The result of oogenesis is _____.

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: estrogen. Estrogen is responsible for thickening the lining of the uterus during the menstrual cycle in preparation for implantation of a fertilized egg. Follicle-stimulating hormone (FSH) stimulates the growth of ovarian follicles. Luteinizing hormone (LH) triggers ovulation. Progesterone helps maintain the uterine lining during the second half of the menstrual cycle. Estrogen plays a key role in the initial thickening of the uterine lining, making it the correct choice.

Correct Answer: C

Rationale: The correct answer is C: Zona pellucida. The ovum receives the sperm in the zona pellucida, which is a glycoprotein layer surrounding the oocyte. Sperm must first penetrate this layer to fertilize the egg. Choices A and B (Animal pole and Vegetal pole) refer to different regions of the egg and are not directly involved in sperm-egg interaction. Choice D (None of the above) is incorrect because the zona pellucida is indeed where the sperm interacts with the ovum during fertilization.

Correct Answer: C

Rationale: The correct answer is C: Spermatogonia. Spermatogonia are the male germ cells that undergo mitosis to produce more spermatogonia or differentiate into primary spermatocytes, which eventually develop into spermatozoa through meiosis. Sertoli cells (A) and Sustentacular cells (B) are somatic cells within the testes that support and nourish developing sperm cells, but they do not give rise to spermatozoa. Chief cells (D) are typically found in the stomach and are responsible for producing pepsinogen, unrelated to sperm production.

Correct Answer: A

Rationale: The correct answer is A: Labia majora. The labia majora are located anterior to the vagina and urethral openings, providing protection and support. The labia minora are internal to the labia majora. The mons pubis is the rounded mass of fatty tissue located over the pubic symphysis. Cervical sphincter is not a relevant anatomical structure in this context. Therefore, the labia majora is the correct choice based on its anatomical location and function.