Identification of human luteinizing hormone, follicle-stimulating hormone, luteinizing hormone beta-subunit and gonadotrophin alpha-subunit in foetal and adult pituitary glands.

Specific radioimmunoassays were used to assess the content of LH, FSH, the gonadotrophin alpha-subunit and the LH beta-subunit in four adult, 19 normal foetal pituitary glands (9-5--32 weeks of gestation) and a pituitary extract from an anencephalic foetus (36 weeks). The hormones and subunits were further identified by column chromatography on Sephadex G-100. All pituitary glands contained free alpha-subunit and intact LH but the alpha-subunit:LH ratio was significantly higher in the early foetal pituitaries (9-5--16 weeks) than in the four adult pituitaries. Only small or undetectable amounts of LH beta-subunit and 'undetectable' FSH were found in these early foetal pituitaries (9-5--11-5 weeks). The concentration of intact hormones or subunits in the pituitaries showed no significant sex difference in any of the groups. In contrast to these results, only alpha-subunit was detectable in the pituitary of the anencephalic foetus. For 14 early foetuses (age of gestation 10--16 weeks) the serum levels of LH-HCG, FSH, and alpha-subunit in the circulation were significantly higher than in 26 foetuses at term (37--41 weeks). On the basis of these results a theory for the development of the gonadotrophin secretion from the foetal pituitary gland is outlined.