The company involved with Alder Hey was Aventis Pasteur, a leading vaccination research firm based in Lyons. An Alder Hey spokesman said: "In some cases to carry out complex heart surgery it is necessary for the thymus gland to be removed. The hospital can confirm that for a brief period between 1991 and 1993 these were made available to a pharmaceutical company for research, and we are aware that during that period contributions were made to the trust's cardiac department."