title: Ultrastructure of Chilomonas paramecium and the phylogeny of the cryptoprotists.
abstract: The ultrastructure of the cryptoprotist Chilomonas paramecium is reviewed and compared to earlier accounts. Distinctive features include a complex cytoskeleton which defines the cell organization and interconnects cell components; trichocysts which resemble those in other cryptoprotists; and two non-photosynthetic plastids. During mitosis there is partial dispersal of the nuclear envelope early in prophase but some remains at the nuclear periphery throughout mitosis. At metaphase chromosomes are arranged on the longitudinal axis of an elongated elliptical nucleus. During telophase the chromosomes decondense and the nuclear envelope reforms. Cell structure is compared with that in other cryptoprotists, and origin of this taxon of algae is discussed.
authors.affiliation: Division of Biology and Medicine, Brown University, Providence, RI 02912.
authors.forename: P
authors.initials: P
authors.lastname: Heywood
mesh_terms: D000818:Animals; D002923:Cilia / Q000648:ultrastructure; D056890:Eukaryota / Q000145:classification* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010802:Phylogeny