Contain longitudinal smooth muscle, vasa vasorum

Correct Answer: C

Rationale: Tunica adventitia contains longitudinal smooth muscle and vasa vasorum in larger lymphatic vessels; stratum basale is epithelial.

Correct Answer: D

Rationale: Thymus stroma has a thin C.T. capsule , incomplete trabeculae , and reticular C.T. ; it does not have a thick capsule (D is incorrect).

Correct Answer: B

Rationale: Billroth cords in spleen red pulp are infiltrated with blood and lymphoid cells ; they're not in lymph nodes or between follicles , and lack central arterioles .

Correct Answer: C

Rationale: Th17 responses recruit neutrophils to fight extracellular pathogens; monocytes and eosinophils are less characteristic.

Correct Answer: C

Rationale: MHC II binds longer peptides due to open ends ; HLA-D regions encode them , they're stable , and only on APCs .