Abstract
Glycoproteins within mucus secreting cells of airway epithelium can be subdivided into two groups, acid and neutral. The acid glycoproteins include sialylated glycoproteins which are either sensitive or resistant to the enzyme sialidase, and sulfated glycoprotein. This study is concerned with the staining of glycoproteins by Alcian Blue at various pH levels combined with periodic acid-Schiff, as described by Jones and Reid.
Tracheal glands of the mouse, sublingual glands of the rat, and submaxillary glands of the dog were chosen for study because the nature of their glycoproteins is known. In the mouse there is a mixture of neutral and sialidase sensitive sialylated glycoproteins. In the rat only sialidase resistant sialylated glycoproteins are present. In the dog glycoprotein is sulfated. Serial tissue sections of each species were stained with a combination of the Alcian Blue and periodic acid-Schiff techniques. The result proved that the method is useful in identifying these glycoproteins. With Alcian Blue at pH+2.6 all acid glycoproteins stained blue. After sialidase treatment with similar staining, both sialidase resistant and sulfated glycoproteins stained blue. With Alcian Blue at pH=1.0 only sulfated glycoprotein stained blue. With Alcian Blue at pH=1.0 only sulfated glycoprotein stained blue. With this sequence of techniques, the neutral form of glycoprotein failed to stain with Alcian Blue and stained red.
