Immunocompetence, mast cells and sexual behaviour

This paper reports a provocative and novel observation. Specifically, we have shown that in Ring Doves Streptopelia roseogrisea , following a brief period of courtship, cells of the immune system–mast cells–appear in the brain. This is surprising in that it has long been thought that the blood‐brain barrier prevents the movement of blood‐borne cells into the parenchyma (neural tissue) of the brain. The conditions under which these cells appear, their chemical and ultrastructural features and their potential in neuroendocrine signalling functions are discussed. The significance of these cells for the expression of behaviour and their specific role in the medial habenula (the brain area to which they migrate) remain to be explored. While our research has focused on a domesticated, laboratory bird species, the relationship between sexual behaviour and immunocompetence has long been of interest in field work and in studies on the evolution of sexual behaviour. It is hoped that this work, now in its infancy, will bridge field and laboratory, as well as providing a forum for integrating mechanistic and evolutionary concepts in neuro‐immuno‐endocrinology.