Testosterone is secreted by the following structures, EXCEPT:

Correct Answer: A

Rationale: The correct answer is A: prostate. Testosterone is primarily secreted by the testicular interstitial cells (Leydig cells) in the testes. The seminiferous tubules are responsible for spermatogenesis, not testosterone secretion. Straight tubules are involved in transporting sperm. The prostate gland produces prostatic fluid, not testosterone. Therefore, the prostate is not a structure that secretes testosterone.

Correct Answer: C

Rationale: The corpus luteum is formed from the ruptured follicle after ovulation. It secretes progesterone, which is crucial for preparing the uterus for implantation and maintaining early pregnancy. Progesterone helps thicken the uterine lining and supports embryo development. Estrogens are mainly produced by the ovaries, not the corpus luteum. Testosterone is primarily produced by the adrenal glands and testes, not the corpus luteum. Therefore, choice C is correct as it accurately describes the main hormone secreted by the corpus luteum.

Correct Answer: B

Rationale: The correct answer is B: the hypothalamus. The hypothalamus secretes gonadotropin-releasing hormone (GnRH) which stimulates the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which in turn regulate the secretion of ovarian hormones (estrogen and progesterone). The anterior pituitary secretes FSH and LH in response to GnRH from the hypothalamus. Therefore, the hypothalamus plays a crucial role in controlling the secretion of ovarian hormones. Choices A, C, and D are incorrect because the anterior pituitary releases FSH and LH but is not the primary controller, FSH is a hormone released by the anterior pituitary but is not the primary controller, and LH is released by the anterior pituitary but is not the primary controller of ovarian hormone secretion.

Correct Answer: D

Rationale: The correct answer is D because the placenta serves as a barrier between the maternal and fetal bloodstreams, allowing for the exchange of nutrients, oxygen, and waste products. This is crucial for the fetus's growth and development. Choice A is incorrect because the placenta does not physically surround the embryo. Choice B is incorrect as maternal and fetal blood do not mix due to the placental barrier. Choice C is incorrect as the heart of the fetus pumps blood, not the placenta.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.