Answer:
tunica intima (inner layer)
Explanation:
Walls of veins is composed of three layers, which are:
- A. Outer layer (tunica adventitia) is of connective tissue with the collagen fibers.
- B. Middle layer (tunica media) is of smooth muscle which are arranged circularly and the elastic fibers.
- C.Inner layer (tunica intima) which consists of specialized simple squamous epithelium which are also known endothelium which lines all the blood vessels and endocardium of heart.
