Histological sections of the head of Tropidodipsas sartorii . Sagittal section of the head of Tropidodipsas sartorii (USNM 561067) showing supra (sl) and infralabial (il) glands, and emphasizing the large duct (d-il) distended along the medial surface of the infralabial gland; Paraffin, Hematoxylin-eosin staining (A). Alcian blue pH 2.5 reaction showing mucous cells (m) and the large duct (d-il) distended in medial surface of the infralabial gland; Paraffin (B). Detail of the acini of the infralabial gland and its positivity to alcian blue pH 2.5; Paraffin (C). Acini in the posteriormost portion of the gland constituted by seromucous cells (sm) strongly stained by hematoxylin-eosin and mucous cells (m) slightly stained (D). Abbreviations: Hg, Harderian gland; sl, supralabial gland. Scale bar = 1 mm (A); 200 μm (B); 50 μm (C and D). Panel at the upper right corner denote position of the section in A.