Structural Changes Leading to Spore Formation in the Myxosporidian Parasite Ceratomyxa Shasta Nobel
Ceratomyxa shasta is a myxosporidian effecting mortalities of various species of salmonidae along the western regions of the North American continent.1,2 It is generally accepted from studies of myxosporidian infected t i ssues that the trophozoi tes undergo hi stozoi c development into multi- nucleated complexes which eventually form 2 characteristic spores in the mother cell. Most of the studies of Ceratomyxa have been with the light microscope3 and because of the small size of the parasite much of the structural details were not evident.For the electron microscopic analysis of the sporont and the developing spore of C. shasta two sources of experimentally infected specimens were examined. These were thin sections of free floating developmental forms from the gall bladder and thin sections of intestinal caecae fixed at 2, 7, 14 and 21 days following infection. The trophozoites measuring 20 μm in diameter were observed to increase in number by 14 days, infecting the connective tissue layer between the intestinal epithelial mucosa and the muscularis layer.