Dorsal surface of the tongue; lingual papillae are covering the tongue surface; the interpapillar epithelium is sunken between the papillae and the interpapillar area is very narrow.

lp, lingual papilla.

SEM. Scale bar = 100 µm.

Fig. 2. Trachemys scripta elegans.

Taste buds can be recognized on the apical side of the lingual papillae due to their longer microvilli.

ec, epithelial cells; tb, taste bud.

SEM. Scale bar = 10 µm.

Fig. 3. Trachemys scripta elegans.

Dome-shaped bulges correspond to single cells.

cb, cell borders; mv, microvilli.

SEM. Scale bar = 1 µm.

Fig. 4. Trachemys scripta elegans.

Semithin section, stained with metyleneblue-azure II. Apical region of a lingual papilla, where taste buds can be found. The arrow indicates a taste bud. aep, apical epithelium;

ct, connective tissue; oc, oral cavity.

LM. Scale bar = 50 µm.

Fig. 5. Trachemys scripta elegans

Semithin section, stained with methyleneblue-azure II. Detail of Figure 4. The basal layer and the surface layer are distinct from the more intensively stained cells of the intermediate layers.

bl, basal layer, il, intermediate layers; sl, surface layer.

LM. Scale bar = 20 µm.

Fig. 6. Trachemys scripta elegans.

Semithin section, stained with methyleneblue-azure II. A connective tissue core arises from the lamina propria and penetrates deep into the center of each papilla, mucus cells dominate the view of the lateral epithelium. The arrow indicates a taste bud.

aep, apical epithelium; ct, connective tissue; lep, lateral epithelium.

LM. Scale bar = 50 µm.

Fig. 7. Trachemys scripta elegans.

Semithin section, stained with methyleneblue-azure II. Detail of Figure 6. In lateral regions of the papillae, only cells of the deep intermediate layer stain intensively; cells of the upper layers are moderately stained.

bl, basal layer; dil, deep intermediate layer; fc, fine granule cells; mc, mucus cells.

LM. Scale bar = 20 µm.

Standard fixation. Overall view of the lateral epithelium; cells of the upper cell layers can be differentiated into the columnar mucus cells and the fine granule cells. The arrow indicates the basement membrane.

bl, basal layer; ct, connective tissue; dil, deep intermediate layer; sil, superficial intermediate layer; sl, surface layer.

TEM. Scale bar = 10 µm.

Postfixation with osmium tetroxide/K-ferricyanide. A mucus cell of the lateral epithelium releases its content into the oral cavity, when the apical cell membrane opens (arrowhead).

g, secretory granules; m, mucus granules; oc, oral cavity.

TEM. Scale bar = 2.5 µm.

Standard fixation. Overall view of the apical epithelium. The arrow indicates the basement memebrane.

bl, basal layer; dil, deep intermediate layer; oc, oral cavity; sil, superficial intermediate layer; sl, surface layer.

TEM. Scale bar = 10 µm.