Umbilical cord contains _________

Correct Answer: B

Rationale: The correct answer is B: Cord blood stem cells. Umbilical cord blood contains stem cells that are collected from the blood in the umbilical cord and placenta after a baby is born. These stem cells are known as cord blood stem cells, which are multipotent and have the potential to develop into various types of cells in the body. Pluripotent stem cells (choice A) refer to stem cells that can differentiate into almost any cell type, which is not specifically present in the umbilical cord. Blood stem cells (choice C) are found in bone marrow and are responsible for producing blood cells, but they are not the primary type of stem cells found in umbilical cord blood. Choice D is incorrect because umbilical cord blood indeed contains cord blood stem cells.

Correct Answer: B

Rationale: The correct answer is B: Testosterone. Testosterone promotes the final step of spermatogenesis, which is the maturation of spermatids into spermatozoa. Testosterone is essential for the development and maintenance of male reproductive tissues and secondary sexual characteristics. Choice A, Relaxin, is not involved in spermatogenesis. Choice C, Inhibin, regulates FSH secretion but does not directly promote the final step of spermatogenesis. Choice D, Estrogen, is a female sex hormone and not directly involved in spermatogenesis.

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: Mastopexy. This surgical procedure involves lifting and fixing a pendulous breast to the chest wall to achieve a more youthful and firmer appearance. It does not involve removal of breast tissue like in mastectomy (B) or creation of a new breast mound like in mastostomy (A). Mesopexy (D) is not a recognized surgical procedure for breast lifting.

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.