Fig 2: Immunohistochemical findings of GLP-1-positive cells in the chicken ileum. (a) A section stained with the PrLSB procedure and counterstained with Mayer’s hematoxylin. (b) A section stained with the PrCG procedure. The immunoreactive cells are distributed in the crypts and lower part of the villous epithelium (arrows). Bars=200 µm.

Fig 3: Electron micrographs of GLP-1-positive cells in the chicken distal ileum stained with the PrLSB (a), PrCG (b) and PoCG (c) procedures. The cells contain round-to-oval secretory granules without a halo. The electron densities of the secretory granules observed with the three different experimental methods are medium and almost the same (arrows). The secretory granules of an enterochromaffin cell adjacent to the GLP-1-positive cell show polymorphous shapes and high-electron density (asterisk) (b). The post-embedding procedure shows fine preservation of the nucleoplasm and cytoplasm (c). Bars=1 µm. (d) High-magnification view of the secretory granules in panel (a). The DAB reaction products precipitate around the secretory granules (arrows) and in the cytoplasm (arrowheads). The profile of the granules is ambiguous. (e) High-magnification view of the secretory granules in panel (b). The particles of enhanced colloidal gold mainly precipitate around the secretory granules (arrows), and a few of them are located in the cytoplasm (arrowheads). The profile of the secretory granules is clearly observed. (f) High-magnification view of the secretory granules in panel (c). Almost all of the particles of colloidal gold are diffusely arranged on the secretory granules (arrows), and very few of them are located in the cytoplasm (arrowheads). The profile of the secretory granules is very clearly observed. Bars=200 nm.