Reproductive system overview — MCQs

10 questions

A 32-year-old man presents to his primary care physician complaining of pain accompanied by a feeling of heaviness in his scrotum. He is otherwise healthy except for a broken arm he obtained while skiing several years ago. Physical exam reveals an enlarged “bag of worms” upon palpation of the painful scrotal region. Shining a light over this area shows that the scrotum does not transilluminate. Which of the following statements is true about the most likely cause of this patient's symptoms?

A group of scientists developed a mouse model to study nondisjunction in meiosis. Their mouse model produced gametes in the following ratio: 2 gametes with 24 chromosomes each and 2 gametes with 22 chromosomes each. In which of the following steps of meiosis did the nondisjunction occur?

At postpartum physical examination, a newborn is found to have male external genitalia. Scrotal examination shows a single palpable testicle in the right hemiscrotum. Ultrasound of the abdomen and pelvis shows an undescended left testis, seminal vesicles, uterus, and fallopian tubes. Chromosomal analysis shows a 46, XY karyotype. Which of the following sets of changes is most likely to be found in this newborn? Legend: Normal = normal levels, ↑ = increased levels, ↓ = decreased levels SRY-gene activity | Müllerian inhibitory factor (MIF) | Testosterone | Dihydrotestosterone (DHT)

A researcher is studying the effects of hormones on different cells within the ovarian follicle. She adds follicle stimulating hormone (FSH) to a culture of ovarian follicle cells. She then measures the activity levels of different enzymes within the cells. Which enzyme and ovarian cell type would be expected to be stimulated by the addition of FSH?

A 25-year-old male visits his physician because of fertility issues with his wife. Physical exam reveals bilateral gynecomastia, elongated limbs, and shrunken testicles. Levels of plasma gonadotropins are elevated. Which of the following is also likely to be increased in this patient:

A researcher is studying gamete production and oogenesis. For her experiment, she decides to cultivate primary oocytes in their arrested state and secondary oocytes just prior to fertilization. When she examines these gametes, she will find that the primary oocytes and secondary oocytes are arrested in which phases of meiosis, respectively?

The Image shows the growth curve of different organs with age. Identify A in the graph.

Identify the labeled structures correctly in the axial CT image of the thorax

Linear growth of bone is disturbed when a fracture occurs in which part?

Q10

The Image shows the growth curve of different organs with age. Identify A in the graph

Reproductive system overview US Medical PG Practice Questions and MCQs

Question 1: A 32-year-old man presents to his primary care physician complaining of pain accompanied by a feeling of heaviness in his scrotum. He is otherwise healthy except for a broken arm he obtained while skiing several years ago. Physical exam reveals an enlarged “bag of worms” upon palpation of the painful scrotal region. Shining a light over this area shows that the scrotum does not transilluminate. Which of the following statements is true about the most likely cause of this patient's symptoms?

A. Equally common on both sides
B. More common on left due to drainage into renal vein (Correct Answer)
C. More common on right due to drainage into renal vein
D. More common on right due to drainage into inferior vena cava
E. More common on left due to drainage into inferior vena cava

Explanation: ***More common on left due to drainage into renal vein*** - The patient's symptoms of scrotal pain, "bag of worms" on palpation, and lack of transillumination are classic for a **left-sided varicocele**. - The longer course and perpendicular drainage of the **left testicular vein** into the left renal vein create higher pressure, making varicocele formation more common on the left. *Equally common on both sides* - Varicoceles are distinctly asymmetrical, with a well-established higher incidence on the left side due to anatomical differences. - Bilateral varicoceles can occur but are less common than isolated left-sided ones and do not support an "equally common" distribution. *More common on right due to drainage into renal vein* - The right testicular vein typically drains directly into the **inferior vena cava (IVC)**, not the renal vein, which is a lower pressure system compared to the left. - Therefore, anatomical factors do not favor varicocele formation on the right side due to drainage into the renal vein. *More common on right due to drainage into inferior vena cava* - While the right testicular vein drains into the IVC, this direct drainage path is associated with good venous return and a lower risk of varicocele. - A right-sided varicocele is less common and, if present, should prompt investigation for retroperitoneal mass obstructing the IVC or right testicular vein. *More common on left due to drainage into inferior vena cava* - The left testicular vein typically drains into the **left renal vein**, not directly into the inferior vena cava. - This anatomical description is incorrect and does not explain the higher incidence of left-sided varicoceles.

