Innervation and osteoclast distribution in the inferior pharyngeal jaw of the cichlid Nile tilapia (Oreochromis niloticus).

In addition to an oral jaw, cichlids have a pharyngeal jaw, which is used for crushing and processing captured prey. The teeth and morphology of the pharyngeal jaw bones adapt to changes in prey in response to changes in the growing environment. This study aimed to explore the possible involvement of the peripheral nervous system in remodeling the cichlid pharyngeal jaw by examining the innervation of the inferior pharyngeal jaw in the Nile tilapia, Oreochromis niloticus. Vagal innervation was identified in the Nile tilapia inferior pharyngeal jaw. Double staining with tartrate-resistant acid phosphatase and immunostaining with the neuronal markers, protein gene product 9.5, and acetylated tubulin, revealed that osteoclasts, which play an important role in remodeling, were distributed in the vicinity of the nerves and were in apposition with the nerve terminals. This contact between peripheral nerves and osteoclasts suggests that the peripheral nervous system may play a role in remodeling the inferior pharyngeal jaw in cichlids.