FIGURE 1

Somatotroph hyperplasia, Case 1. A, The secretory granules of cells having features of lactotrophs are labeled for both growth hormone (GH) and prolactin (PRL). One cell (right upper) is labeled for GH only, 14,200×. B, Mammosomatotroph (left) is heavily labeled for both GH and PRL, whereas a somatotroph (right) carries only the GH label, 24,000×. There is only light, nonspecific background labeling outside the secretory granules. Immunoelectron microscopy using double-immunogold labeling was used. GH: 10 nm, PRL: 20 nm.