Classification of Adrenal Ectopias and Their Frequency in Rats

Adrenal gland ectopias develop as a result of changes in the migration ways of intermediate mesoderm cells and are characterized by a variety of location options, often remaining asymptomatic in ontogeny. In humans, only a few clinical cases of adrenal ectopias were reported, while in rats, variants of their localization relative to the adrenal capsule were described. No data on the subtypes of adrenal ectopias or their frequency are found in literature. The purpose of the study was to determine possible localizations of ectopic adrenal tissue and its size, develop a classification of ectopias based on their external and internal structure, and calculate the frequency of each of the subtypes in mature rats. Materials and methods. Histological preparations of the left and right adrenal glands of 646 mature male rats were analysed by means of light microscopy. The type of ectopia was determined using a microscope lens at ×10 magnification, and its subtypes, using ×20 and ×40 lenses. The area of ectopias was measured in the computer program Nis-Elements BR 4.60.00. Results. In mature male rats, adrenal ectopia was detected in 27.90 % of cases (180 rats out of 646). All ectopias, depending on the position relative to the capsule, were divided into three types: intracapsular (53.88 % of cases), extracapsular (25.56 % of cases) and extraorganic (20.56 % of cases). The following subtypes of ectopias were distinguished: by shape (round/oval/irregular), by internal structure (diffuse/zonal; cellular/non-cellular) and by the number of ectopias in one and the same animal (single/group). Single, diffuse, non-cellular, and oval subtypes prevailed among the subtypes. Despite the fact that in some cases intracapsular and extracapsular ectopias were the largest in size, the highest median value and the smallest spread of data were identified in extraorganic ectopias.