Which of the following components of the fetoplacental (endocrine) unit is similar to thyroid stimulating hormone (TSH) and stimulates T4 secretion by the maternal thyroid?

Correct Answer: A

Rationale: Rationale: 1. Human chorionic gonadotropin (hCG) acts like TSH, stimulating T4 secretion by the maternal thyroid. 2. hCG is produced by the placenta and has a similar structure and function to TSH. 3. hCG binds to the TSH receptor on the thyroid gland, triggering T4 release. 4. Other options do not specifically target the thyroid gland for T4 secretion. Summary: A: hCG mimics TSH and directly stimulates T4 release. B: hCS, hPL - involved in placental growth and lactation, not thyroid stimulation. C: IGF I and II - growth factors, not directly related to thyroid function. D: EGF - promotes cell growth and differentiation, not linked to thyroid hormone secretion.

Correct Answer: D

Rationale: Progesterone is the correct answer because it is the hormone that works with estrogen to prepare the endometrium for implantation of a fertilized egg. Progesterone helps thicken the endometrium, creating a favorable environment for implantation. LH and FSH are involved in ovulation and follicle development, not endometrial preparation. ADH is antidiuretic hormone, which regulates water balance in the body, not related to endometrial preparation.

Correct Answer: C

Rationale: Rationale: 1. The correct answer is C: Liver cells. The liver is the principal site of estrogen synthesis in the male. 2. Liver cells contain the enzyme aromatase, which converts androgens into estrogens. 3. Estrogen plays a crucial role in maintaining normal reproductive function in males. 4. Leydig cells (Choice A) are responsible for testosterone production, not estrogen synthesis. 5. Osteoblasts (Choice B) are bone cells involved in bone formation, not estrogen synthesis. 6. Prostate cells (Choice D) are involved in prostate function, not estrogen synthesis.

Correct Answer: B

Rationale: Correct Answer: B - Her luteinizing hormone secretion rate will be totally suppressed Rationale: 1. The tumor secretes large amounts of estrogen, which can lead to negative feedback on the hypothalamus and pituitary gland. 2. Luteinizing hormone (LH) is crucial for ovulation and normal menstrual cycles. 3. High estrogen levels can suppress LH secretion, disrupting ovulation and menstrual cycles. Summary of other choices: A: Progesterone levels may actually be elevated due to the tumor-induced high estrogen levels. C: The disruption of LH secretion can lead to abnormal menstrual cycles. D: High estrogen levels can lead to bone loss due to inhibition of bone formation and increased bone resorption.

Correct Answer: B

Rationale: The correct answer is B: The fetal liver stores enough iron to meet the infant’s needs until the third month. During pregnancy, the fetus accumulates iron stores in the liver from the mother, which can sustain the infant's iron needs for the first few months of life. This stored iron is gradually utilized by the infant as the maternal iron supply diminishes post-birth. Explanation of why the other choices are incorrect: A: Growth of the infant does require iron even in the early months for various metabolic processes and functions. C: Synthesis of new red blood cells starts shortly after birth, not necessarily after 3 months. D: Myoglobin is not directly related to iron supplementation needs in infants and is unrelated to the timing of iron supplementation requirements.