Comparative morphology of human and laboratory animal ’s liver and gall bladder
The liver is one of the main targets for toxic substances and most drugs, which is why it is necessary to carefully study it in preclinical studies to identify pathological processes occurring in the liver. In this review, generalized data on comparative anatomy and histology of the liver of the most common experimental animals (rats, mice, rabbits, hamsters, guinea pigs) and humans are presented. The liver of man and laboratory animals has a similar anatomical and histological structure, in particular, the peculiarities of the biliary excretory and vascular system, as well as the innervation of the organ in its basic structure are fairly uniform. At the same time, there are a number of macroscopic and microscopic differences, which can cause difficulties for researchers in the planning stage of experiments, as well as in the analysis and interpretation of the data. The most striking difference is noted in the anatomical structure of the organ and, first of all, in the number of lobes. In humans, two main parts and two additional parts are distinguished, while in animals different authors consider 4 to 6 lobes. Important is the absence of gall bladder in rats, which, undoubtedly, must be taken into account when planning an appropriate study. The histological structure also has a number of features that can be regarded as artifacts or manifestations of pathology during research. Animals tend to vacuolate hepatocytes due to a more massive accumulation of glycogen, which dissolves when the material is posted. There is a possibility of invaginates, and some lines of mice, such as BALB, have fat inclusions in the cells, which gives a picture of fatty degeneration. In the species of animals examined (especially in mice), the presence of polymorphic cells and their polyploidy is noted. Also in adult rodents, the development of foci of extramedullaryhemopoiesis is possible, which is not normal in humans. There are some differences in the quantitative cellular composition of the organ - the location of Kupffer cells, stellate reticuloendotheliocytes.