With regard to secondary lymphatic nodules: They are characterised by the presence of germinal centres.

Correct Answer: A

Rationale: Germinal centers are a hallmark of secondary lymphatic nodules, where B-cell proliferation and differentiation occur.

Correct Answer: A

Rationale: Lymph nodes are bean-shaped with a capsule; spleen is larger and oval, tonsils lack a full capsule, liver is not lymphatic.

Correct Answer: B

Rationale: Blood sinusoids facilitate blood passage from spleen to bloodstream.

Correct Answer: C

Rationale: Epithelial reticular cells in the thymus originate from endoderm (pharyngeal pouches).

Correct Answer: C

Rationale: Blood-thymic barrier includes a perivascular space with macrophages ; endothelium is continuous , basement membrane thick , no plasma cells .