Abstract
A method of pituitary-TSH (Thyroid-stimulating hormone) purification is applied to normal human placenta and allows the detection of a chorionic thyroid stimulating factor (Human-chorionic thyroid-stimulating factor, H.C. TSF). Immunological studies reveal a rather close but not complete antigenic relationship between human pituitary-TSH and H.C. TSF. Immunological data and the sustained biological effect into mice (test animal) suggest that H.C. TSF would possess some differences in structures when compared to human pituitary TSH.