title: [Observation on the ultrastructure of Pneumocystis carinii].
abstract: OBJECTIVE
  To study the life cycle and morphology of Pneumocystis carinii by ultrastructural observation.
  
  
  METHODS
  Wistar rat model of P. carinii infection was established by subcutaneous injection with dexamethasone. Lung tissue of the infected rats was used for the transmission electron microscopical study.
  
  
  RESULTS
  The organisms were mainly present in the lung alveolar cavity, and also in the alveolar septum, pulmonary macrophages and neutrophils. More trophozoites of P. carinii attached to the type I alveolar epithelial cells, and rarely to the type II alveolar epithelial cells. Most of these trophozoites showed pseudopodial evaginations on their pellicles. The nucleus-associated organelle and spindle microtubules were observed in some trophozoites. The precyst phase was in three forms: early, intermediate and late form. Synaptonemal complexes indicating meiotic nuclear divisions and a clump of mitochondria were also observed in the precyst. The pellicle of the cyst has a thickened portion with a pore. There were nucleus with nucleolus, mitochondrion, vesicles, endoplasmic reticulum and numerous ribosomes in the organisms, and tubular expansions on its surface.
  
  
  CONCLUSIONS
  The life cycle of P. carinii consists of trophozoite, precyst and cyst stages. The presence of a single pore in the cyst wall reveals that pore formation may be a mode of excystation for intracystic bodies of P. carinii.
authors: Department of Parasitology, Qingdao University Medical College, Qingdao 266021, China.
authors: Yu-Xiang
authors: YX
authors: Gong
authors: Zhi-Shang
authors: ZS
authors: Chang
authors: Zhong-Guang
authors: ZG
authors: Zhang
authors: Xian-Zhong
authors: XZ
authors: Zeng
authors: Jin-Shan
authors: JS
authors: Tan
authors: Rong
authors: R
authors: Zhao
authors: Yuan-Song
authors: YS
authors: Wang
mesh_terms: D000818:Animals; D005260:Female; D046529:Microscopy, Electron, Transmission; D045363:Pneumocystis carinii / Q000302:isolation & purification / Q000648:ultrastructure*; D011020:Pneumonia, Pneumocystis / Q000469:parasitology*; D011650:Pulmonary Alveoli / Q000469:parasitology*; D051381:Rats; D017208:Rats, Wistar