Evidence for a histaminergic system in the human testis

The complete lack of information about mast cells as a source of histamine and potential target cells for histamine in human testes prompted us to investigate these issues in testes of fertile and infertile patients using a combination of laser microdissection, reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemistry. We show for the first time the expression of the rate-limiting enzyme in histamine synthesis-histidine decarboxylase-by human testicular mast cells and the expression of the histamine (H) receptors 1 (H1) and 2 (H2) by germinal, interstitial, and peritubular cells in the testes of fertile and infertile patients.