Reproductive Physiology — MCQs
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After ovulation, the oocyte is:
Absence or mutation of SRY gene results in ?
Milk production in pregnancy is inhibited by :
A 21-year-old primigravida woman visits the clinic in her 22nd week of gestation as part of her antenatal care. She has no complaints. Past medical history is unremarkable. Her only medication is a prenatal vitamin. Her temperature is 37.0°C (98.6°F), blood pressure is 110/70 mm Hg, pulse rate is 78/min, and respiration rate is 20/min. Physical examination is consistent with the gestational age of her pregnancy with no abnormalities noted. Urine dipstick is normal. Which of the following is the current primary location for fetal myelopoiesis at this stage of development?
In this normal menstrual cycle graph, the mark 'X' represents levels of which hormone?
Inhibin is secreted by:
There is a mid-cycle shift in the basal body temperature (BBT) after ovulation in women. This is caused by :
Dihydrotestosterone acts on
Transplacental exchanges that take place are essential to the well being of the fetus. Which of those listed below is NOT a method?
Ovulation is primarily caused by preovulatory surge of:
Reproductive Physiology Indian Medical PG Practice Questions and MCQs
Question 361: After ovulation, the oocyte is:
- A. Primary oocyte arrested in prophase II
- B. Secondary oocyte arrested in prophase II
- C. Secondary oocyte arrested in metaphase II (Correct Answer)
- D. Primary oocyte arrested in prophase I
Explanation: ***Secondary oocyte arrested in metaphase II*** - After ovulation, the **oocyte** has completed **meiosis I** and extruded the **first polar body**, becoming a secondary oocyte. - It then arrests in **metaphase II** and will only complete meiosis II upon fertilization by a sperm. *Primary oocyte arrested in prophase II* - A **primary oocyte** is the stage before meiosis I is completed, and it is arrested in **prophase I** at birth, not prophase II. - Oocytes do not arrest in **prophase II** during normal meiotic development. *Secondary oocyte arrested in prophase II* - While it is a **secondary oocyte** that is ovulated, it is arrested in **metaphase II**, not prophase II. - **Prophase II** is a transient stage that occurs just before metaphase II, and arrest at this stage is not typical for the ovulated oocyte. *Primary oocyte arrested in prophase I* - This describes the state of the oocyte from **fetal development** until just before ovulation. - A **primary oocyte** completes meiosis I only in response to the **LH surge** before ovulation.
Question 362: Absence or mutation of SRY gene results in ?
- A. Hydrocele testis
- B. Undescended testis
- C. None of the options
- D. Gonadal dysgenesis (Correct Answer)
Explanation: ***Gonadal dysgenesis*** - The **SRY gene** (Sex-determining region Y gene) is critical for initiating **male sexual differentiation**; its presence leads to testicular development. - Absence or mutation of the SRY gene prevents proper testicular development, leading to **gonadal dysgenesis**, where the gonads are either absent or rudimentary, often resulting in a **female phenotype** despite a XY genotype. *Hydrocele testis* - This condition involves an accumulation of fluid around the testis, which is typically due to a **patent tunica vaginalis** or fluid imbalance. - It does not directly result from a genetic mutation in the SRY gene affecting initial **gonadal development**. *Undescended testis* - This condition (cryptorchidism) refers to the failure of one or both testes to descend into the scrotum. - While it can have genetic components, it is not a direct consequence of an SRY gene absence or mutation, which primarily affects the **formation of the gonad itself**. *None of the options* - This option is incorrect because **gonadal dysgenesis** is a direct and well-established consequence of SRY gene absence or mutation. - The SRY gene's primary role is to trigger the development of the testis, and its dysfunction leads to profound abnormalities in **gonadal formation**.
Question 363: Milk production in pregnancy is inhibited by :
- A. Low luteinizing hormone
- B. Low thyroid-stimulating hormone
- C. High estrogen (Correct Answer)
- D. Human somatomammotropin
Explanation: ***High estrogen*** - High levels of **estrogen** and progesterone during pregnancy inhibit milk production by blocking the action of **prolactin** on the mammary glands. - After delivery, the sudden drop in these hormones removes the inhibition, allowing prolactin to stimulate **lactogenesis**. *Low luteinizing hormone* - **Luteinizing hormone (LH)** is primarily involved in ovulation and corpus luteum formation, not directly in the inhibition of milk production. - Low LH levels would impact fertility but not have a direct inhibitory effect on lactation. *Low thyroid-stimulating hormone* - **Thyroid-stimulating hormone (TSH)** regulates thyroid function, which can indirectly affect metabolism and overall well-being. - While **hypothyroidism** can impact milk supply, low TSH itself is not a direct inhibitor of milk production. *Human somatomammotropin* - **Human placental lactogen (HPL)**, also known as human chorion somatomammotropin, is produced by the placenta. - It promotes mammary gland development and has weak lactogenic properties but does not inhibit milk production.
