Fetal Endocrine Development — MCQs
If a baby has a XX or XY genotype, normal internal gonads, but ambiguous external genitalia, it is called?
In development of male fetus following statements are true except
3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -
If blood supply to hypothalamus is interrupted through median eminence which hormone will have normal secretion?
Which of the following statements about placental hormones is true?
Estrogen is secreted during pregnancy, mostly by which organ?
What is the incorrect statement?
Hypothalamus increases release of all hormones from the pituitary except ?
During early pregnancy (first trimester), estrogen is primarily secreted by which of the following structures?
Hypothyroidism in pregnancy is most likely associated with which of the following?
Fetal Endocrine Development Indian Medical PG Practice Questions and MCQs
Question 1: If a baby has a XX or XY genotype, normal internal gonads, but ambiguous external genitalia, it is called?
- A. True hermaphrodite
- B. Disorder of Sex Development (DSD) (Correct Answer)
- C. Intersex (outdated term)
- D. Any of the above
- E. Pseudohermaphrodite
Explanation: ***Disorder of Sex Development (DSD)*** - This is the **current preferred medical terminology** that encompasses conditions where there is a discrepancy between chromosomal sex, gonadal sex, and anatomical sex. - The scenario described—normal XX or XY genotype and normal internal gonads with **ambiguous external genitalia**—fits the definition of a DSD. - This **umbrella term** has replaced older terminology and is the most appropriate answer in modern medical practice. *True hermaphrodite* - A true hermaphrodite, now referred to as **ovotesticular DSD**, possesses both ovarian and testicular tissue simultaneously. - The question specifies **normal internal gonads** (either ovaries or testes, not both), which excludes this diagnosis. *Intersex (outdated term)* - While "intersex" was historically used to describe individuals with atypical sexual characteristics, it is now considered an **outdated and less precise** term in medical contexts. - "Disorder of Sex Development" is the preferred and more comprehensive medical classification. *Pseudohermaphrodite* - This was the **classical medical term** for exactly this presentation: normal chromosomal sex and appropriate internal gonads but ambiguous external genitalia. - Examples include 46,XX DSD with virilization (e.g., **congenital adrenal hyperplasia**) or 46,XY DSD with undervirilization (e.g., **androgen insensitivity syndrome**). - This term has been **replaced by DSD terminology** in modern medical practice to avoid stigmatizing language. *Any of the above* - While multiple terms have been used historically, **DSD is the most accurate and currently accepted medical term** for this specific presentation. - Therefore, this option is incorrect as it suggests all answers are equally valid.
Question 2: In development of male fetus following statements are true except
- A. During intrauterine life, testes do not produce hormones essential for male development. (Correct Answer)
- B. Around 8 weeks internal and external genitalia differentiates into male pattern
- C. Gene on short arm of Y chromosome directs testes development
- D. Antimullerian hormone inhibits development of mullerian system in male fetus
Explanation: *During intrauterine life, testes do not produce hormones essential for male development.* - This statement is **INCORRECT** and is the answer to this EXCEPT question. - The **fetal testes** actively produce essential hormones during intrauterine life including **testosterone** (from Leydig cells) and **Anti-Müllerian Hormone/AMH** (from Sertoli cells). - Testosterone is converted to **dihydrotestosterone (DHT)** which drives development of male external genitalia. - These hormones are absolutely essential for **masculinization of internal and external genitalia** and regression of female structures. ***Around 8 weeks internal and external genitalia differentiates into male pattern.*** - This statement is correct. Sexual differentiation begins around **7-8 weeks of gestation**. - Under the influence of **testosterone and DHT** produced by fetal testes, the indifferent genitalia differentiate into male pattern. - The Wolffian ducts develop into male internal structures (epididymis, vas deferens, seminal vesicles). ***Gene on short arm of Y chromosome directs testes development.*** - This statement is correct. The **SRY gene (Sex-determining Region Y)** located on the **short arm (p arm) of the Y chromosome** is the master regulator of testis determination. - SRY expression triggers differentiation of the indifferent gonads into testes around 6-7 weeks. - Without SRY, the default pathway leads to ovarian development. ***Antimullerian hormone inhibits development of mullerian system in male fetus.*** - This statement is correct. **Anti-Müllerian Hormone (AMH)**, also called Müllerian-Inhibiting Substance (MIS), is secreted by **Sertoli cells** of the fetal testes. - AMH causes **regression of the Müllerian ducts** (paramesonephric ducts) around 8-10 weeks. - Without AMH, these ducts would develop into fallopian tubes, uterus, and upper vagina.
