An ultrastructural study of Zschokkella leptatherinae (Myxozoa: Myxosporea) from atherinid fish, Leptatherina presbyteroides

The structure and development of Zschokkella leptatherinae from the hepatic ducts of Leptatherina presbyteroides (Richardson) were studied by transmission electron microscopy. Plasmodia are located in the lumen of hepatic ducts and they are not in close contact with the epithelial cells. The surface of the plasmodium is delimited by a single unit membrane. Numerous microvillous projections extend from the surface of the plasmodium. Pinocytic vesicles are situated beneath the cell membrane. The sporogenesis proceeds with the pansporoblast formation. The sporogonic cell undergoes a series of divisions until ten undifferentiated cells are present within the enveloping cell. Ten cells differentiate and divide into two sporoblasts; each has five cells including two capsulogenic cells, two valvogenic cells and one sporoplasm. Two spores are produced from one pansporoblast at the end of sporogenesis.