[Last Modified: ]
[Cryptosporidium spp.]

Oocysts of Cryptosporidium parvum, in wet mount, seen with differential interference contrast (DIC) microscopy.  The oocysts are rounded, 4.2 µm to 5.4 µm in diameter.  Sporozoites are visible inside the oocysts, indicating that sporulation has occurred.  (In comparison, oocysts of Cyclospora cayetanensis, another important coccidian parasite of humans, are twice larger and upon excretion are not sporulated, i.e., do not contain sporocysts.)