Further light microscopic studies on morphology and development of Pneumocystis carinii.

In order to add more advance in light microscopic investigation of P. carinii, phase contrast microscopy partly followed by wet giemsa stain and semiultrathin section of the lungs embedded in JB-4 plastic were studied. In phase contrast microscopy, small and large sized trophozoites of P. carinii were clearly recognized. Although movement of trophozoite was not found, rhythmic movement of intracystic bodies with filopodia was often seen in mature cyst. Those living organisms were then directly stained with Giemsa by infiltrating under the coverglass. Thus the organism could be investigated both in unstained and stained conditions. It is noticed with interest that 8 intracystic bodies seem to fill up the cavity of cyst when cell division is completed, then they liberate and become independent into spherical bodies, followed by banana-shaped or amoeboid forms with motility. An emphasis was done that semiultrathin section made from JB-4 plastic embedded lungs was quite useful for investigation of P. carinii infection. Several sizes of mononuclear thin-walked trophozoites, mature and immature cysts, and empty cysts were more clearly distinguished than any other light microscopical method ever reported.