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Korean J Parasitol > Volume 32(3):1994 > Article

Original Article
Korean J Parasitol. 1994 Sep;32(3):171-176. English.
Published online Sep 20, 1994.  http://dx.doi.org/10.3347/kjp.1994.32.3.171
Copyright © 1994 by The Korean Society for Parasitology
Relation of cyst counts with numbers of total nuclei of Pneumocystis carinii in rats
S T Hong,*J S Yu and M Lee
Department of Parasitology and Institute of Endemic Diseases, Seoul National University College of Medicine, Seoul 110-799, Korea.
Received August 12, 1994; Accepted August 25, 1994.


Wistar rats were induced of Pneumocystis carinii infection by injection with methyl-prednisolone to correlate the cyst counts and numbers of nuclei. Seven sections of the lungs were examined by impression smears and also whole lung homogenates were screened for nucleus counting for each rat. At the first week of the experiment, all of the impression smears except one were cyst negative but trophic forms were counted around 106. At the third week, the cysts appeared one per 20 immersion oil lens fields. The nuclei were on the order of 107 at this period, and this amount of Pc is regarded as the limit of cyst detection on impression smears. When the nuclei were over 109 in the lungs, the cysts were counted about 50 in 20 microscopic fields. The organisms were distributed in the lungs without any predilection focus. The present data suggest that the trophic forms, proliferate first and the cysts appear later in the lungs.


Figs. 1-2
Fig. 1A. Impression smear of the right upper lobe of the lungs, W28-5 rat, 1 week after immune suppression. No cysts were observed, Diff-Quik stained, original magnification × 1500. B. Smear of the whole lung homogenate (10 fold dilution) of the rat W28-5. Two nuclei (arrows) of P. ccarinii were found in this field. Diff-Quik stained, original magnification × 1500. Fig. 2.A. Impression smear of the right upper lobe of the lungs, W29-6 rat, 6 week after immune suppression. Three cysts (arrows) and many trophic forms (arrow heads) were observed in this field, Diff-Quik stained, original magnification × 1500. B. Smear of the whole lung homogenate (100 fold dilution) of the rat W29-6. Numerous nuclei of Pc trophic forms (arrow heads) and a cyst (arrow) were found in this field. Diff-Quik stained, original magnification × 1500.

Fig. 3
Correlation of the cyst counts with numbers of nuclei of P. carinii from the rat lungs. Each dot represents one rat. The number of cysts is the count in 20 immersion oil lens fields, and the number of nuclei is the total count of nuclei in the lungs of a rat marked on the logarithmic scale.


Table 1
Numbers of cysts and nuclei of Pneumocystis carinii from rats

Table 2
Number of cysts of Pneumocystis carinii on impression smears by the lung locations

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