Histomorphometry of Brachiocephalic Artery of Iranian Pigeon (Columba livia domestica)

Histological features of brachiocephalic arteries in different age groups of pigeons of both the sexes were investigated. Eighteen pigeons of 20, 50 and 120 days of age were euthanized to obtain left and right brachiocephalic arteries. Serial transverse sections of the brachiocephalic arteries were stained with hematoxylin-eosin stains. The diameter of the wall and the thickness of the tunica intima, tunica media and tunica adventitia were microscopically measured. The tunica media was the thickest of the three tunics.  In males, on day 20 and 50 tunica media of right brachiocephalic artery was thicker than the left one (P 0.05). On day 120, diameter of the right artery was more than the left one (P=0.01). In females, tunica adventitia of the left artery on day 50 and 120 was thicker than the right one (P=0.003 and P=0.004, respectively). On day 50, tunica media of the right artery was thicker than the left (P=0.014).  The thickness of tunica media of the right artery wall was more than that of the left. In addition, the diameter and thickness of tunica media of the brachiocephalic arteries decreased from day 20 to 50. However, post day 50 it showed an increase. Thickness of tunica adventitia of the right brachiocephalic arteries in females decreased from day 20 to 50. Then it increased after day 50. Diameter of the brachiocephalic artery in females on day 120 was thicker than males (P=0.04). Thickness of tunica adventitia of the right arteries in males was thicker than females on day 50 (P=0.01) and day 120 (P=0).  There was no difference between males and females in other cases (P>0.05). In conclusion, brachiocephalic artery in pigeons contained elastic lamellae to resist comparatively high arterial pressure than that of the peripheral arteries.