the disk in the fundus of the eye marking the point at which the optic nerve enters; it is accompanied by blood vessels, is oval, light in color and the blind spot of the retina.
ARTERIOLES. In arterioles, the tunica intima consists of a continuous endothelium and a very thin subendothelial layer. In addition, a thin, fenestrated internal elastic lamina is present in larger arterioles but absent in terminal arterioles. Generally, the tunica media consists of 2 layers of smooth muscle cells.
Describe the tunica externa. Its the outer tissue layer that forms a connective tissue sheath around the vessel, is primarily composed of collagen fibers with scattered elastic fibers and the fibers blend into adjacent tissue anchoring the blood vessel to body tissue.î î î.ts the outer tissue layer that forms a connective tissue sheath around the vessel, is primarily composed of collagen fibers with scattered elastic fibers and the fibers blend into adjacent tissue anchoring the blood vessel to body tissue. î î î.