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[Cryptosporidium spp.]

Cryptosporidium spp. oocysts are rounded and measure 4.2 to 5.4 µm in diameter.  Sporozoites are sometimes visible inside the oocysts, indicating that sporulation has occurred.

A

A:  Cryptosporidium sp. oocysts stained with Ziehl-Neelson modified acid-fast.  Image contributed by Oregon State Public Health Laboratory.