From: … And Now Microsporidiosis Ann Intern Med. 1995;123(12):954-956. doi:10.7326/0003-4819-123-12-199512150-00012 Figure Legend: Structure of a microsporidian spore.NosemaDepending on the species, the size of the spore can vary from 1 to 10 µm and the number of polar tubule coils can vary from a few to 30 or more. A equals the anchoring disk (the extrusion apparatus consists of the polar tube [Pt], tubular polaroplast [Tp], lamellar polarplast [Lp], and the anchoring disk and is used to identify microsporidia); D equals the nucleus, which may be single (such as in Encephalitozoonae and Enterocytozoonae) or a pair of abutted nuclei called a diplokaryon (such as in ); En equals the endospore, an inner thicker electron-lucent region; Ex equals the exospore, an outer electron-dense region; P equals the plasma membrane separating the spore coat from the sporoplasm (Sp); Pv equals posterior vacuole, a membrane-bound structure; R equals ribosomes, present in a coiled helical array. Reproduced with permission from Cali A, Owen RL. Microsporidiosis. In: Ballows A, Hausler W Jr, Lennette EH, eds. The Laboratory Diagnosis of Infectious Diseases: Principles and Practice. New York: Springer-Verlag; 1988:928-49. Date of download: 10/27/2017 Copyright © American College of Physicians. All rights reserved.