Which of the following is responsible for secondary sex characteristics in females?

Correct Answer: A

Rationale: Estrogens are responsible for secondary sex characteristics in females as they promote breast development, regulate the menstrual cycle, and contribute to the distribution of body fat. Progesterone mainly prepares the uterus for pregnancy. Follicle-stimulating hormone (FSH) plays a role in the development of ovarian follicles and the maturation of eggs but does not directly influence female secondary sex characteristics.

Correct Answer: D

Rationale: The correct answer is D: sperm production. The spermatic cord houses the structures that support and transport sperm, including the vas deferens, blood vessels, nerves, and lymphatics. It does not produce testosterone (A), facilitate ovum fertilization (B), or contain the urethra (C). Sperm production occurs in the testes, while the spermatic cord provides the pathway for the sperm to travel from the testes to the urethra for ejaculation.

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: C

Rationale: The correct answer is C because a female actually ovulates only about 400-500 oocytes during her lifetime, not 2,000 to 4,000. This is due to the process of follicular atresia where many oocytes are lost before ovulation. Choice A is correct as females have a finite number of oocytes at birth. Choice B is correct as oogonia differentiate into primary oocytes during fetal development. Choice D is incorrect as typically only one oocyte is fertilized during each menstrual cycle.

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.