to test how f gene expression affects the gonadotrophin-releasing hormone ( gnrh ) concentration in hypothalamic or extrahypothalamic regions of the brain , gnrh was measured by radioimmunoassay in acetic acid extracts of various brain tissues from booroola ewes which were homozygous ( ff ) , heterozygous ( f+ ) or non-carriers ( ++ ) of the f gene .
C0020663
hypothalamic
C0023610
gnrh