Synthesis and release of gonadotropins and their subunits by long-term organ cultures of human fetal hypophyses.

From weeks 13 to 26 of fetal life human hypophyses disclosed a constant content of radioimmunoassayable FSH. Although present already before this period, LH content increased considerably at week 17, along with the appearance of free beta-LH. In long-term organ culture experiments such early differentiating pituitaries proved to be endowed with autonomous synthesis and release of FSH and of free alpha-subunit, while LH, beta-LH and TSH declined to very low levels within a few weeks. Supplementation of the medium with LH-RH (12 ng/ml) significantly increased FSH synthesis and release but was not sufficient to sustain production of beta-LH and LH. It is suggested that other factors than LH-RH are required for differentiation of beta-LH biosynthesis and thus for production of LH.