Digestive gland ultrastructure of the tunicate,Halocynthia roretzi(Ascidiacea:Pyuridae)in relation to function

Objective:To examine the glycogen storage and lipid digestion,as well as detoxification of the digestive gland of the tunicate,Halocynthia roretzi.Methods:Tunicates used in this study were collected from tunicate aquafarm located in Hansan Bay on the southern coast of Korea.Light and electron microscopy was performed.Results:The digestive gland was divided into the tubular and blind ampulla portions.Fine vacuolar granules were present,and lipofuscin granules were confirmed in the cytoplasm of the epithelia of the blind ampulla portion.Epithelial cells of the blind ampulla portion could be classified into three types.Conclusions:The results indicate that these three types of cells are involved in glycogen storage,lipid digestion and detoxification.