LOCALIZATION OF ANTERIOR PITUITARY HORMONES ON EPON SECTIONS BY PEROXIDASE-LABELED ANTIBODY METHOD-LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS

Abstract

In order to improve immunohistochemical staining of standard paraffin sections, and to explore the possibility of a single procedure for both light and electron microscopic observations, the plastic embedding method was investigated. The rat pituitary glands fixed with Acrolein and embedded in Epon showed excellent light microscopic staining with the peroxidase-labeled antibody method on 1μm sections cut by a glass knife. Antigenicity of both peptide hormones (ACTH, prolactin, GH) and glycoprotein hormone (LH) was preserved even after osmification. Compared to the Zamboni fixed or Bouin fixed paraffin sections, this method resulted in much more sharply defined and better preserved positively stained cells. Furthermore, this method is especially useful in the neoplastic condition, i.e. pituitary adenomas, where fixation is extremely difficult.Ultrastructural observations of cells positively stained with this method revealed the presence of the immunoreactive hormones on the secretory granules and probably on the adjacent membranous structures. In considering these advantages, it seems probable that this method will replace paraffin sections in localizing pituitary hormones, and possibly other peptide or glycoprotein hormones with the peroxidase-labeled antibody method.