During fetal development which cells give rise to primary oocytes?

Correct Answer: C

Rationale: The correct answer is C: Oogonia. Oogonia are the cells that give rise to primary oocytes during fetal development. Oogonia undergo mitosis to produce primary oocytes, which then enter meiosis I to form secondary oocytes. Spermatogonia (A) are male germ cells that develop into sperm, not oocytes. Secondary oocytes (B) are formed from primary oocytes in the ovary after meiosis I completion. Granulosa cells (D) are somatic cells in the ovary that support oocyte development but do not give rise to oocytes themselves.

Correct Answer: C

Rationale: The correct answer is C: Placenta. The placenta is a vascular organ that develops within the uterine wall during pregnancy. It serves as a connection between the mother and fetus for nutrient and waste exchange. The amnion (A) and chorion (B) are fetal membranes, not vascular organs, and the endometrium (D) is the inner lining of the uterus where the placenta attaches.

Correct Answer: C

Rationale: The correct answer is C: Myometrium. The myometrium is the middle layer of the uterus composed of smooth muscle tissue responsible for uterine contractions during childbirth. The endometrium (A) is the innermost layer responsible for menstruation and implantation. Ectometrium (B) is not a correct term. Perimetrium (D) is the outermost layer of the uterus. Therefore, C is the correct choice as it accurately represents the middle layer of the uterus.

Correct Answer: B

Rationale: The correct answer is B: Labia. The term "labia" refers to the lips of the vagina. It is the plural form of "labium." "Labial" (A) refers to anything related to the lips, "Labrum" (C) refers to a rim or edge, and "Labor" (D) refers to the process of childbirth. Therefore, B is correct as it specifically refers to the structure being described.

Correct Answer: B

Rationale: The correct answer is B: Sphenoid bone. The sphenoid bone is bat-shaped and forms part of the base of the skull. It is located in the middle of the skull, helping to connect the cranial bones. The other choices, A: Ethmoid bone, C: Parietal bone, and D: Occipital bone, do not match the description of a bat-shaped bone at the base of the skull. The ethmoid bone is located between the eyes, the parietal bone forms the top and sides of the skull, and the occipital bone forms the back and base of the skull. Therefore, B is the correct answer based on the specific description given in the question.