Postcystic development of Blastocystis hominis

A concentrated suspension of Blastocystis hominis cysts was inoculated into Jones' medium and removed after 24 h for study of their development at the ultrastructural level. The parasite divides in the cyst, and up to three d aughter cells can be seen. During this process the cyst wall dissolves, lea ving behind thin membranous remnants. Excystation occurs mostly by the emer gence of the daughter cells through an aperture in the outer fibrillar coat . Before excystation the vacuolar and the granular stages form and the daug hter cells develop their own fibrillar layer.