testis, where **sperm mature** and are stored. - It plays no role in the production of testosterone. *Sertoli cells* - **Sertoli cells** are found within the **seminiferous tubules** and provide support, nourishment, and protection to developing sperm. - They also produce **androgen-binding protein (ABP)** and inhibin, but not testosterone.

Q: Inhibin B during the follicular phase is primarily secreted by-

Ovarian Follicle. ***Ovarian Follicle*** - **Inhibin B** is primarily secreted by the **granulosa cells** of developing ovarian follicles during the **follicular phase** of the menstrual cycle. - It selectively inhibits **FSH secretion** from the anterior pituitary, providing negative feedback regulation. - Inhibin B levels rise during follicular development and peak at mid-cycle. *Corpus luteum* - The corpus luteum primarily secretes **Inhibin A** (not Inhibin B) during the luteal phase after ovulation. - While both structures produce inhibin, **Inhibin B is specifically associated with follicular activity**, whereas Inhibin A is the luteal phase marker. - The corpus luteum's main hormones are progesterone and estradiol. *Stroma* - The ovarian **stroma** consists of connective tissue and provides structural support. - It contains theca cells that produce androgens but does not directly secrete inhibin. - Its primary role is supportive rather than endocrine. *Surface epithelium of ovary* - The **surface epithelium** is the outermost protective layer of the ovary. - It has no endocrine function and does not produce inhibin or other reproductive hormones. - This layer is primarily involved in covering and protecting the underlying ovarian tissue.

Q: Which finding would be present following selective destruction of sertoli cells?

Increased plasma follicle-stimulating hormone (FSH) levels. ***Increased plasma follicle-stimulating hormone (FSH) levels*** - **Sertoli cells** produce **inhibin B**, which directly and specifically provides **negative feedback** on **FSH** secretion from the anterior pituitary. - Selective destruction of **Sertoli cells** leads to markedly decreased inhibin B, removing this negative feedback on **FSH**, thus causing a **significant increase** in plasma FSH levels. - This is the **most direct and prominent** hormonal finding following Sertoli cell destruction. *Increased plasma luteinizing hormone (LH) levels* - While **LH** may increase somewhat due to impaired testicular function and loss of paracrine support, the **primary and most direct** hormonal change is the increase in **FSH**. - **LH** regulation is mainly through testosterone negative feedback from **Leydig cells**, which remain intact in selective Sertoli cell destruction. - The FSH elevation is far more pronounced and specific to Sertoli cell loss than any LH changes. *Increased plasma testosterone levels* - **Testosterone** is primarily produced by **Leydig cells**, which are not directly affected by selective destruction of Sertoli cells. - In reality, testosterone levels would likely **decrease** (not increase) over time due to loss of spermatogenic tubule integrity and paracrine support from Sertoli cells. - There is no physiological mechanism by which Sertoli cell destruction would increase testosterone. *Increased plasma inhibin levels* - **Inhibin B** is secreted specifically by **Sertoli cells** and acts as a negative regulator of **FSH** release. - Selective destruction of Sertoli cells would lead to a marked **decrease** in inhibin B production, not an increase.

Question 1

Ovulation is influenced by

Accepted Answer

LH

Answer

LH+FSH

Answer

FSH

Answer

GnRH

Question 2

Ejection of milk is caused by

Accepted Answer

Oxytocin

Answer

Progesterone

Answer

Thyroxine

Answer

ADH

Question 3

Separation of first polar body occurs at the time of:

Accepted Answer

Ovulation

Answer

Menstruation

Answer

Fertilization

Answer

Oocyte maturation

Question 4

Inhibin inhibits secretion of which of the following hormones?

Accepted Answer

FSH

Answer

LH releasing hormone

Answer

LH

Answer

Estrogen and progesterone

Question 5

Follicle stimulating hormone (FSH) receptors are present on:

Accepted Answer

Granulosa cells

Answer

Basement membrane of ovarian follicle

Answer

Leydig cells

Answer

Theca cells

Question 6

Ovulation occurs:

Accepted Answer

14 days prior to next menstruation

Answer

14 days after menstruation

Answer

On 14th day of the cycle

Answer

None of the options

Question 7

Ductal development of breast is caused by

Accepted Answer

Estrogen

Answer

Prolactin

Answer

Progesterone

Answer

hCG

Question 8

In human males, testosterone is mainly produced by

Accepted Answer

Leydig cells

Answer

Seminiferous tubules

Answer

Epididymis

Answer

Sertoli cells

Question 9

Inhibin B during the follicular phase is primarily secreted by-

Accepted Answer

Ovarian Follicle

Answer

Corpus luteum

Answer

Stroma

Answer

Surface epithelium of ovary

Question 10

Which finding would be present following selective destruction of sertoli cells?

Accepted Answer

Increased plasma follicle-stimulating hormone (FSH) levels

Answer

Increased plasma luteinizing hormone (LH) levels

Answer

Increased plasma testosterone levels

Answer

Increased plasma inhibin levels

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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