Features in the topography and morphology of the thyroid glands in chickens, turkeys, and ducks

Р. Yonkova, P. Stoyanova, D. Kanakov and E. Vachkova

Abstract: The goal of this study was to establish some topographical and morphological peculiarities of the thyroid glands in chickens, turkeys, and ducks. On this basis, we offer practically easy access to reveal and sampling the thyroids in each of the three species of birds. Thyroid glands of 12 broiler chickens, 12 North Caucasian turkeys, and 12 Mulard ducks were examined in situ after slaughter. Entire glands from 6 birds of each avian species were extirpated, fixed in formalin, and processed by standard procedures to obtain histological sections. The latter were stained with Alcian-Blue – PAS kit. In broiler chickens and turkeys, observation and sampling of the thyroid glands were performed through cranial or ventral access. The cranial one was carried out by strongly pulling the neck in the cranial direction. The thyroids were discovered at the level of thoracic inlet in close proximity to the last thymus lobes. The right thyroid gland in chickens and turkeys formed a common glandular cluster with the right parathyroid glands. The left thyroid was entirely separated from the corresponding parathyroid glands. Due to the significantly more caudal position of the thyroids in ducks, they were found only after the ventral opening of the thorax at the level of the tracheal bifurcation. Direct contact with the thymus and the parathyroid glands was not observed. The thyroid colloid reacted positively after Alcian-Blue – PAS staining, and contrasted strongly against the background of the adjacent anatomical structures. In broilers and turkeys one or more thymus penetrations in the thyroid parenchyma were found. They were located subcapsularly or scattered between the thyroid follicles. Similar thymic penetrations were not detected in ducks. The established features in the topography and morphology of the thyroid glands in chickens, turkeys, and ducks could be successfully used by veterinarians in slaughterhouses during the sampling for antithyroid agents.

Keywords: Thyroids, topography, morphology, chickens, turkeys, ducks

Date published: 2023-02-23