[The glands of the dorso-distal mucosa of the toad Bufo marinus (Amphibia: Anura) tongue: histology and ultrastructure ].

Frequently, the studies on the lingual epithelium ultrastructure in anurans do not show differences between filiform papilae and glandular epithelia in the non-sensory dorsal epithelium. To accomplish the study of glandular epithelium, samples of dorso-distalis mucosae of Bufo marinus tongue were processed for transmission electron microscopy and also semithin sections of the same material were used for light microscopy study. The results showed that the glandular epithelium is constituted by three different types of cells: (1) serous granular secretory cells; (2) mitochondria rich cells (CRM); and (3) ciliated cells. Detailed structures of each type of cell under light and electron microscopy were given. Notably, in the lingual portion studied, secretory cells showed no signs of exocytosis of their granules, thus suggesting that they do not have a basal or continuous rate of secretory activity. Additionally, the distribution, localization and structure of CRM in the gland epithelium suggest their participation in secretory cell maturation and/or function.