Structural feature of Internal elastic lamina Endothelium Arteries andⅤeins Intima Media Tunica intimae 1. Endothelium 2. Subendothelial layer 3. Internal elastic membrane Adventitia nica eala medium-sized a Mainly smooth muscle Tunica adventitia external elastic membrane Mainly connective tissueStructural feature of Arteries and Veins: Tunica intimae 1. Endothelium 2. Subendothelial layer 3. Internal elastic membrane Tunica media Mainly smooth muscle Tunica adventitia external elastic membrane Mainly connective tissue medium-sized A