| Abstract: | SYNOPSIS. Sporogony of oocysts of Isospora rivolta from the dog was studied by observation of individual oocysts in hanging drop preparations. Oocysts were passed with the feces in the unsporulated sporont stage. Division of the sporont gave rise to 2 spherical sporoblasts. Each sporoblast elongated and developed into a transient double pyramid stage. This stage changed into the sporocyst, which then differentiated into the sporulated oocyst. Sporulation time was determined for 4 temperatures. At 20 C, 100% of the sporulating oocysts (Sz 100) had formed sporozoites by 48 hr. At 25 C, Sz 100 was 24 hr, at 30 C it was 16 hr, and at 38 C 8 hr. The percentages of sporulation at 20, 25, 30, and 38 C were 94, 97, 96, and 93, respectively. Oocysts incubated at 50 C for 4 hr did not develop or survive, since they failed to sporulate when reincubated at 30 C. |
