Endodyogony and cyst formation of Sarcocystis gongyli (Trinci 1911) from the skink Chalcides ocellatus.

The heteroxenous life cycle of S. gongyli comprising both the skink Chalcides ocellatus (intermediate host) and the snake Spalerosophis diadema, herewith the process of cyst formation was followed by means of light and electron microscopy after experimental infection. Following migration of the merozoites to muscle fibres, they changed into globular metrocytes, meanwhile a parasitophorous vacuole enclosing them. As development proceeded the wall of the parasitophorous vacuole is thickened in the form of striated protrusions as well as the metrocytes underwent endodyogony producing large numbers of banana-shaped merozoites in the centre of the cyst. Mature microscopic sarcocyst appeared at 120 days p.i, and these were characterized by presence of stalky leaf-like protrusions in their primary cyst wall. Asexual multiplication of metrocytes occurred through endodyogony in which always the mother metrocyte produced two opposite merozoites.