The innermost layer of mammalian epidermis is

Answer Details

The mammalian epidermis (the outermost layer of the skin) is composed of several distinct layers, arranged from the outermost surface inward:

1. Cornified layer (stratum corneum) - the outermost layer, consisting of dead, flattened, keratinised cells that form a protective barrier.
2. Granular layer (stratum granulosum) - cells contain keratohyalin granules; this is where cells begin to die as they move outward.
3. Malpighian layer (stratum basale and stratum spinosum combined) - the innermost, actively dividing layer. This is where new epidermal cells are produced by mitosis. It also contains melanocytes, which produce the pigment melanin responsible for skin colour.

The Malpighian layer sits on the basement membrane, which separates the epidermis from the underlying dermis. Because it is the germinative (actively dividing) zone, it is sometimes called the stratum germinativum.

The capillaries layer is not a layer of the epidermis at all. Capillaries are blood vessels found in the dermis beneath the epidermis. The epidermis itself is avascular (has no blood supply) and receives nutrients by diffusion from dermal capillaries.

The correct answer is the Malpighian layer, as it is the deepest (innermost) layer of the epidermis.