From fertilization to week 8 of proliferative phase of the uterine pregnancy, the conceptus is called (menstrual) cycle? ________.

Correct Answer: D

Rationale: The correct answer is D: an embryo. From fertilization to week 8 of the proliferative phase of uterine pregnancy, the conceptus is referred to as an embryo. This is because during this period, the fertilized egg undergoes rapid cell division and differentiation, leading to the formation of distinct embryonic structures and the beginning of organ development. The term "fetus" is used after the embryonic stage, typically from week 9 onwards. Choices A and C, estrogens and progesterones respectively, are hormones involved in regulating the menstrual cycle and maintaining pregnancy but are not terms used to describe the developing conceptus itself during this specific timeframe.

Correct Answer: A

Rationale: The correct answer is A because ejaculation is primarily controlled by the sympathetic nervous system, not the para-sympathetic system. The sympathetic nervous system triggers the contraction of smooth muscles to allow for ejaculation. Choice B is incorrect because ejaculation is not a result of summation of synaptic potentials, but rather a coordinated response. Choice C is incorrect because semen is expelled by rhythmic contractions of the pelvic floor muscles, not the urethral smooth muscle. Choice D is incorrect because ejaculation involves the discharge of sperm, seminal vesicle, prostatic secretions, and other fluids from the reproductive system.

Correct Answer: C

Rationale: Rationale: C is correct because Leydig cells in the testes secrete testosterone, which is essential for stimulating spermatogenesis in the Sertoli cells. Testosterone plays a crucial role in the development and maturation of sperm. A is incorrect because follicle stimulating hormone is secreted by the pituitary gland, not the hypothalamus. B is incorrect because luteinizing hormone is secreted by the pituitary gland, not the hypothalamus. D is incorrect because Leydig cells primarily secrete testosterone, not inhibin.

Correct Answer: A

Rationale: The correct answer is A: Uterus. The uterus is a thick, muscular organ located in the lower abdomen where a developing baby grows during pregnancy. It can expand significantly to accommodate the growth of the fetus. The ovaries (B) are responsible for producing eggs, not for accommodating a developing baby. The vulva (C) refers to the external female genitalia, not the organ that supports pregnancy. The breast (D) is responsible for producing milk after childbirth, not for housing a developing baby.

Correct Answer: D

Rationale: The correct answer is D: vestibular bulbs. The male reproductive system consists of the prostate, testicles, and spermatic ducts, all essential for the production, storage, and transportation of sperm. Vestibular bulbs are actually part of the female reproductive system, involved in sexual arousal, and not found in the male reproductive system. Therefore, it is the only structure listed that is not a part of the male reproductive system.