Eosinophilic granulocytes in the epidermis of <i>Oreochromis mossambicus</i> gill filaments studied <i>in situ</i>

Abstract

Granular cells were observed in the epidermis of isolated gill filaments using Normaski microscopy at×400 magnification. Granulocytes were motile and chemotactic to histamine (introduced via a micropipette into the filament) and to the products of degranulation of neighbouring granulocytes within the epidermis. The abundance of visible granulocytes within the epidermis of gill filaments was increased in the period following net capture, confirming their migratory ability. Cells isolated from gill tissue are poorly glass adherent. They are also eosinophilic and more dense than macrophages and lymphocytes on a discontinuous percoll gradient. They are identified as eosinophils on the basis of these characteristics.