Question 3: 3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -
- A. DHEA (Correct Answer)
- B. Progesterone
- C. Deoxycortisol
- D. Estradiol
Explanation: ***DHEA*** - The enzyme **3 beta-hydroxysteroid dehydrogenase (3β-HSD)** is crucial for converting **delta-5 steroids (pregnenolone, 17-OH-pregnenolone, and DHEA)** into **delta-4 steroids (progesterone, 17-OH-progesterone, and androstenedione)**. - A **deficiency** in 3β-HSD leads to the accumulation of its substrates, particularly **DHEA (dehydroepiandrosterone)** and **17-OH-pregnenolone**, due to the impaired conversion in the steroid synthesis pathway. - Among the accumulated substrates, **DHEA** has weak androgenic activity, making it clinically significant in this enzyme deficiency. *Progesterone* - **Progesterone** is a delta-4 steroid, which is synthesized from **pregnenolone** via the action of **3β-HSD**. - A deficiency in this enzyme would **decrease** the production of progesterone, not increase it, as the enzyme is required for its synthesis. *Deoxycortisol* - **Deoxycortisol (11-deoxycortisol)** is a precursor to cortisol, formed later in the adrenal steroid synthesis pathway from **17-hydroxyprogesterone**. - Its production would be **decreased** by a 3β-HSD deficiency, as the pathway is blocked upstream, reducing the formation of downstream products like cortisol and its precursors. *Estradiol* - **Estradiol** is an estrogen, synthesized from androgens (like testosterone) via the enzyme **aromatase**. - A deficiency in 3β-HSD would impair the production of androgens like androstenedione and testosterone, which are precursors for estradiol, thereby leading to a **decrease** in estradiol levels, not an increase.
Question 4: If blood supply to hypothalamus is interrupted through median eminence which hormone will have normal secretion?
- A. GH
- B. TSH
- C. Vasopressin (Correct Answer)
- D. Prolactin
Explanation: ***Vasopressin (ADH)*** - Vasopressin is synthesized in the **supraoptic and paraventricular nuclei** of the hypothalamus - It travels down **axons** (hypothalamic-hypophyseal tract) to the **posterior pituitary** where it is stored and released - Its secretion is **NOT dependent on the hypophyseal portal system** that passes through the median eminence - Interruption of the portal blood supply through the median eminence affects only the **anterior pituitary hormones** - Vasopressin secretion would remain **completely normal** as it bypasses the portal system entirely *Prolactin* - Prolactin is an anterior pituitary hormone under **tonic inhibition** by dopamine from the hypothalamus - Dopamine reaches the anterior pituitary via the **portal system through the median eminence** - Interruption of this blood supply would **block dopamine delivery**, resulting in **increased prolactin secretion** (not normal) - This is the classic "stalk effect" seen in pituitary stalk lesions *GH* - Growth Hormone requires **GHRH (Growth Hormone-Releasing Hormone)** stimulation from the hypothalamus - GHRH travels via the **portal system** to stimulate the anterior pituitary - Portal disruption prevents GHRH delivery → **Decreased GH secretion** *TSH* - Thyroid-Stimulating Hormone requires **TRH (Thyrotropin-Releasing Hormone)** stimulation - TRH travels via the **portal system** to the anterior pituitary - Portal disruption prevents TRH delivery → **Decreased TSH secretion**
Question 5: Which of the following statements about placental hormones is true?
- A. hCS plays a role in maternal glucose metabolism. (Correct Answer)
- B. hCG levels remain consistently high throughout pregnancy.
- C. The luteal-placental shift occurs around 10-12 weeks of gestation.
- D. Progesterone production requires fetal adrenal precursors.
