MECHANISMS OF MICROSPORIDIAL CELL-DIVISION - ULTRASTRUCTURAL-STUDY ONENCEPHALITOZOON HELLEM

The mitotic process in microsporidian Encephalitozoon hellem, a known human pathogen, has been studied with the aim of elucidating some ultr astructural aspects of its nuclear division. The presence of a nuclear spindle, of ''electrondense spindle plaques'' associated with the nuc lear envelope and of cytoplasmic double walled vesicles are reported. We suggest that these ''electrondense spindle plaques'' serve as foci for intranuclear and cytoplasmic microtubule arrangements, similar to the microtubule organizing centers within the centrosomes of animal ce lls. The extent to which the microsporidial division process is compar able with that of more familiar eukaryotes such as yeast cells is disc ussed.