Age-related ultrastructural features of the tongue of the rock pigeon Columba livia dakhlae in different three age stages (young, mature, and adult) captured from Egypt

This study represents the first attempt to describe the ultra-structural and histological features of different three age-stages (young, mature, and adult) of rock pigeon Columba livia dakhlae captured from Egypt. The elongated tongue with round lingual apex carried a lingual nail rostrally on lingual tip. The current work gave a first record of numerous descriptions as in young and mature, small lingual nail formed from aggregation of lingual scales, but in adult, the nail formed from lingual membrane without any lingual scales. The current work gave full descriptive methods of shape, directions, and distribution of filiform-like papillae with lingual scales among three age-stages on dorsal surface and lateral border of apex and body. The taste buds present only on the tongue of mature and adult pigeon. The only one transverse row in young took the wide V-shape but, wide U-shape in mature and adult. The papillae on the papillary crest took triangular spoonful-like shape in young and mature, but in adult take the shape of blunt tubercles. The current work was the first record of the presence of the openings of lingual glands on concave dorsal lingual surface of giant papillae and papillae of papillary crest in adult stage. The lingual membrane was thin one membrane in young and three to four layers in mature but, in adult it is well-developed and formed from 10-11 layers. The supportive entoglossum cartilaginous was extended rostrally till the apical part.