ABSTRACT
Testosterone has the standard four-ring steroid structure with two additional methyl groups, making it a 19 carbon steroid. In the body it is synthesised in the testes, ovaries and adrenal cortex. An isomer, epitestosterone, is always synthesised at the same time in the ratio 12:1, testosterone:epitestosterone. Some testosterone is converted into oestradiol in the body by a process called aromatisation. This only becomes of interest when excess amounts of testosterone are present. Under these conditions enough oestradiol can be produced to cause feminising effects in males (see below).
