Quantitative cytoarchitecture of the liver of the shrew Crocidura russula (fam. Soricidae). Ultrastructural and morphometric comparison with rat liver.

The livers of two groups of the shrew Crocidura russula, kept under standardized physiological conditions, were investigated with electron microscopy and morphometry. The adaptations to the extremely high basal metabolism of these small mammals are reflected in the architectural characteristics of the hapatocytes, which, in comparison with those of the rat, show a smaller cell volume of the mononuclear hepatocytes (3,800 micrometers3), and increased number of cells per cm3 of liver tissue (250 X 10(6)), and a relative larger liver volume (4.85 ml per 100 g body weight). The ground substance is reduced by the other cell compartments to 4%. The volume density of the glycogen differs from 5-15% and the variation of the SER is from 10-20%. The RER (constant at about 35%) and the mitochondria (around 30%) form the main part of the cytoplasm of the hepatocyte. The mean volume of individual mitochondria amounts to 2.5 micrometers3. The chrondriome in the cell shows important numerical-volumetrical transformations, i.e, an increase in the individual volume of mitochondria correlating with a decrease in the number of the mitochondria per volume unit and vice versa. The adaptations to the high basal metabolism and the special conditions of life (short phases of activity, long resting times) are considered in relation to the possible functional activity of the megamitochondria.