The skin is composed of two main layers: the uppermost thin layer called the epidermis made of closely packed epithelial cells, and the inner thick layer called the dermis that houses blood vessels, h...The skin is composed of two main layers: the uppermost thin layer called the epidermis made of closely packed epithelial cells, and the inner thick layer called the dermis that houses blood vessels, hair follicles, sweat glands, and nerve fibers. These glands are found all over the skin’s surface, but are especially abundant on the palms of the hand, the soles of the feet, and the forehead.