Cells, Organelles: Histochemistry

#101 Small Intestine Periodic acid-Schiff (PAS) reaction and hematoxylin

Carbohydrates, e.g., glycogen, proteoglycans, glycoproteins, glycosaminoglycans, are demonstrated by this histochemical reaction (see description PAS on p. 97 and in textbooks). Their presence is indicated by a red reaction product. Such structures are termed PAS positive. Note the intense reaction at the apical surface of the epithelial cells and within scattered goblet cells (containing mucin) at the luminal surface. Nuclei are stained blue because the section was counterstained with hematoxylin.