[Light and electron microscope studies on two types of giant schizonts (globidial schizonts) in the small intestine of sheep (author's transl)].

The jujunum of sheep was investigated for globidial schizont infection. Two types of giant schizonts, which had a maximum diameter of about 500 mum, were observed. Each type was found to contain morphologically different parasites. In type 1 the parasites were hook-shaped with a length of about 15-18 mum. Often they had an additional tight lacing at the apcial pole. The merozoites of the second type were spindle-shaped, measuring only 9-12 mum in length. Both types of parasites had 22 subpellicular microtubles beneath their pellicle. The parasites observed here differed clearly from those of globidial schizonts from the abomasum as well as from those of sarcosporidian cysts of the same host. In light microscopy the globidial schizonts from the jejunum of sheep seemed to be covered by a thin, mono-layered wall. By means of electron microscopy, it was shown, that this layer is identical with the host-cell cytoplasm enclosing utricle-like a giant, membrane-bound parasitophorus vacuole, which in both types of schizonts was closely filled with parasites and an enclosing ground substance. The host cell of the second type of schizonts had always numerous microvilli at the outer surface. The inner surface of the host cell formed numerous intravacuolar tubules of about 50 nm in diameter and with a considerable length. The cytoplasm of the host cells appeared always very condensed. Summarizing it was shown that the globidial schizonts from the jejunum differed clearly from those in the abomasum as well as from the sarcosporidian cysts. Thus it can be stated that more species than supposed up to now form giant schizonts within the digestive system of sheep causing the lesions of high economical importance.