LIGHT AND ELECTRON-MICROSCOPE STUDIES ON CYSTS OF SARCOCYSTIS FUSIFORMIS IN MUSCLES OF CALVES INFECTED EXPERIMENTALLY WITH OOCYSTS AND SPOROCYSTS OF LARGE FORM OF ISOSPORA BIGEMINA FROM CATS

  • 1 January 1975
    • journal article
    • research article
    • Vol. 233  (2) , 261-276
Abstract
Young calves were infected with oocysts and sporocysts of the large form of I. bigemina from cats which were fed by raw beef containing S. fusiformis cysts. On the 98th and 160th day p.i. [post infection] the calves were killed and the development of S. fusiformis cysts in muscle cells was studied by light and electron microscopy. Two types of parasites were seen in the cysts, always situated within chamber-like hollows of the ground substance of the cyst: metrocytes and merozoites. There was no significant difference, except for size, in fine structure between the metrocytes of I. hominis-induced cysts and those from cysts after infections with the large forms of I. bigemina from dogs and cats. The fine structure of the cyst wall and cyst stages differed significantly from that of the cysts after infections with I. hominis and the large form of I. bigemina from dogs. The large forms of I. bigemina from dogs and cats probably are 2 different species. S. fusiformis if probably part of at least 3 coccidian life cycles. The terms I. bigemina and S. fusiformis must be changed.

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