Ultrastructural demonstration of a pore in the cyst wall of Pneumocystis carinii.
The proposed life cycle of the opportunistic organism Pneumocystis carinii (PC) includes the formation of a thick-walled cyst containing haploid progeny. The progeny cells mature within the cyst and are somehow released, leaving a collapsed empty cyst behind. Pneumocystis carinii cysts containing 8 intracystic bodies (ICB) as well as empty collapsed cysts have been commonly observed. In this study a single pore in the cyst walls of PC was observed by transmission electron microscopy in infected rat-lung preparations. Presence of a single pore in the cyst wall of an empty but noncollapsed cyst and in collapsed, empty cysts suggests that pore formation may be a mode of excystation for ICB of P. carinii.
Itatani
C A
CA
Department of Biological Sciences, California State University, Long Beach 90840.
D000818:Animals; D008168:Lung / Q000469:parasitology; D008297:Male; D008854:Microscopy, Electron; D011010:Pneumocystis / Q000648:ultrastructure*; D011020:Pneumonia, Pneumocystis / Q000469:parasitology*; D051381:Rats; D017207:Rats, Sprague-Dawley