title: Ultrastructure of Encephalitozoon sp. infecting the conjunctival, corneal and nasal epithelia of a patient with AIDS.
abstract: The ultrastructure of a species of Encephalitozoon infecting the ocular and nasal epithelia of a patient with AIDS is described. Development occurred in parasitophorous vacuoles, all stages had isolated nuclei and sporogony was disporoblastic. Spores had 5-8 coils of the polar tube, about 40 closely packed membranes forming the polaroplast, a single nucleus, abundant ribosomes and a posterior vacuole. Most of the mature spores in the conjunctival epithelium and many of those in the nasal epithelium had germinated within their parasitophorous vacuoles. The wall of the polar tube was made up of 2 membranes and eversion took place by an inner tube sliding through an outer tube. Polaroplast membranes became depleted in the spore at the onset of germination and may have contributed to polar tube formation. The sporoplasm, identified by its ribosomes, passed through the polar tube but was not enveloped by a membrane while doing so. Putative sporoplasms injected into host cell cytoplasm had acquired a surface membrane, possibly from the polaroplast, and an additional membrane, which became the boundary of the parasitophorous vacuole. As the emerging tube passed through cell boundaries it carried the plasma membranes forward with it and one of these could have been the origin of the parasitophorous vacuolar membrane. Early vacuoles, containing meronts and pre-spore stages, had a reticular matrix but vacuoles containing spores had a disrupted membrane and exhibited incursion of host cell organelles.
authors.affiliation: Department of Biology, Imperial College, London, UK.
authors.forename: E U
authors.initials: EU
authors.lastname: Canning
authors.forename: A
authors.initials: A
authors.lastname: Curry
authors.forename: C J
authors.initials: CJ
authors.lastname: Lacey
authors.forename: J D
authors.initials: JD
authors.lastname: Fenwick