Some ultrastructural data on

Sections of corneal tissue infected with Microsporidium ceylonensis were restained or processed for electron microscopy. Confirmation was obtained that the parasite develops in macrophages and that spores are uninucleate. New information is provided that sporoblasts and spores develop synchronously within a membrane in the host cell, spores have an anisofilar polar tube of 6-10 wide coils and 2-3 narrow coils and details are given of the spore wall and internal organisation. The parasite was compared on the one hand with Encephalitozoon, which exhibits asynchronous intravacuolar development of merogonic and sporogonic stages and has spores with isofilar polar tubes and on the other hand with species reported from mammals, of which the sporogonic stages develop synchronously within sporophorous vesicles and the spores have anisofilar polar tubes. Even so, a generic emplacement could not be established. Attention is drawn to the similarities between M. ceylonensis and Nosemo sp. described from the cornea of a woman in Botswana

Ultrastructural and molecular analysis of Bowman's layer corneal dystrophies: an epithelial origin?

PURPOSE: Two mutations (R555Q and R124L) in the BIGH3 gene have been described in anterior or Bowman's layer dystrophies (CDB). The clinical, molecular, and ultrastructural findings of five families with CDB was reviewed to determine whether there is a consistent genotype:phenotype correlation. METHODS: Keratoplasty tissue from each patient was examined by light and electron microscopy (LM and EM). DNA was obtained, and exons 4 and 12 of BIGH3 were analyzed by polymerase chain reaction and single-stranded conformation polymorphism/heteroduplex analysis. Abnormally migrating products were analyzed by direct sequencing. RESULTS: In two families with type I CDB (CDBI), the R124L mutation was defined. There were light and ultrastructural features of superficial granular dystrophy and atypical banding of the "rod-shaped bodies" ultrastructurally. Patients from three families with "honeycomb" dystrophy were found to carry the R555Q mutation and had characteristic features of Bowman's dystrophy type II (CDBII). CONCLUSIONS: There is a strong genotype:phenotype correlation among CBDI (R124L) and CDBII (R555Q). LM and EM findings suggest that epithelial abnormalities may underlie the pathology of both conditions. The findings clarify the confusion over classification of the Bowman's layer dystrophies