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

The ultrastructure and cytochemistry of merogonial and gamogonial stag es and early unsporulated oocysts of Goussia sparis in the intestine o f Sparus aurata were studied. The typical pellicle was observed in som e stages. The different stages might appear in intraepithelial or supr aepithelial positions, but they were always intracellular. First steps of two apparently different endomerogonies were observed in intra- an d supraepithelial positions, respectively. An apparent ectomerogony al so occurred in supraepithelial stages. Developing macrogamonts showed surface invaginations and were densely packed with ribosomes, well-dev eloped rough endoplasmic reticulum, mitochondria, amylopectin granules , lipidic droplets, and wall-forming-like bodies. The latter could par ticipate in the formation of the oocyst wall. Abundant and large mitoc hondria, together with residual nuclei, appeared in advanced microgamo nts. Microgametes showed two flagella with microtubul arranged accordi ng to the typical pattern. An increase in polysaccharide content was o bserved with coccidian development, reaching a maximum in zygotes and unsporulated oocysts.