Anatomical and histological study on thyroid gland in one humped camel (Camelus dromedarious)

BACKGROUND: Thyroid is an endocrine gland that influences many organs of the body and plays an important role in the metabolism of animals. However, little researches have been done about anatomical and histological characteristics of camel thyroid glands in Iran. OBJECTIVES: The aim of this study was to determine the anatomical and histological structure of thyroid gland in one-humped camel. METHODS: In this research, the anatomical characteristics and histological structure of the thyroid glands of 40, 6-10 year old one-humped, camels (20 males and 20 females) were studied by sectioning and staining with Haematoxylin & Eosin, Verhoeff and Toluidine blue by light microscope. RESULTS: The thyroid gland of one-humped camel was situated in lateral surface of the trachea. The right lobe was located slightly cranial to the left one lying on the caudal aspect of the larynx while both lobes were connected together by isthmus on the ventral surface of trachea. Maximum length, width and thickness of thyroid gland were 5.15±0.65, 2.25±0.75 and 0.9±0.5 cm, respectively in male camels and 5.55±0.5, 2.65±0.3 and 0.9±0.52 cm, respectively in female camels. Weights of the thyroid gland in male and female camels were 51.69±0.52 and 53.07±0.25 g, respectively. Histologically, the thyroid gland contained follicles, follicular epithelium and parafollicular cells in microscopic examination. The parafollicular cells were about 5% of the cell population. Large follicles were located in peripheral margin whereas small ones in central part of the gland. Central parts of the gland had richer vascular base in comparison with the peripheral parts. CONCLUSIONS: Anatomically and histologically, the thyroid gland of one-humped camel has no remarkable difference with other domestic mammals.