Developmental Morphological and Histochemical Studies of the Tongue in Japanese Quails (Coturnix japonica)

Abstract

The lingual apparatus of the birds was used to determine the food type of the birds. The tongue of the Japanese quail showed great plasticity in morphology, histology and function. Although little literature spoke in details about the developmental anatomy of the Japanese quail tongue and its attachment during embryogenesis and the post-hatching period, our data were carried out on 85 healthy random specimens arranged on 45 Japanese quail embryos with ages from the 5th day of incubation to hatching day old and 40 quail chicks with the age of 7, 14, 30 and 60 days old. Those investigations found that the primordium of the tongue arose from the oropharyngeal floor primordium as a clear elongated projection supported by basihyale at the 5th and 6th days old of the embryonated egg. The tongue primordium was attached by a thin layer of epithelium (frenulum linguae primordium). With age advancing, the tongue took different shapes, starting from a ‘U’ shape to a triangular elongated shape. Consequently, its parts were fully developed into a lingual apex that was supported by the paraglossale apical process and paraglossale corpus and the lingual body supported by both the posterior part of paraglossale and basihyale. Besides that, (ala linguae) primordia became more prominent as two oval projections with caudal serrated borders at the 10-day-old embryo which were supported by posterior processes of os paraglossale. But at 13 days old, the transverse papillary crest primordium began to appear, which consisted of caudally directed finger-like papillae. Those papillae were developmentally variable in number, shape and length. The lingual muscle primordia could be noticed: ceratoglossus, hypoglossus anterior and genioglossus muscles at 5, 6 and 7 days old of incubation, respectively. However, the genioglossus muscle showed a degenerative process at the 11-day-old embryo. Lingual glands were compound tubular and tubulo-alveolar end pieces, which its primordia appeared at the 7 and 8-day-old embryo. Histochemically, the glands showed different reactions to AB and PAS, and combined stains, which the developmental stains reaction ended with a slightly alcinophilic reaction.