Abstract: Mice were injected intracranially with stable Cryptococcus neoformans L-forms. The results showed that filamentous or large bodies could be found in the brains of some mice. Pathogenetic examinations indicated that C. neoformans isolated from these mice were different in size and irregular in shape on the solid hypertonic media. The characteristic pathological feature seen in main internal organs was interstitial changes accompanied by gathering of chronic inflammatory cells. The results demonstrate that: (1) The interstitial changes are significant feature of C. neoformans L-forms infection; (2) The infection of C. neoformans is mainly via respiratory tract where the pathogens turn into L-forms with the induction of macrophages and lysozyme ;therefore the pathological change of most pulmonary cryptococcosis is in the form of interstitial pneumonia; (3) the gathering of chronic inflammatory cells during the L-forms infection may be the cause of cryptococcal granulomas.

Key words: Cryptococcus neoformans, L-form, Variation