Question 364: A 21-year-old primigravida woman visits the clinic in her 22nd week of gestation as part of her antenatal care. She has no complaints. Past medical history is unremarkable. Her only medication is a prenatal vitamin. Her temperature is 37.0°C (98.6°F), blood pressure is 110/70 mm Hg, pulse rate is 78/min, and respiration rate is 20/min. Physical examination is consistent with the gestational age of her pregnancy with no abnormalities noted. Urine dipstick is normal. Which of the following is the current primary location for fetal myelopoiesis at this stage of development?
- A. Thymus
- B. Liver (Correct Answer)
- C. Yolk sac
- D. Spleen
Explanation: ***Liver*** - The **liver** is the primary site of **fetal erythropoiesis** (and myelopoiesis) between approximately 6 weeks of gestation and the end of the second trimester (around 24-28 weeks). - At 22 weeks of gestation, the liver's role in blood cell production is dominant before the bone marrow takes over. *Thymus* - The thymus is primarily involved in **T-lymphocyte maturation** and selection, not broad myelopoiesis. - While it is a lymphoid organ, its role is specific to adaptive immunity development. *Yolk sac* - The **yolk sac** is the earliest site of **hematopoiesis**, primarily during the **first 6 weeks of gestation**. - Its contribution to blood cell production significantly declines after the first trimester. *Spleen* - The **spleen** plays a **secondary role** in fetal hematopoiesis, primarily aiding in erythropoiesis later in gestation. - It is not the primary site for myelopoiesis at 22 weeks.
Question 365: In this normal menstrual cycle graph, the mark 'X' represents levels of which hormone?
- A. LH
- B. FSH
- C. Progesterone (Correct Answer)
- D. Estrogen
Explanation: ***Progesterone*** - The mark 'X' (blue line) represents a hormone that significantly rises during the **luteal phase** after ovulation, reaching its peak around day 21-24 and then declining if pregnancy does not occur. - This pattern is characteristic of **progesterone**, which is primarily produced by the corpus luteum after ovulation to prepare the uterus for potential implantation. *LH* - **Luteinizing Hormone (LH)** is characterized by a sharp, transient peak just before ovulation (around day 14), which triggers the release of the egg. The blue line does not show this pre-ovulatory surge. - After ovulation, LH levels generally fall and remain relatively low throughout the luteal phase, unlike the sustained high levels shown by the blue line. *FSH* - **Follicle-Stimulating Hormone (FSH)** levels are typically higher during the early follicular phase, promoting follicle growth, and then decrease as estrogen rises. There is a smaller, transient peak around ovulation. - The blue line's profile, with its primary peak in the mid-luteal phase, does not match the typical FSH secretion pattern. *Estrogen* - **Estrogen** (specifically estradiol) typically shows a prominent peak during the late follicular phase, preceding the LH surge, and a secondary, smaller peak in the mid-luteal phase. - The blue line's peak is much higher and more sustained during the luteal phase than expected for estrogen, which is usually represented by the red curve in such graphs.
Question 366: Inhibin is secreted by:
- A. Peg cells
- B. Leydig cells
- C. Sertoli cells (Correct Answer)
- D. Interstitial cells
Explanation: ***Sertoli cells*** - **Sertoli cells** are located in the seminiferous tubules of the testes and play a crucial role in spermatogenesis. - They secrete **inhibin**, a hormone that selectively inhibits the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. *Peg cells* - **Peg cells** (non-ciliated secretory cells) are found in the lining of the fallopian tubes, not the testes. - They produce **tubal fluid** which nourishes the ovum and spermatozoa, and aids in sperm capacitation. *Leydig cells* - **Leydig cells** are found in the interstitial tissue between the seminiferous tubules of the testes. - Their primary function is to produce and secrete **androgens**, such as testosterone, in response to luteinizing hormone (LH). *Interstitial cells* - This term is a general descriptor for cells located in the spaces between functional tissues or organs. - In the context of the testes, **Leydig cells** are the primary interstitial cells responsible for hormone production, while **Sertoli cells** are part of the seminiferous tubules.
Question 367: There is a mid-cycle shift in the basal body temperature (BBT) after ovulation in women. This is caused by :
- A. FSH-peak
- B. Progesterone (Correct Answer)
- C. Oestradiol
- D. LH-peak
Explanation: **Progesterone** - After ovulation, the ruptured follicle transforms into the **corpus luteum**, which primarily secretes progesterone. - **Progesterone** is a **thermogenic hormone**, meaning it directly causes an increase in basal body temperature (BBT) by about 0.5 to 1.0°F (0.2 to 0.5°C). *FSH-peak* - The **FSH-peak** occurs earlier in the follicular phase, stimulating follicular growth. - It does not directly influence basal body temperature in the post-ovulatory phase. *Oestradiol* - **Oestradiol** (estrogen) levels are highest just before ovulation, which can have a slight temperature-lowering effect or no significant impact on BBT. - It is not responsible for the sustained post-ovulatory temperature rise. *LH-peak* - The **LH-peak** triggers ovulation but does not directly cause the sustained post-ovulatory increase in BBT. - The temperature shift due to LH is transient and not sustained without subsequent progesterone production.
