AFP is the a lot of abounding claret protein activate in the animal fetus. Claret levels abatement rapidly afterwards bearing but activate abbreviating prenatally starting at the end of the aboriginal trimester. Normal developed levels are usually accomplished by the age of 8 to 12 months. The action of AFP in developed bodies is unknown; however, in rodents it binds estradiol to anticipate the carriage of this hormone beyond the placenta to the fetus. The capital action of this is to anticipate the virilization of changeable fetuses. As animal AFP does not bind estrogen, its action in bodies is beneath clear.
The rodent AFP arrangement can be overridden with massive injections of estrogen, which beat the AFP arrangement and will masculinize the fetus. The masculinizing aftereffect of estrogens may assume counter-intuitive back estrogens are analytical for the able development of changeable accessory characteristics during puberty. However, this is not the case prenatally. Gonadal hormones from the testes, such as testosterone and antimullerian hormone are appropriate to could cause development of a phenotypic male. Without these hormones the fetus will advance into a phenotypic changeable even if genetically XY. Interestingly, the about-face of testosterone into estradiol by aromatase in abounding tissues may be an important footfall in masculinization of that tissue. Masculinization of the academician is anticipation to action both by about-face of testosterone into estradiol by aromatase, but aswell by de novo amalgam of estrogens aural the brain. Thus, AFP may assure the fetus from affectionate estradiol that would contrarily accept a masculinizing aftereffect on the fetus, but its exact role is still controversial.