Quantitative analysis of immunoreactive human growth hormone (HGH) in the secretory granules of normal pituitary glands and hgh-producing pituitary adenomas. An immunoelectron microscopic study using the protein A-gold (PAG) technique.

We applied the protein A-gold (PAG) technique to two normal human pituitary glands and three samples of hGH-producing pituitary adenoma in order to demonstrate immunoreactive hGH at the ultrastructural level. Ultrathin mirror sections immunostained for hGH were observed by electron microscopy and the numbers of immunoreactive gold particles were calculated. The numbers of gold particles of the same secretory granule shared by the mirror sections showed counts which were approximately the same. Thus, assuming that the influence on the hGH antigenicity of the tissue treatment and conditions of immunostaining should be the same at all points on the ultrathin sections, the numbers of gold particles were considered to be a quantitative indicator of the amount of hGH antigen on the secretory granules of sections processed under the same conditions. The numbers of gold particles per micron2 of cut surface of secretory granules in hGH-producing adenoma cells were statistically lower than those of hGH-positive cells from normal pituitary glands, suggesting endocrinological derangement of the tumor cells together with morphological immaturity in their secretory granules and other organelles.