Figure 1.

−40hGH transgene expression in mouse pituitary was restricted to somatotrope cells. (A) Representative section of a pituitary from a −40hGH (F) adult transgenic mouse. A subset of cells stained positively with mAb9, which is specific for hGH (brown cytoplasmic stain). (B) A nontransgenic mouse pituitary stained with mAb9 was negative, indicating the specificity of mAb9 for hGH. (C) −40hGH pituitary cells were doubly immunostained with mAb9 and anti-Pit-1 (blue-gray nuclear stain). mAb9 positivity (brown) was detected only in the cytoplasm of cells that also exhibited nuclear staining for Pit-1 (white arrow). Pit-1-positive cells unreactive with mAb9 represent lactotrope or thyrotrope populations (black, barbed arrow). Other cells were negative for both stains (solid black arrow). (D) Double stain of the −40hGH pituitary with mAb9 and anti-rGH colocalized mGH (brown) and hGH using mAb9 (charcoal black) in the same cells, resulting in a dirty brown appearance. (E) Representative section of a pituitary from a −0.5hGH adult transgenic mouse. The weakly staining mAb-positive cells (brown cytoplasmic stain) were widely and nonspecifically distributed throughout the anterior (PA, pars anterior) and intermediate (PI, pars intermedia) lobes of the pituitary. The higher-power (×170) Inset shows a double stain for mGH and hGH; the reactivity showed distinct mGH-positive somatotropes (charcoal black; white arrows) in contrast to the diffuse and generalized positivity for hGH (mAb9; brown) visible in most of the cells. (F) The hGH gene cluster, pituitary HS, and the hGH-N transgenes used in these studies. (A, B, D, and E were counterstained with hematoxylin; C had no counterstain. A, B, and E, ×70; C and D ×170.)