: Argyrophilic fibre are reticular connective tissue fibres. Reticulin fibres have a strong affinity for silver salts (argyrophilia) and are PAS positive /probably due to associated proteoglycans and glycoproteins. When reticulin fibres retreated with silver salts they reduce the silver salts creating silver metal deposits that stains the fibres black. Reticulin fibres are slender bundles of collagen fibrils, 0.2 to 0.5 mm in diameter, that form a delicate fibrillary network in hematopoietic organs 1 and many other tissues. Reticulin fibres are composed mainly of collagen type III with small quantities of other types of collagen, glycoproteins and proteoglycans.