Explanation: **Correct: *hCS plays a role in maternal glucose metabolism.*** - **Human chorionic somatomammotropin (hCS)**, also known as placental lactogen, has **anti-insulin effects** that reduce maternal glucose utilization. - This action diverts glucose to the fetus, helping to meet the growing **fetal energy demands**. *Incorrect: hCG levels remain consistently high throughout pregnancy.* - **hCG (human chorionic gonadotropin)** levels peak in the first trimester (around 8-10 weeks) and then **decline and plateau** at much lower levels for the remainder of the pregnancy. - Its primary role is to maintain the **corpus luteum** during early pregnancy. *Incorrect: The luteal-placental shift occurs around 10-12 weeks of gestation.* - The **luteal-placental shift**, where the placenta takes over progesterone production from the corpus luteum, occurs around **7-9 weeks of gestation**. - By 10-12 weeks, the placenta is already the primary producer of progesterone. *Incorrect: Progesterone production requires fetal adrenal precursors.* - **Progesterone** is synthesized by the placenta from **maternal cholesterol** without requiring fetal steroid precursors. - **Estrogen**, particularly **estriol**, on the other hand, relies on **fetal adrenal androgens** as precursors.
Question 6: Estrogen is secreted during pregnancy, mostly by which organ?
- A. Placenta (Correct Answer)
- B. Fetal ovary
- C. Pituitary
- D. Hypothalamus
Explanation: ***Placenta*** - During pregnancy, the **placenta** takes over the primary role of **estrogen production** from the ovaries, especially after the first trimester. - It synthesizes significant amounts of **estriol**, the main estrogen produced during pregnancy, using precursors from the fetal adrenal glands. *Fetal ovary* - The **fetal ovary** is not the primary source of estrogen synthesis during pregnancy. - While it has some hormonal activity, it does not produce the large quantities of estrogen needed to support the pregnancy. *Pituitary* - The **pituitary gland** produces hormones like **FSH and LH**, which regulate ovarian function, but it does not directly secrete estrogen itself. - Its role is supervisory, not secretory of sex steroids. *Hypothalamus* - The **hypothalamus** secretes **gonadotropin-releasing hormone (GnRH)**, which stimulates the pituitary, but it does not produce estrogen. - It is part of the central control system for reproductive hormones, not a direct estrogen secretor.
Question 7: What is the incorrect statement?
- A. MIS inhibits the formation of Mullerian duct
- B. WD form male internal genitalia
- C. Zygote is Bipotential at 8 weeks (Correct Answer)
- D. DHT is necessary for the development of external genitals
Explanation: ***Zygote is Bipotential at 8 weeks*** - A **zygote** is formed at conception and is the single-cell diploid organism, not bipotential at 8 weeks. - The **bipotential gonad** can develop into either testes or ovaries, and this stage of sexual differentiation occurs earlier in gestation, typically around the 6th to 7th week, before differentiating into male or female gonads, not at 8 weeks as an entire zygote. *MIS inhibits the formation of Mullerian duct* - **Müllerian Inhibiting Substance (MIS)**, also known as **Anti-Müllerian Hormone (AMH)**, is produced by the Sertoli cells of the developing testes [1]. - Its primary function is to cause the **regression of the Müllerian ducts**, which would otherwise develop into female internal reproductive structures (fallopian tubes, uterus, and upper vagina) [1]. *WD form male internal genitalia* - The **Wolffian ducts (WD)**, also known as mesonephric ducts, are precursors to male internal genitalia in the presence of testosterone [1]. - stimulated by **testosterone** produced by the Leydig cells of the fetal testes, they develop into the **epididymis, vas deferens, and seminal vesicles** [1]. *DHT is necessary for the development of external genitals* - **Dihydrotestosterone (DHT)**, a more potent form of testosterone, is crucial for the development of male external genitalia [1]. - The enzyme **5α-reductase** converts testosterone to DHT in target tissues, leading to the formation of the **penis, scrotum, and prostate** [1].
Question 8: Hypothalamus increases release of all hormones from the pituitary except ?