Question 368: Dihydrotestosterone acts on
- A. Pituitary
- B. External genitalia (Correct Answer)
- C. Internal genitalia
- D. Testis
Explanation: ***External genitalia*** - **Dihydrotestosterone (DHT)** is critical for the development of **male external genitalia** during fetal development. - In adulthood, **DHT** is responsible for the growth of the **prostate** and secondary male sexual characteristics like **facial hair** and **balding**. *Pituitary* - The **pituitary gland** is primarily regulated by **gonadotropin-releasing hormone (GnRH)** from the hypothalamus and feedback from **gonadal steroids** like **testosterone** and **estrogen**, not directly by **DHT**. - **DHT** does not exert significant direct action on the anterior pituitary to regulate gonadotropin release. *Internal genitalia* - The development of **internal male genitalia**, such as the **epididymis**, **vas deferens**, and **seminal vesicles**, is primarily mediated by **testosterone** directly, not **DHT**. - **Testosterone** acts on the **Wolffian ducts** to promote their differentiation into the internal male reproductive structures. *Testis* - The **testis** is the primary site of **testosterone production** and conversion to **DHT** by **5α-reductase**. - While **DHT** is produced within the testis, its main actions are on peripheral target tissues rather than directly regulating testicular function.
Question 369: Transplacental exchanges that take place are essential to the well being of the fetus. Which of those listed below is NOT a method?
- A. Active transport
- B. Simple diffusion
- C. Endocytosis
- D. Exocytosis (Correct Answer)
Explanation: ***Exocytosis*** - **Exocytosis** is the process where cells release substances by fusing vesicles with the cell membrane and expelling their contents outside the cell. - While exocytosis occurs as part of **transcytosis** (where substances are taken up by endocytosis on one side and released by exocytosis on the other), it is **not classified as an independent primary mechanism** of transplacental transport in standard physiology teaching. - The major recognized mechanisms of transplacental exchange are: simple diffusion, facilitated diffusion, active transport, and endocytosis/pinocytosis. *Active transport* - **Active transport** uses ATP energy to move substances against their concentration gradients across the placental membrane. - Essential for transporting **amino acids, water-soluble vitamins (B, C), calcium, iron, and iodine** from mother to fetus. - Ensures the fetus receives adequate supplies even when maternal concentrations are low. *Simple diffusion* - **Simple diffusion** is a passive process where substances move down their concentration gradient directly across cell membranes. - This is the **primary mechanism** for exchange of **respiratory gases (O₂, CO₂)**, water, and **lipid-soluble substances** (steroid hormones, fatty acids, fat-soluble vitamins) across the placenta. *Endocytosis* - **Endocytosis** involves cells internalizing substances by engulfing them via membrane invagination, forming vesicles. - **Receptor-mediated endocytosis** is crucial for transfer of **maternal IgG antibodies** to provide passive immunity to the fetus. - **Pinocytosis** (fluid-phase endocytosis) allows transfer of other large molecules and proteins.
Question 370: Ovulation is primarily caused by preovulatory surge of:
- A. Progesterone
- B. Estradiol
- C. Luteinizing hormone (Correct Answer)
- D. Follicle stimulating hormone
Explanation: ***Luteinizing hormone*** - The **luteinizing hormone (LH) surge** is the direct trigger for ovulation, causing the mature follicle to rupture and release the ovum. - This surge is induced by a rapid increase in **estradiol** levels from the dominant follicle, which switches from negative to positive feedback on the hypothalamus and pituitary. *Progesterone* - While progesterone levels begin to rise *after* the LH surge and play a crucial role in maintaining the uterine lining for potential pregnancy, it is **not the primary cause** of ovulation itself. - Progesterone levels are relatively low during the follicular phase and only increase significantly after ovulation, particularly from the **corpus luteum**. *Estradiol* - **Estradiol** levels *rise significantly* during the follicular phase and ultimately *trigger* the LH surge through a positive feedback mechanism. - However, estradiol itself does **not directly cause follicular rupture and ovum release**; it primes the system for the LH surge to perform that function. *Follicle stimulating hormone* - **Follicle-stimulating hormone (FSH)** is primarily responsible for the **growth and maturation of ovarian follicles** during the follicular phase of the menstrual cycle. - Although FSH levels also experience a modest surge around the time of ovulation, it is the **LH surge** that directly causes follicular rupture and ovum release.
Practice by Chapter
Male Reproductive Physiology
Practice Questions
Spermatogenesis and Sperm Function
Practice Questions
Female Reproductive Physiology
Practice Questions
Menstrual Cycle
Practice Questions
Ovulation and Fertilization
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Physiology of Pregnancy
Practice Questions
Parturition
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Lactation
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Sexual Differentiation and Development
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Reproductive Aging
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