9 March 1989 5.73 Guidelines and a questionnaire relating to medical devices were sent on 17 March 1989, under cover of a letter signed by Miss Duncan, to 328 recipients drawn from the membership of the MRS in relation to sterile medical devices and surgical products. As a purely precautionary measure, we have developed the enclosed guidelines for manufacturers of medical devices who use bovine, or other animal materials, either as a component or in the production process. The guidance represents 'best practice' for future manufacture and outlines the steps which should now be taken to implement it. It is realised that this guidance may not be fully applicable in all circumstances and it will be further developed in the light of experience. 11 5.74 Recipients were asked to respond by 1 May 1989.
Biological heart valves.
Orthopaedic implants such as tendons, bone grafts etc. Single use sterile devices that use such animal derivatives as heparin and gelatin in, for example, coatings. Any other implantable products or products which come into contact with blood or the lymphatic system and which utilise materials of bovine origin. Tissues to be excluded Brain or neural tissue, spleen, thymus and other lymphoid tissue, placental tissue or cell cultures of bovine origin should not be used in manufacture. Bovine material should come from animals, taken from a closed herd in the female line since 1980, in which no animal has been clinically suspected of having BSE, and which has not been fed rations containing ruminant derived proteins during that period.