Micromorphometric characteristics of the adrenal gland in birds

The adrenal gland is a peripheral organ of the endocrine system that directly affects the formation of bird productivity indicators, which is an important characteristic for the development of industrial poultry farming. The purpose of this study was a morphometric assessment of the microstructural components of the adrenal gland of birds of the order Galliformes (domestic quail, chicken, turkey), Anseriformes (Muscovy duck, domestic duck, and goose) and Columbiformes (common pigeon). Anatomical, histological, morphometric, and statistical research methods were used in this study. It was found that the thickness of the adrenal capsule of birds directly depends on their body weight and varies from 10.82 ± 0.56 µm (domestic quail) to 28.53 ± 1.36 µm (domestic turkey). Interrenal tissue compared to suprarenal tissue in Muscovy ducks, common pigeons, domestic ducks, and geese occupies a larger (Р < 0.001) area of the central zone (3.50, 2.77, 3.10, and 3.11 times, respectively) and peripheral zone (1.27, 2.71, 1.38, and 1.55 times, respectively) of the adrenal gland, which indicates its morphofunctional activity. The area of the venous sinuses in the central zone compared to the peripheral zone of the adrenal gland is larger in domestic quail by 2.80 times (Р<0.05), domestic chicken – by 3.62 times (Р < 0.05), domestic turkey – by 3.68 times (Р < 0.05), domestic ducks – by 5 times (Р < 0.01), domestic ducks – by 3 times (Р < 0.05), domestic geese – by 2 times (Р < 0.05). The common pigeon is characterized by a uniform placement of venous sinuses along the entire periphery of the adrenal gland and, as a result, similar indicators of their area in the peripheral and central zones. The index of the nuclear-cytoplasmic ratio of endocrinocytes of the adrenal gland of birds varies. It is the lowest in the cells of the second type of interrenal tissue (from 0.052 ± 0.004 in the common pigeon to 0.092 ± 0.016 in the domestic quail), slightly higher in the cells of the first type of interrenal tissue (from 0.065 ± 0.004 in the common pigeon to 0.111 ± 0.012 in the domestic turkey) and the largest in chromaffin cells of the supranarial tissue (from 0.102 ± 0.015 in the domestic chicken to 0.166 ± 0.018 in the common pigeon). It is recommended to use the established features of the morphometric indicators of the microstructural components of the adrenal gland of birds to create a base for its normal morphological characteristics. This allows assessing the morphological and functional state of the adrenal gland under several factors and pathology