Reticulin is a fibrous protein that forms the fine meshwork of reticular fibres, the delicate supporting scaffolding found in soft tissues such as the liver, spleen, lymph nodes, and around blood vessels and muscle fibres. Chemically it is closely related to collagen, and the fibres stain characteristically with silver, which is how histologists identify them. In meat science, reticulin is part of the connective tissue that influences tenderness: young animals have more of this fine, soluble network, which breaks down readily in cooking, while older animals accumulate tougher, cross-linked collagen. Understanding these connective tissue proteins helps explain why slow, moist cooking tenderises cuts rich in connective tissue and why the same treatment would ruin a tender steak.