Epidermis

The four primary layers of the epidermis are visible image. Begin by distinguishing the epidermis from the dermis, visible here as the lighter colored dermal ridges. The stratum basale is the first layer of the epidermis and sits on top of the basement membrane superficial to the dermis. Superficial to the stratum basale is the stratum spinosum. The cells of the stratum granulosum become more flattened and stain noticeably darker than those of the lower layers. The stratum corneum has the most flattened appearance, displaying sheets of keratin.