title: Microsporidian spore wall: ultrastructural findings on Encephalitozoon hellem exospore.
abstract: A study of the spore wall of Encephalitozoon hellem was performed on thin sections, freeze-fracture, and deep-etched samples to obtain information on spore wall organization and composition. Our observations demonstrate that the spore wall is formed by an inner 30-35 nm electron-lucent endospore and an outer 25-30 nm electron-dense exospore. The exospore is a complex of three layers: an outer spiny layer, an electron-lucent intermediate lamina and an inner fibrous layer. Freeze-fracture and deep-etching techniques reveal that the intermediate lamina and the inner fibrous layer result from the different spatial disposition of the same 4-nm thick fibrils. In thin sections the endospore reveals a scattered electron-dense material that appears in the form of trabecular structures when analyzed in deep-etched samples. The presence of chitin in the exospore is discussed.
authors.affiliation: Department of Evolutionary Biology, University, Siena, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Bigliardi
authors.forename: M G
authors.initials: MG
authors.lastname: Selmi
authors.forename: P
authors.initials: P
authors.lastname: Lupetti
authors.forename: S
authors.initials: S
authors.lastname: Corona
authors.forename: S
authors.initials: S
authors.lastname: Gatti
authors.forename: M
authors.initials: M
authors.lastname: Scaglia
authors.forename: L
authors.initials: L
authors.lastname: Sacchi
mesh_terms: D000818:Animals; D002473:Cell Wall / Q000648:ultrastructure; D002478:Cells, Cultured; D016819:Encephalitozoon / Q000648:ultrastructure*; D006801:Humans; D013170:Spores / Q000648:ultrastructure