Light and electron microscopic study of the tongue in the White-eared bulbul (Pycnonotus leucotis)

The aim of the present study was to investigate the light and electron microscopic structure of the tongue in White-eared bulbul (Pycnonotus leucotis). Six adult White-eared bulbul (3 males and 3 females) in Shahrekord district were used in the investigation. Samples of the apex, body and root of the tongue were prepared routinely for light and electron microscopic study. Results showed that the tongue is characterized by an elongated triangular format. At a point, approximately 2/3 the length of the lingual corpus there is a distinct depression, separating the caudal one-third of the lingual corpus from its rostral two-third. On the dorsal surface of the apex and body of the tongue, a median groove is found. A unique feature of the tongue in White-eared bulbul is the presence of many fine overlapping needle-shaped processes at both lateral sides of the anterior lingual apex. A single row of large conical papillae is observed symmetrically in the marginal region between the body and root of the tongue. The mucosa of the tongue is covered with a thick stratified squamous epithelium, which is cornified only on the ventral surface of the apex. The periodic acid schiff (PAS) positive lingual salivary glands can be classified as dorsolateral and mediodorsal salivary glands. The compound tubular dorsolateral glands extend from the apex of the tongue to both sides of the laryngeal cleft. The compound tubulo-alveolar mediodorsal glands are found in the lingual root. At electron microscopic level, many fine openings of these glands are scattered throughout the dorsal surface of the lingual root. Neither the morphology nor the dimensions of the tongue show sex-specific differences.