Excystment of the metacercaria of the trematode Clinostomum marginatum

Abstract

The metacercaria  of Clinostomum marginatum,  a trematode parasite of heron and other fish eating birds excystedin chicken and toad bile and human urine.  Excystment occurs at 32°C in Chicken bile, 31°C in toad bile and at 33°C and 35°C in human urine.  Temperature less than 30°C do not cause excystment in all the media.  Excystment in C. marginatum  involves activation of the metacercaria by the media and its emergence through a hole created at one end of its spherical or ovoid wall.  The rest of the cyst wall remainsintact after the emergence of the metacercaria.