Question 2: A group of scientists developed a mouse model to study nondisjunction in meiosis. Their mouse model produced gametes in the following ratio: 2 gametes with 24 chromosomes each and 2 gametes with 22 chromosomes each. In which of the following steps of meiosis did the nondisjunction occur?

A. Telophase I
B. Metaphase II
C. Anaphase I (Correct Answer)
D. Anaphase II
E. Metaphase I

Explanation: ***Anaphase I*** - Nondisjunction during **Anaphase I** occurs when homologous chromosomes fail to separate properly, meaning both homologs of a chromosome pair go to the same pole. - This results in two secondary gametocytes with abnormal chromosome numbers: one with n+1 chromosomes (24) and one with n-1 chromosomes (22). - When meiosis II proceeds normally, each abnormal secondary gametocyte divides to produce 2 identical gametes, resulting in **all 4 gametes being abnormal** in a 2:2 ratio (two n+1 and two n-1), matching the observed pattern. *Telophase I* - **Telophase I** is the final stage of meiosis I where chromosomes arrive at the poles and the cell divides, but it's not where the initial separation error (nondisjunction) occurs. - Nondisjunction happens due to a failure of **chromosome segregation**, which is a process of anaphase, not telophase. *Metaphase II* - **Metaphase II** involves the alignment of sister chromatids at the metaphase plate in secondary gametocytes. Nondisjunction at this stage would involve sister chromatids failing to separate. - Nondisjunction in Metaphase II (or Anaphase II) would lead to 2 normal gametes (23 chromosomes), one gamete with n+1 (24 chromosomes), and one gamete with n-1 (22 chromosomes), which differs from the given ratio. *Anaphase II* - **Nondisjunction in Anaphase II** would involve the failure of sister chromatids to separate in one of the secondary gametocytes. - This would produce two normal gametes (23 chromosomes), one gamete with 24 chromosomes (n+1), and one gamete with 22 chromosomes (n-1), which is not the 2:2 ratio observed. *Metaphase I* - **Metaphase I** is characterized by the alignment of homologous chromosome pairs at the metaphase plate. While an issue here could precede nondisjunction, the actual event of failed separation occurs during anaphase. - No separation of chromosomes occurs in Metaphase I; it is the stage of **chromosome alignment** before segregation.

Question 3: At postpartum physical examination, a newborn is found to have male external genitalia. Scrotal examination shows a single palpable testicle in the right hemiscrotum. Ultrasound of the abdomen and pelvis shows an undescended left testis, seminal vesicles, uterus, and fallopian tubes. Chromosomal analysis shows a 46, XY karyotype. Which of the following sets of changes is most likely to be found in this newborn? Legend: Normal = normal levels, ↑ = increased levels, ↓ = decreased levels SRY-gene activity | Müllerian inhibitory factor (MIF) | Testosterone | Dihydrotestosterone (DHT)

A. Normal normal normal ↓
B. ↓ ↓ ↓ ↓
C. Normal ↓ normal normal (Correct Answer)
D. ↓ ↓ normal normal
E. Normal normal ↑ ↑

Explanation: ***Normal ↓ Normal Normal*** - A 46, XY karyotype with male external genitalia indicates **normal SRY-gene activity** and normal **testosterone** production, as these are critical for male sexual differentiation. - The presence of a **uterus and fallopian tubes** in a 46, XY individual is characteristic of persistent **Müllerian duct syndrome**, caused by a **deficiency or insensitivity to Müllerian Inhibiting Factor (MIF)**, leading to a decreased level of MIF. *Normal Normal Normal ↓* - This pattern would suggest normal initial male differentiation but an issue downstream, possibly with **5-alpha-reductase deficiency** (leading to decreased DHT) and normal MIF, which would prevent Müllerian structure development. - The presence of a **uterus and fallopian tubes** contradicts normal MIF levels. *↓ ↓ ↓ ↓* - This combination indicates severe defects in all aspects of male sexual development, which would lead to **female external genitalia** or ambiguous genitalia, not male external genitalia. - Such low levels would also prevent the formation of a palpable testis, and a 46, XY karyotype with female internal structures due to low testosterone and MIF would be highly unlikely to produce male external genitalia. *↓ ↓ Normal Normal* - While low MIF would explain the presence of a uterus and fallopian tubes, a **decreased SRY-gene activity** would prevent the development of testes and lead to ambiguous or female external genitalia, rather than male external genitalia. - Normal testosterone and DHT with decreased SRY gene activity is a contradictory combination, as testosterone production is dependent on the presence of testes. *Normal Normal ↑ ↑* - This profile would result in normal male internal and external genitalia, without the presence of **uterus or fallopian tubes**. - Increased levels of androgens are typically found in conditions like **congenital adrenal hyperplasia** in XX individuals, leading to virilization, but are not consistent with the internal structures seen here.

