Abstract: This process of preparation consists in subjecting said placental tissue after pressing, grinding and washing in a neutral and acid medium to a treatment in alkaline medium at a temperature less than or equal to 10.degree. C. and in then subjecting the portions of collagen solubilized during this treatment, as well as the collagen solutions resulting from an eventual subsequent treatment for the solubilization, at least partial, of the insoluble residue, to purification by chromatography on an anion exchange resin, at a temperature less than or equal to 10.degree. C., followed with fractional precipitation of the collagens by salts in acid medium.The human collagenous materials obtained can be used as biomaterials in biotechnology and in pharmacy and are perfectly immunologically innocuous for the human species.

Abstract: New and highly stable preparations containing collagen in association with mucopolysaccharides are obtained by combining a homogeneous gel or solution of crosslinked or decrosslinked collagen, and a solution of CSA or CSC, and bringing the pH to 7.