Microsporidian spore wall: ultrastructural findings on Encephalitozoon hellem exospore

J Eukaryot Microbiol. May-Jun 1996;43(3):181-6. doi: 10.1111/j.1550-7408.1996.tb01388.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Wall / ultrastructure
  • Cells, Cultured
  • Encephalitozoon / ultrastructure*
  • Humans
  • Spores / ultrastructure