Ultrastructure of the mitotic apparatus in Cryptococcus neoformans.

Mitosis in Cryptococcus neoformans was examined by electron microscopy. Observation of serial sections showed that the separation of chromosomes occurred in the karyokinetic nucleus in the bud, that the microtubule organizing center (MTOC) was composed of two globular elements and a bridged middle piece, and that the nuclear envelope of the karyokinetic nucleus was partially destroyed during mitosis. These findings are similar to those reported in the heterobasidiomycetous yeasts. In addition, some of the prophase cells showed extension of the karyokinetic nucleus into the bud unaccompanied by the MTOC and swelling of the middle piece of the MTOC.