Ultrastructural studies in piscine epitheliocystis: evidence for a pleomorphic developmental cycle

Abstract

Abstract. The existence of a pleomorphic development cycle is demonstrated in epitheliocystis organisms obtained from fish of the following families: Sparidae, Sparus aurata L.; Mugilidae, Liza ramada (Risso), Liza aurata (Risso) and Mugil cephalus L.; Cichlidae, Tilapia mossambica (Peters) and Tilapia aurea × nilotica; and Serranidae, Dicentrarchus labrax L. Ultrastructure of the successive developmental stages, primary long cells, intermediate long cells and small cells are described as well as the division process between stages. An additional stage, the round cell, was found in infected chloride cells. The affinities between epitheliocystis organisms and known chlamydial organisms of vertebrates and invertebrates are discussed.