CBSE Class 9 Answered

Epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina. The epidermis is avascular (contains no blood vessels) and is nourished by diffusion from the dermis. The four principal types of cells which make up the epidermis are keratinocytes, melanocytes, Langerhans cells and Merkels cells. The outermost layer of epidermis consists of 25 to 30 layers of dead cells. The top layer of the epidermis, the stratum corneum, is made of dead, flat skin cells that shed about every 2 weeks. The main function of epidermis is protection of the underlying layers of body.

In plants, the epidermis is the outermost layer of cells covering the leaves, flowers, stem, roots and young parts of a plant.