卡氏肺孢子虫超微结构观察

目的 观察Wistar大鼠肺组织中卡氏肺孢子虫生长发育的超微结构。 方法 45只雌性Wistar大鼠随机分为2组，实验组（35只）每周2次经皮下注射地塞米松（1mg/次），对照组（10只）不作处理同步饲养。分别于首次注射地塞米松后第1～10周内，每周取两组鼠肺组织，电镜下观察卡氏肺孢子虫的感染情况及其生长发育的超微结构。 结果 电镜下观察，卡氏肺孢子虫虫体主要寄生于Wistar大鼠肺泡腔内，也见于肺泡膈、肺巨噬细胞和中性粒细胞，虫体表面有管状突起，内含细胞核、线粒体、空泡、粗面内质网和丰富的核糖体。许多卡氏肺孢子虫滋养体附着于肺Ⅰ型上皮细胞，偶见附着于肺Ⅱ型上皮细胞，有的伸出1或多个较宽大的伪足，部分细胞质内发现核相关细胞器和纺锤微管。囊前期有早、中、晚3种类型，在其内发现代表减数分裂的联会复合体。包囊壁上有一增厚处，内有一孔隙。 结论 卡氏肺孢子虫生活史由滋养体、囊前期和包囊等构成，包囊壁增厚处孔隙的存在提示为囊内小体逸出的一种模式。

Observation on the Ultrastructure of Pneumocystis carinii

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 septem, 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. CONCLUSION: 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.