DENNIS KUNKEL MICROSCOPY / SCIENCE PHOTO LIBRARY DENNIS KUNKEL MICROSCOPY / SCIENCE PHOTO LIBRARY
Light micrograph (LM) of Testosterone crystals. Testosterone is a steroid hormone from the androgen group. It is the principal male sex hormone and the original anabolic steroid. Like other steroid hormones testosterone is derived from cholesterol. The largest amounts of testosterone are produced by the testes, but it is also synthesized in smaller quantities by the theca cells of the ovaries, the zona reticulosa of the adrenal cortex, and the placenta. Substantial amounts of the testosterone in women are also produced from estradiol by reverse aromatization in the liver, adipose cells, and other peripheral tissues. In the testes testosterone is produced by the Leydig cells. Due to dual function of the male gonad, testosterone directly influences spermatogenesis. Magnification: x25 when shortest axis printed at 25 millimetres.
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