The stratum lucidum is a thin, clear layer of dead skin cells in the epidermis named for its translucent appearance under a microscope

Microscope

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

. It is found only in areas of thick skin, most noticeably on the palms of the hands and the soles of the feet.

Located between the stratum granulosum

Stratum granulosum

The stratum granulosum is a thin layer of cells in the epidermis. Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer...

 and stratum corneum

Stratum corneum

The stratum corneum is the outermost layer of the epidermis, consisting of dead cells that lack nuclei and organelles. The purpose of the stratum corneum is to form a barrier to protect underlying tissue from infection, dehydration, chemicals and mechanical stress...

 layers, it is composed of three to five layers of dead, flattened keratinocytes. The keratinocytes of the stratum lucidum do not feature distinct boundaries and are filled with eleidin

Eleidin

Eleidin is clear intracellular protein which is present in the stratum lucidum of the skin.Eleidin is a transformation product of the amino acid complex keratohyalin, the lifeless matter deposited in form of minute granules within the protoplasm of living cells. Eleidin is then converted to keratin...

, an intermediate form of keratin

Keratin

Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...

.

The thickness of the lucidum is controlled by the rate of mitosis of the epidermal cells. In addition, melanocytes determine the darkness of the stratum lucidum. The cells of the stratum lucidum are flattened and contain an oily substance that is the result of exocytosis of lamellar bodies

Lamellar bodies

Lamellar granules are secretory organelles found in type II pneumocytes and keratinocytes. They are oblong structures, appearing about 300-400 nm in width and 100-150 nm in length in transmission electron microscopy images...

 accumulated while the keratinocytes are moving through the stratum spinosum

Stratum spinosum

The stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is also referred to as the "spinous" or "prickle-cell" layer. This appearance is due to desmosomal connections of adjacent cells. Keratinization begins in the stratum spinosum....

and stratum granulosum.