The thymus and its role

The thymus was first clearly described as long ago as 1522, by Berengario in his Isagoge, but its physiological significance has only very recently become apparent. It is now clear that this small organ plays a key role in organising the immunological defence mechanisms of the body. This article reviews current ideas in the action of the thymus, and the possible repercussions in medicine and our clearer understanding of its function.