Anatomical particularity of the thyroid gland of the dromedary (Camelus dromedarius)

Anatomical particularity of the thyroid gland of the dromedary (Camelus dromedarius) This study contributed to learn the anatomical particularities of the dromedary's thyroid gland specially the Camelus dromedarius. For that study, 606 thyroid glands collected from camels slaughtered in a slaughterhouse that exist in Tozeur (south of Tunisia). This large sample of camels contained 438 males and 168 females aged between I and 18 years ago The animals were divided into two age groups to study the thyroid glands topography then into three age groups to study its weight characteristics. Our results show that the colour and the shape of several camels' thyroid gland are variable. The right and the left lobes were joined by a constant isthmus in the caudal side of the gland. This isthmus is missing only when one of the thyroid lobes is absent (16 cases). The thyroid glands weights of camels vary according to sex. It's is higher among males than among females (26.32 +/- 0.28 and 24.92 +/- 0.37 respectively g). However the weight of the isthmus is similar in both sexes with averages of 2.19 +/- 0.04 g and 2.07 g +/- 0.06 g respectively in males and females. The weight of the thyroid gland varies also according to age; it's higher in animals of the 2(nd) age group (30.05 g +/- 0.38 g) than the animals of the 3(rd) group (27.53 g +/- 0.58 g) and the 1(st) age group (19.25 +/- 0.31 g g). In camels, there is a slight dissymmetry in a topographic appearance between right thyroid gland lobe and left thyroid gland lobe. This particularity is constant in this species. The position of the thyroid gland, compared with the trachea, is on the sixth or seventh First tracheal rings. The right accessory thyroid lobes are present in eleven animals; however the left accessory lobe is present in forty eight animals. Let's also note that the right and left accessory lobes are present in eight animals. Only two animals of the sample chosen in this study have an accessory lobe squeezed in the right and the left principal thyroid gland. The average weight of the right accessory thyroid lobe is 2.11 +/- 0.87 g and the weight of the left accessory thyroid lobe is 2.42 +/- 1.28 g. Contrary to the majority of the other domestic mammals, the thyroid gland of the dromedary is irrigated by three thyroid arteries that they come from common carotid artery.