Light micrograph section through human spleen tissue showing evidence of hyaline degeneration of the splenic follicular arteries. Hyaline or amyloid-like material in the follicles is comprised of two components: the larger hyalinized and the fragmented material of damaged follicular artery in the central portion, surrounding peripherally by exuded plasma proteins, mainly fibrin. The degeneration of follicular arteries, vasculitis of the larger vessels and inflammation of the capsule, make the spleen susceptible to rupture.