[Contributions to the life-cycle of Frenkelia. II. The asexual development of Frenkelia clethrionomyobuteonis in the bank vole (author's transl)].

A description of the asexual development of Frenkelia clethrionomyobuteonis in the European bank vole (Clethrionomys glareolus) is given as observed in experimental infections with sporocysts from buzzards' faeces. Between the 5th and the 8th day following the oral administration of sporocysts a first schizogony could be observed in liver parenchymal cells of the mammalian host. In impression smears the banana-shaped merozoites measured on an average 7.6 X 2.2 mum. Only after the 18th day were small round cysts filled with metrocytes detected in the brain and spinal cord. During the first month after infection the cysts increased their size only gradually measuring 15 to 40 mum. After 2 months they accelerated their growth and reached in the course of 3-4 months a diameter of 300 to 400 mum. Cyst formation could not be observed in organs other than the central nervous system. Cysts older than half a year frequently showed central degeneration, but in all cases viable cystozoites persisted in the peripheral zones. The infection could be transmitted from vole to vole by intraperitoneal injection of merozoites in a suspension of liver cells from the 7th day p.i. Congential infections did not occur in the offspring of mothers infected during or before pregnancy. The infectivity of the final products of the sexual development in the buzzard is limited to the bank vole.