Complex Carbohydrates in the Cyst Wall of Histriculus similis

The ultrastructure of the cyst wall has been studied in severa! hypotrichous ciliates. In Oxytrichafallax (Grimes, 1973),Pleurotricha sp. (Matsusaka, 1976), Stylonychia mytilus (Walker et al., 1975), Gastrostyla steinii (Walker et al., 1980) and Laurentiella acuminata (Gutierrez et al., l 980), the cyst wall is composed of four layers called, from outside to inside :the ectocyst, meso­ cyst, endocyst and granular layers. In these ciliates a resorption of cilia and kinetosomes occurs during encystment, and the mature cyst is termed kinetosome resorbing. Diophrys scutum (Walker & Maugel , 1980) has a three layered cyst wall and the mature cyst is non kinetosome resorbing. In the present work a structural and cytochemical study of the cyst wall in Histriculus similis was carried out by means of light microscopy and transmission electron microscopy .