The ultrastructure of the clamp wall of the monogenean gill parasiteGastrocotyle trachuri

Abstract

The clamp wall ofGastrocotyle trachuri has been found to consist predominantly of radially orientated myofibres. Nearly all the myofibres appear to be almost completely filled with myofilaments; these being of two kinds, thick and thin ones arranged in a manner similar to that observed in other platyhelminth muscles. Nothing resembling dense bodies was observed within the fibres, but at both ends of the fibres electron dense attachment plaques are present. These attachment plaques appear to have a dual function acting both as hemidesmosomes and as attachment points for the thin filaments. The detailed structure of the fibres suggests that the clamp wall is in fact composed of single radially orientated sarcomeres.