- A. ACTH
- B. TSH
- C. FSH
- D. Prolactin (Correct Answer)
Explanation: ***Prolactin*** - The hypothalamus primarily **inhibits prolactin release** from the anterior pituitary via **dopamine** (prolactin-inhibiting hormone). - All other hormones listed (ACTH, TSH, FSH/LH, GH) are stimulated by their respective hypothalamic releasing hormones. *ACTH* - The hypothalamus **increases ACTH release** by secreting **corticotropin-releasing hormone (CRH)**, which acts on the anterior pituitary. - CRH stimulates corticotrophs to synthesize and release ACTH, which then acts on the adrenal glands. *TSH* - The hypothalamus **increases TSH release** by secreting **thyrotropin-releasing hormone (TRH)**, which stimulates thyrotrophs in the anterior pituitary. - TRH also has a minor stimulatory effect on prolactin release, but its primary role is TSH stimulation. *FSH* - The hypothalamus **increases FSH release** (along with LH) by secreting **gonadotropin-releasing hormone (GnRH)** in a pulsatile manner. - GnRH stimulates gonadotrophs in the anterior pituitary to produce and secrete both FSH and LH.
Question 9: During early pregnancy (first trimester), estrogen is primarily secreted by which of the following structures?
- A. Hypothalamus
- B. Fetal ovary
- C. Pituitary
- D. Maternal ovary (Correct Answer)
Explanation: ***Maternal ovary*** - During **early pregnancy** (first 8-10 weeks), the **corpus luteum** in the maternal ovary is the primary source of **estrogen** and **progesterone**, essential for maintaining the pregnancy until the placenta matures. - The corpus luteum is maintained by **hCG** (human chorionic gonadotropin) secreted by the developing placenta. - After the first trimester, the placenta takes over as the main source of estrogen production. *Fetal ovary* - The **fetal ovary** does not contribute to estrogen production during pregnancy. - The fetal ovary remains undeveloped during gestation and only becomes active after birth during puberty. *Pituitary* - The **pituitary gland** produces **gonadotropins** (LH and FSH) which regulate hormone production, but does not directly secrete estrogen. - During pregnancy, pituitary gonadotropin secretion is actually suppressed due to high levels of placental hormones. *Hypothalamus* - The **hypothalamus** secretes **GnRH** (gonadotropin-releasing hormone) to regulate the pituitary, but does not produce estrogen. - Its role is in the hormonal control cascade, not in direct steroid hormone synthesis.
Question 10: Hypothyroidism in pregnancy is most likely associated with which of the following?
- A. Recurrent abortions
- B. Preeclampsia (Correct Answer)
- C. Preterm labour
- D. Polyhydramnios
Explanation: ***Preeclampsia*** - **Hypothyroidism** in pregnancy is strongly linked to an increased risk of **preeclampsia**, a serious condition characterized by **hypertension and proteinuria** after 20 weeks of gestation. - The exact mechanism is not fully understood, but thyroid hormones play a crucial role in maintaining **vascular tone and endothelial function**, which are disrupted in preeclampsia. - Studies show that both **overt and subclinical hypothyroidism** increase the risk of preeclampsia, making this the **most likely association** among the given options. *Recurrent abortions* - While uncontrolled **hypothyroidism** can increase the risk of **first-trimester miscarriage**, it is not typically cited as the most likely association for **recurrent abortions** compared to preeclampsia. - Other causes like **chromosomal abnormalities, uterine anomalies, or antiphospholipid syndrome** are more common for recurrent pregnancy loss. - Early detection and treatment with **levothyroxine** can reduce miscarriage risk. *Polyhydramnios* - **Polyhydramnios** (excess amniotic fluid) is more often associated with conditions like **gestational diabetes**, fetal anomalies (e.g., GI obstruction, neural tube defects), or multiple gestation. - **Hypothyroidism** is not a primary risk factor for **polyhydramnios**; fetal thyroid dysfunction (e.g., fetal hyperthyroidism due to maternal Graves' disease) is more relevant to amniotic fluid disorders. - Maternal hypothyroidism does not typically affect amniotic fluid volume. *Preterm labour* - Poorly controlled **hypothyroidism** can increase the risk of **preterm birth**, but **preeclampsia** is generally considered a more distinct and stronger association. - Other common causes of **preterm labor** include infections, uterine abnormalities, cervical insufficiency, and multiple gestations. - Adequate thyroid hormone replacement reduces obstetric complications including preterm delivery.
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