Androgen and oestrogen receptor status of the human appendix testis

Since the human appendix testis is a Mullerian duct derivative it has been theorised that rising oestrogen levels in puberty result in enlargement of this organ and consequent predisposition to torsion. This study sought to establish the presence or absence of both androgen and oestrogen receptors in the human appendix testis. Bilateral appendix testis specimens surgically excised from ten patients undergoing scrotal exploration for acute scrotum were stained immunohistochemically for androgen and oestrogen receptors. These were examined by light microscopy. The human appendix testis was found to express both oestrogen and androgen receptors. Marked regional variation of androgen and oestrogen receptor positivity was demonstrated. The surface epithelium and some stromal cells were androgen receptor positive, whereas oestrogen receptors were confined to ductular invaginations, gland-like structures and some stromal cells. Rising levels of androgens and oestrogens in pubertal boys may account for enlargement and the predisposition of the human appendix testis for torsion since this structure contains receptors for both.