Abstract: Histological studies on the arterial wall of main arteries from the ascending aorta to the pectoral and abdomino-inguinal mammary glands of indigenous dogs in different reproductive stages were observed using a light microscope. Based on the histological characteristics and organization of connective tissue fibers and smooth muscle cells in the tunica media, the arterial segments were clearly identified into elastic, transitional and muscular types. Every artery belonging to the three types had different morphological structures at different levels. The artery distant from the heart gradually decreased its elastic lamellae in the tunica media as well as its elasticity and at the periphery of the arterial tree the elastic lamellae were replaced by the smooth muscle cells. The type of the arteries does not depend on the size or diameter of the arteries but depend on the relative distance from the heart. It is assumed that the histological arrangements of tissues in the arterial walls are certainly closely related to the functional demand of the mammary glands.