stylistic:style_transfer
Formation and composition of the cyst wall

Indicators of cyst formation in ciliated protists include varying degrees of ciliature resorption, with some ciliates losing both cilia and the membranous structures supporting them while others maintain kinetosomes and/or microtubular structures. De novo synthesis of cyst wall precursors in the endoplasmic reticulum also frequently indicate a ciliate is undergoing encystment.

The composition of the cyst wall is variable in different organisms. The cyst walls of bacteria are formed by the thickening of the normal cell wall with added peptidoglycan layers whereas the walls of protozoan cysts are made of chitin, a type of glycopolymer. The cyst wall of some ciliated protists is composed of four layers, ectocyst, mesocyst, endocyst, and the granular layer. The ectocyst is the outer layer and contains a plug-like structure through which the vegetative cell reemerges during excystation. Interior to the ectocyst, the thick mesocyst is compact yet stratified in density. Chitinase treatments indicate the presence of chitin in the mesocyst of some ciliate species, but this compositional characteristic appears to be highly heterogeneous. The thin endocyst, interior to the mesocyst, is less dense than the ectocyst and is believed to be composed of proteins. The innermost granular layer lies directly outside the pellicle and is composed of de novo synthesized precursors of granular material.