Endometrium

Correct Answer: B

Rationale: The correct answer is B: Stratum functionalis is shed during menstrual phase. The endometrium is composed of two layers - the stratum functionalis and the stratum basalis. The stratum functionalis is the layer that undergoes cyclic changes during the menstrual cycle, thickening and then shedding during menstruation. This process is essential for preparing the endometrium for potential implantation of a fertilized egg. Choice A is incorrect because the endometrium is actually lined by simple columnar epithelium with ciliated cells. Choice C is incorrect because the decidua is the name for the endometrium during pregnancy, but it is not specific to forming the decidua of the placenta. Choice D is incorrect because the arcuate artery is a branch of the uterine artery that runs along the myometrium, not penetrating the endometrium directly.

Correct Answer: D

Rationale: The correct answer is D: in the fifth month of pregnancy. The testes begin to descend from the abdomen into the scrotum during the fifth month of pregnancy. This process is crucial for proper development and function of the testes. Descending at this stage allows for the testes to be positioned outside the body, which is essential for sperm production as it requires a slightly lower temperature than the internal body temperature. Summary: A: at birth - Incorrect, as the descent of the testes occurs during fetal development, not at birth. B: two months after birth - Incorrect, as the descent happens during pregnancy, not after birth. C: two months prior to birth - Incorrect, as the descent occurs during pregnancy, not prior to birth.

Correct Answer: B

Rationale: The correct answer is B: scrotum. The scrotum is a male-specific structure that houses the testes, which are responsible for producing sperm. In females, there is no homologous structure that serves the same function as the scrotum. The other choices (A: penis, C: prostate, D: bulbourethral glands) have homologous structures in females (clitoris, Skene's glands, and Bartholin's glands, respectively). This differentiation is based on the embryological development of male and female reproductive structures.

Correct Answer: C

Rationale: The correct answer is C: one ovum. During oogenesis, a primary oocyte undergoes meiosis to produce one mature ovum and three polar bodies. The ovum contains the majority of the cytoplasm and organelles needed for fertilization. The other choices are incorrect because: A: one secondary oocyte - After meiosis I, the primary oocyte develops into one secondary oocyte and one polar body. B: two secondary oocytes - This is not a possible outcome of oogenesis as only one secondary oocyte is produced. D: four ootids - Ootids are the immediate products of meiosis II in oogenesis and are not the final mature gametes like the ovum.

Correct Answer: B

Rationale: The correct answer is B: vestibule. The vestibule is the space between the labia minora, housing the openings of the urethra and vagina. It is a specific anatomical term that describes this precise area. The other choices, A: vulva refers to the external female genitalia as a whole, C: vaginal orifice specifically denotes the opening of the vagina, and D: pudendal cleft is a term not commonly used in anatomy to describe this specific space. Therefore, B is the correct answer as it accurately describes the anatomical structure in question.