Classification of the parathyroid glands and the frequency of occurrence of their different types in mature rats

Abstract

The parathyroid glands play an important role in the regulation of calcium and phosphorus metabolism in the body. They are in close anatomical relationship with the thyroid gland and, considering their small size, can be accidentally removed during surgical interventions on it. To avoid mistakes, surgeons need to know the typical location of the parathyroid glands and non-typical variants. The laboratory animals, in particular white rats, can be used to improve the methods of surgical interventions and develop skills. Aim. To study the features of the location of the parathyroid glands relative to the lobes of the thyroid gland, classify into types and establish the frequency of their occurrence in mature rats. Material and methods. The study was carried out on 213 white outbred mature male rats. After taking the lobes of the thyroid gland with the parathyroid glands, the samples were processed according to the standard protocol. The sections of organs were stained with hematoxylin and eosin, toluidine blue, according to Van Gieson and to Grimelius. Light microscopy was used to study the location of the parathyroid glands on histological sections of the thyroid gland; the frequency of occurrence of each type was calculated. Results. In mature male rats, by location, one can distinguish typical, atypical and mixed parathyroid glands, occurring in 53.52, 45.54 and 0.94% of cases, respectively. Typical parathyroid glands in relation to the edge of the lobe of the thyroid gland are divided into centro-lateral and eccentrico-lateral; by invasion in the parenchyma of the lobes – marginal and incomplete; in shape – regular and irregular. Non-typical parathyroid glands are subdivided into single and group ones according to the number on the section of one lobe of the thyroid gland; by location – polar, intracapsular, occupying the center of the lobe or displaced from the center to the capsule; by invasion in the parenchyma of the lobes – without invasion, marginal, incomplete and complete; in shape – regular and irregular. Mixed parathyroid glands involve the presence of the typical and atypical glands by location in the same lobe of the thyroid gland. Conclusions. The parathyroid glands of mature male rats are characterized by a significant variability of localization in relation to the lobe of the thyroid gland – from superficial to complete invasion inside this organ, location in the pole or in the center, variability in shape and quantity.