Question 4: A researcher is studying the effects of hormones on different cells within the ovarian follicle. She adds follicle stimulating hormone (FSH) to a culture of ovarian follicle cells. She then measures the activity levels of different enzymes within the cells. Which enzyme and ovarian cell type would be expected to be stimulated by the addition of FSH?

A. Desmolase; theca interna cell
B. Aromatase; theca externa cell
C. Aromatase; granulosa cell (Correct Answer)
D. Desmolase; granulosa cell
E. Aromatase; theca interna cell

Explanation: ***Aromatase; granulosa cell*** - **FSH** acts directly on **granulosa cells** to stimulate their proliferation and differentiation. - One of the key functions of stimulated granulosa cells is the production of **aromatase**, an enzyme responsible for converting **androgens** (produced by theca cells) into **estrogens**. *Desmolase; theca interna cell* - **Desmolase** (specifically cholesterol desmolase, or CYP11A1) is found in **theca interna cells** and is responsible for converting cholesterol into **androgens**. - Theca interna cell activity, including desmolase, is primarily stimulated by **LH**, not FSH. *Aromatase; theca externa cell* - The **theca externa cells** are primarily connective tissue and lack significant endocrine function, including aromatase activity. - **Aromatase** is predominantly present in the granulosa cells. *Desmolase; granulosa cell* - While granulosa cells are crucial for estrogen synthesis via aromatase, they do not produce **desmolase**. - **Desmolase** is the key enzyme in theca interna cells for androgen synthesis. *Aromatase; theca interna cell* - **Theca interna cells** produce **androgens** under the influence of **LH** and do not express **aromatase**. - **Aromatase** is exclusively expressed in the **granulosa cells** and converts these androgens into estrogens.

Question 5: A 25-year-old male visits his physician because of fertility issues with his wife. Physical exam reveals bilateral gynecomastia, elongated limbs, and shrunken testicles. Levels of plasma gonadotropins are elevated. Which of the following is also likely to be increased in this patient:

A. Testosterone
B. Inhibin
C. Sertoli cells
D. Ejaculatory sperm
E. Aromatase (Correct Answer)

Explanation: ***Correct: Aromatase*** - The symptoms described (gynecomastia, elongated limbs, shrunken testicles, elevated gonadotropins) are characteristic of **Klinefelter syndrome (47, XXY)**. - In Klinefelter syndrome, **increased aromatase activity** (particularly in adipose tissue) leads to enhanced conversion of androgens to estrogens, resulting in elevated estrogen levels. - This increased estrogen contributes to gynecomastia and exacerbates the hypogonadism and fertility issues. *Incorrect: Testosterone* - In Klinefelter syndrome, **testosterone levels are typically low** due to primary testicular failure, which explains the shrunken testicles and infertility. - The elevated gonadotropins (LH and FSH) are a compensatory response to the low testosterone. *Incorrect: Inhibin* - **Inhibin** is produced by **Sertoli cells** and normally suppresses FSH release. - In Klinefelter syndrome, damage to the seminiferous tubules and impaired Sertoli cell function lead to **decreased inhibin production**, contributing to elevated FSH. *Incorrect: Sertoli cells* - Klinefelter syndrome is characterized by **dysgenesis and reduced numbers of Sertoli cells** within the seminiferous tubules, leading to impaired spermatogenesis and fertility issues. - This reduction in Sertoli cells also contributes to decreased inhibin levels. *Incorrect: Ejaculatory sperm* - Individuals with Klinefelter syndrome typically have **azoospermia** or severe oligozoospermia due to profound testicular dysfunction and seminiferous tubule atrophy. - This significantly impairs their fertility and is a common reason for presenting with infertility.

Question 6: A researcher is studying gamete production and oogenesis. For her experiment, she decides to cultivate primary oocytes in their arrested state and secondary oocytes just prior to fertilization. When she examines these gametes, she will find that the primary oocytes and secondary oocytes are arrested in which phases of meiosis, respectively?

