Under the light microscope, the epithelium of filiform papillae consists of an anterior and a posterior side. On the anterior side of filiform papillae the epithelium exhibited characteristics of soft keratinization, while on the posterior side – there were characteristics of hard keratinization. Conical papillae were covered by nonkeratinized epithelium. The keratinized layer was observed only on their ends. The filiform and conical papillae were separated by the interpapillary epithelium, which does not keratinize. The epithelium of the filiform and conical papillae were composed of three layers, i.e. basal, intermediate, and superficial layer.

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