(WHO) Products and/or ingredients derived from tissues or secretions of animals susceptible to Transmissible Spongiform Encephalopathies (TSEs), primarily cattle’s Bovine Spongiform Encephalopathy (BSE). This definition applies to all substances or preparations obtained from such animals and to all substances or preparations where products obtained from such animals are included as active substances, excipients or adjuvants or have been used in production as raw or source materials, starting materials or reagents (e.g., bovine serum albumin; enzymes; culture media including those used to prepare working cell banks for medicinal products), or those utilized in the preparation/finishing of product contact surfaces in equipment or system components.