ULTRASTRUCTURE AND CYTOCHEMISTRY STUDY OF EIMERIA-SPARIS (PROTOZOA, APICOMPLEXA) STAGES FROM THE INTESTINE OF GILTHEAD SEA BREAM SPARUS-AURATA L (PISCES, TELEOSTEI)

The ultrastructure and cytochemistry of merogonial, gamogonial, and ea rly sporogonial stages of Eimeria sparis in the intestine of Spartus a urata were studied. Mature stages showed the typical pellicle, which w as lost in some transitional stages. An apparent unit membrane was see n in some immature stages. A parasitophorous vacuole, sometimes with m embrane vesicular invaginations, was usually observed. We propose that the stages located over the epithelium and the so-called epicellular stages be termed supraepithelial stages. Endomerogony was observed in intraepithelial and supraepithelial positions. Intraepithelial stages apparently starting ectomerogony were also detected. Electron-dense gr anules similar to wall-forming-like bodies of types 1 and 2 were obser ved. Microgametes exhibited two flagella. Cytochemistry study revealed scarce polysaccharides, if any, in merogonial stages and in microgamo nts. The occurrence of polysaccharides and amylopectin granules increa sed progressively in macrogamonts, macrogametes, zygotes, and early oo cysts. Lipidic droplets were scarce or absent in merogonial stages and abundant in maturing macrogamonts. Some glycoproteins were demonstrat ed in certain merogonial stages.