Features of the thymic morphology in hens and ducks

Abstract

The features of the thymic morphology in hens and ducks were studied. Samples were obtained from 3 adult birds of each species. They were studied by light microscopy using classical methods of morphological research. The tissue samples were fixed in 10% neutral buffered formalin and embedded in paraffin block and finally the sections were cut at 5-10 μm thickness using sliding microtome and stained with hematoxylin and eosin, according to Van Gizon and Weigert and impregnated with silver nitrate according to Kelemen. It was established that the thymus of birds was represented by isolated cervical parts, which, in the form of strands, were located under the skin on the lateral surfaces of the neck, along the trachea, along the course of the neurovascular bundle, and consisted of individual lobes. In hens 5 to 8 lobes were included in each thymus and extended from the 3-cervical vertebra to the start of the thoraco-abdominal cavity. Thymus of ducks consisted of 3-4 lobes and was located in the posterior third of the neck. Its cranial end was at the level of 10-11 cervical vertebrae, and caudal end reached 12 cervical vertebra. Individual lobes of duck’s thymus had a greater absolute mass than the lobes of hen’s thymus. They were also more separated from each other. Lobes of hen’s and duck’s thymus had a variety of shapes. Among them, there were mainly oval, convex-oval, beanshaped, rounded, flat and, sometimes, sickle-shaped. Morphofunctional units of the thymus were lobules, which consisted of a cortex and a medulla. In birds the medulla occupied a larger area than the cortex. In the medulla, there were Hassall’s corpuscles, that were better developed in ducks.