Topography, irrigation, and histology of the thyroid gland of New Zealand rabbits (Oryctolagus cuniculus Linnaeus, 1758)

The objective of this study was to describe the topography, arterial irrigation, and microscopy of thyroid glands of thirty male specimens of New Zealand rabbits (Oryctolagus cuniculus). The aorta-thoracic system was analyzed by aorta thoracic cannulation and fixed in a 10% aqueous formaldehyde solution. Right and left lobes, and the isthmus of the thyroid gland were collected from only three rabbits for microscopic analyses. The procedure followed usual histological routine and histological sections were stained with Hematoxylin/Eosin. The thyroid gland consists of two flat, elongated lobes located ventrolateral to the trachea. Topographically, there is a close relationship between this gland and lateral surfaces of the first five tracheal rings, just below the cricoid cartilage and between the right and left common carotid arteries. The arterial supply to the thyroid gland in both antimers is performed by the thyroid artery, a branch of the common carotid artery. Following its origin at the level of the first tracheal ring, the thyroid artery continues in a caudocranial path. It reaches the cranial part of the thyroid gland and is divided into several branches that are distributed in this organ. The histological sections reveal that the cellular aspect of the isthmus region maintains the same organization and characteristics observed in the thyroid lobes. The thyroid gland in Oryctolagus cuniculus is small, consisting of two bilateral lobes united by an isthmus that presents glandular tissue.