20 .The normal microscopic appearance of the adenohypophysis is shown here. The adenohypophysis contains three major cell types: acidophils, basophils, and chromophobes. The staining is variable, and to properly identify specific hormone secretion, immunohistochemical staining is necessary. A simplistic classification is as follows: The pink acidophils secrete growth hormone (GH) and prolactin (PRL) The dark purple basophils secrete corticotrophin (ACTH), thyroid stimulating hormone (TSH), and gonadotrophins follicle stimulating   hormone-luteinizing hormone (FSH and LH) The pale staining chromophobes have few cytoplasmic granules, but may have secretory activity.