A correlative light microscopic, scanning and transmission electron microscopic study of the dog tongue fiiform...

Recent studies in our laboratories have suggested that the epithelial cells of the dog tongue filiform papillae are organized into clearly delineated epithelial cell columns within the papillae. However, the contributions of these epithelial cell columns to the surface morphology of the dog papillae was unknown. Therefore, the objective of this investigation was to conduct a correlative scanning electron microscopic (SEM), transmission electron microscopic (TEM) and light microscopic (LM) examination of these epithelial cell columns in dog filiform papillae to study their contribution to tongue surface morphology. By scanning electron microscopy the numerous conical filiform papillae observed on the anterior two-thirds of the dog tongue were curved posteriorly. In addition to these primary papillary projections, the papillae exhibited secondary conical projections. A number of conical tertiary projections were also located anteriorly at the base of the papillae. Correlative histologic studies revealed anterior and posterior epithelial cell columns for the primary projections, lateral columns for the secondary projections and 5-7 smaller cell columns corresponding to tertiary projections seen by SEM. Thus, it appears that there is a complex organization of the proliferating and differentiating epithelial cells in dog filiform papillae. These epithelial cell columns exist as distinct units and correspond to the various surface projections.