This MAb is highly specific to testosterone. Its affinity constant for testosterone is ~1010 M-1. In competitive binding immunoassay, it reacts with testosterone 100%, 11-beta-hydroxy testosterone 3.3%, 17-alpha-methyl testosterone <0.1%, 5-alpha DHT 0.8%, estradiol <0.1% and progesterone <0.1%. Testosterone, a steroid hormone from the androgen group, is derived from cholesterol. Testosterone is primarily secreted in the testes, but the ovaries and adrenal glands also produce smaller amounts. It is the principal male sex hormone and is responsible for the maturation of sex organs and the development of male secondary sex characteristics. The hormone is also involved in the growth of [muscle biology research] and increases bone density and maturation. It functions by activating the androgen receptor and converting to estradiol and activation of estrogen receptors. Testosterone has been employed therapeutically to [research relevance to related conditions], height growth and bone marrow stimulation. Anti-testosterone antibody may also prove useful in identification of testicular tumors arising from interstitial cells. Primary antibodies are available purified, or with a selection of fluorescent CF® Dyes and other labels. CF® Dyes offer exceptional brightness and photostability. Note: Conjugates of blue fluorescent dyes like CF®405S and CF®405M are not recommended for detecting low abundance targets, because blue dyes have lower fluorescence and can give higher non-specific background than other dye colors.