Nasal cavity of the farmed african catfish Clarias gariepinus fingerling from Eastern Nigeria: A microanatomical observation

Abstract

The nasal cavity microanatomy of farmed fingerlings of African catfish, Clarias gariepunus was investigated to fill existing knowledge gap on its histology from available literatures. This becomes very important as no gustatory cell was reported from previous researches on the fingerling digestive tract. A slice of nasal cavity of the farmed African catfish was fixed and processed through graded alcohol, cleared in xylene, embedded in paraffin wax, sectioned and stained with haematoxylin and eosin for routine light microscopy. On low magnification, the nasal cavity presented tube-like filamentous lamellae from the ventral basal raphe towards the dorsal roof. These filamentous lamellae that averaged eight per cavity occupied 4/5^th ventro-dorsal length of the cavity. Inter-filamentous cavity was observed. The heights of the lamellae progressively increased rostro-caudally. Ventrally at the base of each lamella were nerve fibre bundles. Higher magnification revealed that these filaments were lined by olfactory neuroepithelium containing tall ciliated simple columnar cells, supporting cells occasional mucous cells. The roof of the cavity was lined by  bi-stratified cuboidal caudally to low cuboidal cells rostrally. This histology suggests an organ actively involved in food search and selection through olfaction.

Key Words: olfaction, ciliated epithelium, histology, chemoreception, food selection