Histological and electron microscopic studies of gills of Nile tilapia oreochromis niloticus from two wetlands differing in water quality

ABSTRACT

Histological and electron microscopic studies of gill tissue were carried out in specimens from two wild populations of Nile Tilapia Oreochromis niloticus, the first from River Nile and the other from a pond located in south Egypt [Assiut Governorate]. These two wetland ecosystems differ in. water quality. Scanning electron microscopy revealed that the arrangement of microridges on the pavement cell surfaces of gill epithelia was variable among two populations. From River Nile, pavement cells of gill filament and secondary lamnellae were similar for their surface architecture. Also, these cells of both filament and secondary lamella exhibit numerous long microridges with a fingerprint-like pattern. From the pond, Pavement cells of filament may vary from cells on which microridges form a complex pattern of concentric whorls to cells with a smooth central part without microridges, while pavement cells from the secondary lamellae are smooth surfaced with clearly defined cell boundaries by a long microridge. On the other hand, the transmission electron microscopy revealed that the pavement cells of secondary lamellae from the pond are thinner than those from River Nile. Differences in morphology of the pavement cells from two populations may be related to structural rather than functional differences