Immunocytochemical and morphometric evidence of the existence of different cellular populations reactive to r-GHRH in the rat pituitary gland.

In order to characterize the pituitary cells re a ctive for r-GRF in the adult rat, an immunocytochemicaI and morphometric study was made of the cells immunopositive for r-GHRH and those immunopositive for GH and for GHRH using a double labelling method. The existence of two populations of r- G R F - i m m u n o reactive cells was observed; one of these was only stained with specific serum against r-GRF and the other was immunopositively stained for GH and for r- G H R H . Morphometrically, in both sexes the GHi m m u n o reactive cells were seen to have a cellular size that was significantly larger (p