Microsporidian spore wall: ultrastructural findings on Encephalitozoon hellem exospore.
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.
Bigliardi
E
E
Department of Evolutionary Biology, University, Siena, Italy.
Selmi
M G
MG
Lupetti
P
P
Corona
S
S
Gatti
S
S
Scaglia
M
M
Sacchi
L
L
D000818:Animals; D002473:Cell Wall / Q000648:ultrastructure; D002478:Cells, Cultured; D016819:Encephalitozoon / Q000648:ultrastructure*; D006801:Humans; D013170:Spores / Q000648:ultrastructure