Which cells are key to type II hypersensitivity?

Correct Answer: B

Rationale: B cells produce antibodies for type II; T cells are type IV, mast cells are type I, neutrophils are innate.

Correct Answer: A

Rationale: The thymic medulla is supported by epithelioreticular cells forming a reticular framework.

Correct Answer: D

Rationale: Bicuspid valves in lymphatic vessels ensure unidirectional lymph flow; tricuspid, aortic, and pulmonary valves are in the heart.

Correct Answer: C

Rationale: The spleen's capsule contains vessels, nerves, muscle , dense C.T. , and trabeculae ; it's thick at the hilum, not thin (C is incorrect).

Correct Answer: B

Rationale: Thymus is located in the thoracic cavity behind the sternum.