Features of morphology of the skin of the root of the tail of cattle of different age groups as a suspected factor in the incidence of chorioptosis

Relevance. In the literature, when describing the clinical signs of chorioptotic invasion of cattle, it is indicated that this is a widespread chronic invasive disease of adult livestock. However, it was not possible to find data in the literature on the causes of morbidity of adult livestock. The purpose of our study was to conduct comparative histological studies of the skin of the tail root area in cattle of different age groups.

Methods. The research was carried out on cattle in the livestock area of the Gatchina municipal district of the Leningrad region. For histological studies, the skin of the tail root area was taken from clinically healthy animals of a black-andwhite Holstein breed: bulls aged 1 year and adult dairy cows aged 5.5 years. By microscopic analysis of the manufactured preparations, the general histological structure of the skin of animals of different age groups, the morphology of its individual layers in a comparative aspect were studied.

Results. It was found that the mesh layer of the dermis is more developed in adult animals than in young ones. Collagen fibers in dairy cows have the greatest thickness compared to young animals, they fit tightly together, the ligature loops lie thickly, forming a diamond-shaped ligature. Histological examination showed an insignificant number of cells in the reticular layer of the dermis in adult animals. In young animals, collagen bundles of the mesh layer of the dermis have a less dense ligature, there are more rare, stretched and not completely finished diamond-shaped structures. In some cases, the bends of the collagen bundles are so rare that the diamond-shaped figures are invisible. But the number of cellular elements in young animals, unlike adults, is increased.

It can be assumed that the morbidity of adult animals is explained by the peculiarities of the structure of the dermis, in particular its richer collagen fibers of the mesh layer, since such a denser structure of the mesh layer of the dermis is a good "foundation and foundation" for the cellular the layer where the blood vessels are located to nourish the cells of the epidermis.

For more fundamental conclusions, we will continue deeper morphometric studies with the counting of cellular elements in the layers of the epidermis and the measurement of the layers of the dermis.

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