Immunohistochemical localization of pituitary gonadotrophins and gonadal steroids confirms the 'two-cell, two-gonadotrophin' hypothesis of steroidogenesis in the human ovary.

Ovaries from 37 women with normal menstrual cycles were analysed for localization of pituitary gonadotrophins and gonadal steroids using an immunohistochemical method. In the follicular phase, FSH and oestradiol-17 beta localized in the granulosa layer, and LH, progesterone and testosterone localized in the internal thecal layer. In the luteal phase, gonadotrophins and steroids localized in luteal cells. Particularly in the early luteal phase, FSH and oestradiol-17 beta localized in large luteal cells, and LH, progesterone and testosterone localized in small luteal cells. The results of the present immunohistochemical analysis confirm the two-cell, two-gonadotrophin hypothesis of steroidogenesis in the human ovary.