Fine Structure of the Oocyst Walls of Isospora serini and Isospora canaria and Excystation of Isospora serini From the Canary, Serinus canarius L.

Authors

• Clarence A. Speer, University of Montana - Missoula
• Donald W. Duszynski, University of New Mexico - Main Campus

Document Type

Article

Date of this Version

1975

Comments

Published in Journal of Protozoology 22:4 (November 1975), pp. 476-481. Copyright © 1975 Society of Protozoologists.

Abstract

Oocysts of Isospora serini and Isospora canaria, from the canary Serinus canarius, were broken, added to a cell suspension, fixed in Karnovsky's fluid, and studied in the electron microscope. The oocyst wall of each species had an electron- lucent inner layer, a more osmiophilic middle layer and an outer layer of electron-lucent (I. serini) or electron-dense material interspersed with some electron-lucent material (I. canaria). A few, relatively large lipid-like bodies were present in the outer or middle layer of the oocyst wall of I. canaria. As many as 9 membranes were present in the oocyst wall of I. canaria and 3 in that of I. serini. When exposed to a trypsin-sodium taurocholate fluid, sporozoites of I. serini excysted from 5-month-old sporocysts in vitro, but not from sporocysts stored for more than 6 months. No excystation occurred in l5-month-old I. canaria sporocysts. Similarities and differences in excystation between I. serini and other Isospora, Eimeria, and Sarcocystis species are discussed.