A. Anaphase I; anaphase II
B. Interphase I; prophase II
C. Metaphase I; metaphase II
D. Metaphase I; prophase II
E. Prophase I; metaphase II (Correct Answer)

Explanation: ***Prophase I; metaphase II*** - **Primary oocytes** are arrested in **prophase I** from embryonic development until puberty, when they resume meiosis in preparation for ovulation. - **Secondary oocytes** are immediately arrested in **metaphase II** after completing meiosis I, and they will remain in this stage until fertilization occurs. *Anaphase I; anaphase II* - **Anaphase I** involves the separation of **homologous chromosomes**, and **anaphase II** involves the separation of **sister chromatids**. Neither primary nor secondary oocytes are arrested in these stages. - Meiotic arrest occurs at earlier stages to prevent further division until specific triggers (ovulation or fertilization) are met. *Interphase I; prophase II* - **Interphase I** precedes meiosis I, during which DNA replication occurs, and it is not a stage of meiotic arrest for primary oocytes. - **Prophase II** is a transient stage in meiosis II, and secondary oocytes are arrested later in **metaphase II**, not prophase II. *Metaphase I; metaphase II* - While **secondary oocytes** are indeed arrested in **metaphase II**, **primary oocytes** are arrested much earlier in **prophase I**, not metaphase I. - The arrest in metaphase I is temporary for primary oocytes as they complete meiosis I to form secondary oocytes upon hormonal signaling. *Metaphase I; prophase II* - **Primary oocytes** are arrested in **prophase I**, not metaphase I. Meiosis I is completed before ovulation, leading to the formation of secondary oocytes. - **Secondary oocytes** are arrested in **metaphase II**, not prophase II, awaiting fertilization to complete meiosis II.

Question 7: The Image shows the growth curve of different organs with age. Identify A in the graph.

A. Brain Growth
B. Somatic Growth
C. Lymphoid Growth (Correct Answer)
D. Gonadal Growth
E. Reproductive Growth

Explanation: ***Lymphoid Growth*** - Curve 'A' shows a rapid increase in size during **childhood**, peaking around **10-12 years of age**, and then declining to adult levels. - This pattern is characteristic of **lymphoid tissues** (e.g., thymus, lymph nodes, tonsils), which are larger relative to body size in childhood and undergo involution post-puberty. *Brain Growth* - **Neural growth** (like the brain) typically shows very rapid growth in early childhood, reaching close to adult size by about 6-7 years of age, and then leveling off. - Curve 'A' continues to grow rapidly much longer than expected for brain development and then shows a distinct decline. *Somatic Growth* - **General somatic growth** (e.g., body as a whole) shows a sigmoid curve, with rapid growth in infancy and adolescence, and a plateau in adulthood. - Curve 'A' peaks significantly above the 100% mark and then declines, which is not characteristic of overall somatic growth. *Gonadal Growth* - **Genital (gonadal) growth** remains relatively flat until puberty, after which it experiences a rapid increase. - Curve 'A' shows significant growth in early childhood and a peak before puberty, which is inconsistent with typical gonadal development. *Reproductive Growth* - **Reproductive growth** follows the same pattern as gonadal growth, remaining minimal until puberty with subsequent rapid increase. - Curve 'A' demonstrates early childhood growth and pre-pubertal peak, which does not match the reproductive growth pattern.

Question 8: Identify the labeled structures correctly in the axial CT image of the thorax

A. A - Pulmonary trunk, B - Ascending aorta, C - Superior vena cava, D - Descending aorta
B. A - Superior vena cava, B - Pulmonary trunk, C - Ascending aorta, D - Descending aorta
C. A - Ascending aorta, B - Pulmonary trunk, C - Superior vena cava, D - Descending aorta (Correct Answer)
D. A - Ascending aorta, B - Superior vena cava, C - Pulmonary trunk, D - Descending aorta
E. A - Pulmonary trunk, B - Superior vena cava, C - Ascending aorta, D - Descending aorta

