Other ultrastructural observations associated with Desmozoon lepeophtherii n. gen., n. sp. a and b) Secretions from mature spores (s) are sometimes observed that form multiple and regular layers which have a fine electron dense core, and surround the spore (white arrows). The secretions originate from the exospore surface and, when first produced, do not have an electron dense core (black arrows). c) At the border of a xenoma (white arrows) concentric whorls of the secretions have formed adjacent to a sporoblast (sb), the individual layers appear more compact but still maintain an electron dense core (black arrows). d and inset) Host cell nuclei of microsporidian-infected cells were frequently observed with intranuclear inclusions, which were of a crystalline appearance with a regular pattern. Scale bars a, b and d (inset) 500 nm, c 1 μm, d 2 μm.