Observations on the eosinophilic granules in the dorsal papillae of the dog tongue.
The granules from epithelium of filiform papillae of the dorsal surface of dog tongue were characterized as eosinophilic in contrast to the classically described basophilic keratohyalin granules which stain characteristically with hematoxylin. The eosinophilic granules also stained with Sakaguchi oxine reaction indicating the presence of arginine. At the ultrastructural level the round or oval granules varied in size and electron density. The granules were often associated with ribosomes and/or tonofilaments and were not limited by membranes. These granules disappeared in the superficial layers of epithelium which was parakeratotic in nature. Our studies indicate that the eosinophilic granules belong to the class of keratohyalin granules which are known to be heterogeneous in their morphology and biological composition.