Developed and produced by http://www.MechanismsinMedicine.com Animation Description: This animation represents a visual interpretation of the production of testosterone and is not indicative of clinical effectiveness. The hypothalamus releases gonadotropin-releasing hormone (GnRH) in pulses every 60 to 90 minutes to stimulate the pulsatile release of luteinizing hormone (LH) from the pituitary gland into the bloodstream. LH binds the LH receptor on the Leydig cells of the testes. Binding initiates a cascade of events which include the conversion of cholesterol (depicted as LDL here) to pregnenolone followed by a series of reactions, which convert pregnenolone to testosterone. Testosterone, secreted by the testes, diffuses into the peripheral circulation to be carried to target tissues. In liver, muscle and adipose tissue, testosterone binds directly to its androgen receptor (AR) to exert its biological effect. In skin, hair, the prostate gland and gonadal tissue, testosterone must be converted to dihydrotestosterone (DHT) by 5-alpha-reductase in order to bind the androgen receptor. In bone and brain, testosterone is converted by aromatization to estradiol (E2), which binds the estrogen receptor (E2R) to carry out its effects. There is an accompanying accredited online resource, http://www.ManagingTD.ca that contains the learning materials, as well as videos, animations & an interactive algorithm.