[Morphofunctional changes in hepatocytes during the early postnatal development of rats experimentally infected with the intestinal protozoan pathogen, Cryptosporidium parvum (Coccidia, Sporozoa)].

Morphofunctional changes in hepatocytes of 10-14-day old rats were followed in norm and after experimental infection with different doses of oocysts of Cryptosporidium parvum. The liver index (ratio between the liver and body masses) varied with the intensity of invasion on the background of slowing down up to the total cessation of animal growth rates, and all this obviously pointed to severe pathology. In the infected rats, some cytological indices were shifted compared to the norm: protein amount and the average number of genomes per hepatocyte were seen to increase, the normal ratio between cells with different ploidy levels being violated. The particular correlation analysis was employed to distinguish between the ontogenetic (animal growth related) and pathologic (related to the infection intensity) polyploidization and hypertrophy in hepatocytes. In 10-14-day old rats, the former is affected primarily by the increase in the share of multinuclear hepatocytes, whereas the latter is accomplished by the increase in the number of cells with polyploid nuclei (4c and 4c x 2 cells). In the heavily infected rats, the ontogenetic polyploidy was almost totally suppressed due, presumably, to their growth rate inhibition, the rise in hepatocyte ploidy resulting form the obvious pathological changes in the liver. In the infected rats, the ontogenetic hypertrophy of hepatic parenchymatous cells was not manifested, and the observed protein accumulation in hepatocytes also resulted from the pathological changes in the liver. It is obvious that changes in cell hypertrophy (protein content) may serve as a more susceptible tool that readily perceives the host's stress experienced due to the parasitic infection (cryptosporidiosis), than cell ploidy: the levels of the respective responses of these two parameters differing by 4 times. However, due to the known reversible nature of hypertrophy, it cannot be used for the aims of a long-term prediction about the future mode of liver functioning in the animal that survived cryptosporidiosis. Unlike, such a parameter as frequencies of hepatocytes with different ploidy levels is much more useful in this respect.