Figure 2a. Specific actions of Testosterone (T). T is synthesized in the testis under control of luteinizing hormone (LH) from the pituitary . After entering the target cells (in the hypothalamus, pituitary, testis and wolffian duct) T is directly bound to the androgen receptor (AR) and the complex T-AR binds to specific DNA sequences and regulates gene transcription, which can result in negative feedback regulation of gonadotrophin synthesis and secretion, in initiation and regulation of spermatogenesis and in differentiation and development of the wolffian duct.