Ectoderm, mesoderm, and endoderm are three tissue layers that are formed during _____________ stage.

Correct Answer: C

Rationale: The correct answer is C: gastrula. During the gastrula stage of embryonic development, the blastula undergoes a process called gastrulation, where the three primary germ layers - ectoderm, mesoderm, and endoderm - are formed. The ectoderm gives rise to the nervous system and skin, the mesoderm forms muscles and organs, and the endoderm develops into the lining of the digestive tract and respiratory system. Morula (A) is an earlier stage where the zygote divides into multiple cells. Blastula (B) is the stage before gastrula where a hollow ball of cells is formed. Neurula (D) is a stage specific to vertebrate embryos where the neural tube begins to form.

Correct Answer: B

Rationale: The correct answer is B: Increased size of the uterus. In a 72-year-old woman, an increased size of the uterus can indicate potential issues such as fibroids or endometrial hyperplasia, which may require further investigation. Thinning of pubic hair (A) is a common age-related change. Decreased size of the clitoris (C) and loss of tone of the pelvic ligaments (D) can also occur with aging but are not typically concerning findings during a routine physical exam in this age group.

Correct Answer: C

Rationale: The correct answer is C: ampulla. The ampulla is a dilated portion at the end of the vas deferens where it joins with the duct of the seminal vesicle to form the ejaculatory duct. This structure serves as a storage and mixing area for sperm and seminal fluid before ejaculation. The other choices, A: ductus deferens, is another name for the vas deferens itself; B: seminal vesicle is a gland that produces seminal fluid but is not the dilated sac at the end of the vas deferens; D: ejaculatory duct is formed by the union of the vas deferens and the duct of the seminal vesicle, it is not the dilated sac itself.

Correct Answer: A

Rationale: The correct answer is A, loss of body hair. Testosterone is responsible for thickening of the larynx, anabolism of skeletal muscle, and thickening of bones. It promotes growth and development of male secondary sexual characteristics, such as increased body hair. Therefore, loss of body hair is not a function of testosterone. Choice B, thickening of the larynx, is correct because testosterone contributes to the deepening of the voice by thickening the vocal cords. Choice C, anabolism of skeletal muscle, is correct as testosterone enhances protein synthesis in muscles, leading to muscle growth. Choice D, thickening of bones, is correct because testosterone promotes bone growth and mineralization.

Correct Answer: A

Rationale: The correct answer is A: perimetrium. The perimetrium is the outer serosal layer of the uterus, providing protection and support. The other choices are incorrect: B. cervix is the lower portion of the uterus, C. endometrium is the inner lining where implantation occurs, and D. myometrium is the middle muscular layer of the uterus. The perimetrium is the outermost layer, making it the correct choice.