A specific, high-affinity, limited-capacity estrogen binding component in the cytosol of human fetal pituitary and brain tissues.

A macromoleclar component which binds 3H-estradiol with high affinity and limited capacity is present in the 150,000 x g supernatant fraction of pituitary, hypothalamus, cortex, and limbic system of both male and female human fetwses. 17 beta-estradiol and 17alpha-ethinylestradiol effectively compete with 3H-estradiol for binding sites while testosterone, dihydrotes-tosterone, and cortisol do not. The binding component is different from sexhormone-binding-globulin. It is present in these tissues in relatively large amounts and it is tentatively identified as an estrogen recptor.