Tongue anato-histology of the oceanodromous adult Rastrelliger brachysoma (Bleeker, 1851) with a note on the comparison with the tongue structure of adult R. kanagurta (Cuvier, 1816)

Abstract

Anatomical and histological structures of the tongue tissue of Rastrelliger brachysoma and R. kanagurta were investigated. Anatomical structure of the tongue in R. brachysoma was poorly developed and was of triangular shape. The histological and histochemical technique showed the tissue to be principally composed of three layers: tunica mucosa, tunica submucosa and osteocartilagionous skeleton. Stratified epithelium of its mucosal surface was interrupted with several cell types including goblet cells and taste buds. Numerous teeth with elongated shape were also found centrally on the anterior tip of the tongue. They are found among a few dermal papillae of the tongue. Tunica submucosa consisted of connective tissue, blood vessels and pigment cells. When compared anatomically and histologically with that of R. kanagurta, the overall morphological was quite similar. However, some histological structures including taste buds and teeth of R. kanagurta were rarely seen. Rastrelliger kanagurta also tended to have more goblet cell than R. brachysoma. Rastrelliger kanagurta tended to possess less overall histological structures of the tongue. This difference could potentially cause by different feeding adaptation between the two species. Regardless of the differences found between the two species, both are still considered as herbivores.

Keywords

• Rastrelliger brachysoma
• R. kanagurta
• histology
• Thailand
• tongue tissue