Explanation: ***A - Ascending aorta, B - Pulmonary trunk, C - Superior vena cava, D - Descending aorta*** - **A** points to the **ascending aorta**, which is the large artery arising from the left ventricle and supplying oxygenated blood to the systemic circulation. On this axial view, it is typically located anterior and to the right of the pulmonary artery. - **B** points to the **pulmonary trunk**, which emerges from the right ventricle and bifurcates into the pulmonary arteries to carry deoxygenated blood to the lungs. It is positioned anterior and to the left of the ascending aorta at this level. - **C** points to the **superior vena cava**, a large vein that collects deoxygenated blood from the upper half of the body and drains into the right atrium. It is typically located to the right and slightly posterior to the ascending aorta at this level. - **D** points to the **descending aorta**, which continues from the aortic arch downwards through the chest and abdomen to supply blood to the lower body. It is visible posteriorly and to the left of the vertebral body on this axial CT image. *A - Pulmonary trunk, B - Ascending aorta, C - Superior vena cava, D - Descending aorta* - This option incorrectly identifies A as the pulmonary trunk and B as the ascending aorta; the **ascending aorta** is typically positioned more anteriorly and to the right compared to the **pulmonary trunk** at this level. - The relative positions of the pulmonary trunk and ascending aorta are swapped, leading to an incorrect labeling. *A - Superior vena cava, B - Pulmonary trunk, C - Ascending aorta, D - Descending aorta* - This option incorrectly identifies A as the superior vena cava and C as the ascending aorta. The **superior vena cava** is typically located to the right of the ascending aorta, not anterior-central. - The **ascending aorta** is usually the most anterior and central great vessel in the mediastinum at this level, which does not correspond to C. *A - Ascending aorta, B - Superior vena cava, C - Pulmonary trunk, D - Descending aorta* - This option incorrectly identifies B as the superior vena cava and C as the pulmonary trunk. **Superior vena cava** is a venous structure and is not typically located in the position of B, which is an arterial structure (pulmonary trunk). - The **pulmonary trunk** is usually more anterior and central than the position of C, which correctly identifies the superior vena cava in other options.

Question 9: Linear growth of bone is disturbed when a fracture occurs in which part?

A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Epiphyseal plate (Correct Answer)
E. Periosteum

Explanation: ***Epiphyseal plate*** - The **epiphyseal plate**, also known as the **growth plate**, is a cartilaginous disc responsible for the **longitudinal growth** of long bones. - A fracture in this region can damage the **chondrocytes** and disrupt the normal process of endochondral ossification, leading to **growth arrest** or limb length discrepancy. *Epiphysis* - The **epiphysis** is the end part of a long bone, often covered by **articular cartilage**, forming a joint. - While an epiphyseal fracture can affect joint function, it typically does not directly disturb the **linear growth** of the bone unless it extends into the growth plate. *Diaphysis* - The **diaphysis** is the main or midsection of a long bone, composed primarily of **compact bone**. - Fractures in the diaphysis generally heal through **callus formation** and remodeling, usually without significantly impacting the overall **linear growth** of the bone. *Metaphysis* - The **metaphysis** is the wider portion of a long bone, adjacent to the growth plate and diaphysis. - Though highly vascular, fractures to the metaphysis usually heal well and do not directly control **linear bone growth** like the epiphyseal plate. *Periosteum* - The **periosteum** is the fibrous membrane covering the outer surface of bones, important for **appositional growth** (bone widening) and fracture healing. - While it contains osteogenic cells that contribute to bone repair and thickness, it does not control **longitudinal bone growth**, which is the function of the epiphyseal plate.

Question 10: The Image shows the growth curve of different organs with age. Identify A in the graph

A. Brain Growth (Correct Answer)
B. Somatic Growth
C. Lymphoid Growth
D. Gonadal Growth
E. Reproductive Growth

Explanation: ***Brain Growth*** - This graph shows a rapid increase in size during early childhood, reaching near-adult proportions by age 5-6, which is characteristic of **brain development**. - The brain undergoes significant myelinization and neuronal growth in the first few years of life, reflected in this steep curve. *Somatic Growth* - **Somatic growth** (body as a whole) generally follows a more gradual S-shaped curve, with two major growth spurts: one in infancy and another during puberty. - It does not plateau as early as curve A, but continues to increase significantly through adolescence. *Lymphoid Growth* - **Lymphoid tissues** (e.g., thymus, lymph nodes) show a unique growth pattern, peaking in size around 10-12 years of age and then involuting or decreasing in size during adolescence. - This pattern is distinctly different from curve A, which continuously increases and plateaus. *Gonadal Growth* - **Gonadal growth** (reproductive organs) typically shows minimal growth during childhood, with a pronounced and rapid increase in size starting at puberty (around 10-14 years of age). - This growth pattern is a later and more delayed surge compared to what is depicted in curve A. *Reproductive Growth* - **Reproductive growth** follows essentially the same pattern as gonadal growth, with minimal development during childhood and rapid acceleration during puberty. - Like gonadal tissues, reproductive organs show their major growth spurt much later than the early plateau seen in curve A.

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