TABLE 5.

Morphological characteristics of microsporidia infecting humans

Characteristic	E. bieneusi	Encephalitozoon spp.	Nosema spp.	V. corneae	Pleistophora spp.	Trachipleistophora spp.
Size of spores (μm)	1.1–1.6 by 0.7–1.0	2.0–2.5 by 1.0–1.5	2.5–5.0 by 2.0–2.5	3.05–4.55 by 0.77–1.27	3.2–3.4 by 2.8	4.0 by 2.4
No. of coils of polar tubule	5–7	5–7	7–12	5–7	9–12	11
Arrangement of polar tube	Two rows	One row	One row	One row	Two rows	One or two rows
Nucleus	Unikaryotic	Unikaryotic	Diplokaryotic	Diplokaryotic	Unikaryotic	Unikaryotic
Vacuole	No vacuole, in direct contact with the host cell cytoplasma	Septated parasitophorous vacuole in E. intestinalis	No vacuole, in direct contact with the host cell cytoplasma	No vacuole, in direct contact with the host cell cytoplasma	Sporophorous vesicle	Sporophorous vesicle
Special features	Electron-lucent inclusion, development of the polar tubule beginning in the sporonts		Diplosporoblastic sporogony	Tetrasporoblastic sporogony, band-like sporonts, all stages are surrounded by a cisterna of host endoplasmatic reticulum	Multinucleate sporogonial plasmodia	No multinucleate sporogonial plasmodia, two different types of sporophorous vesicles and spores are formed during development of T. antropophtera