Male sex hormone. Polarised light micrograph of crystals of 5-alpha- dihydrotestosterone, also known as DHT. DHT is the most potent of the naturally-occurring androgens, the class of hormones associated with the development of male reproductive organs and secondary sex characteristics. DHT is secreted in the testes, and is made by the action of an enzyme, 5-alpha transcriptase, on testosterone. A deficiency of this enzyme may lead to a variety of syndromes including hermaphroditism. These may be reduced by hormone replacement therapy. Magnification x8 at 35mm size.