Regarding the lymphatic capillaries, choose the correct statement:

Correct Answer: A

Rationale: Lymphatic capillaries are made of a single endothelial layer ; they are more permeable, lack tight junctions, and have no pericytes.

Correct Answer: B

Rationale: IFN-γ activates macrophages by signaling invader presence ; it enhances killing (A indirectly), doesn't directly increase lysosomes , and TNF production is a result.

Correct Answer: B

Rationale: Short TCR tails can't signal activation ; CD3 compensates; antigen recognition and co-receptor binding are intact.

Correct Answer: C

Rationale: High self-affinity T cells are removed by negative selection ; anergy is peripheral, activation and positive selection retain cells.

Correct Answer: B

Rationale: The thoracic duct empties into the left subclavian vein at the jugular-subclavian junction.