1. Basal layer (stratum basale): Mitotically active keratinocytes with less abundant cytoplasm, arranged in a palisade pattern (similar Cto a fence).

2. Spinous layer (stratum spinosum): Larger keratinocytes than those in the basal layer; composed of several layers of keratinocytes attached to one another by intercellular bridges (desmosomes). These bridges are highlighted by the presence of intercellular edema (spongiosis). Loss of these connections results in acantholysis. As keratinocytes mature toward the surface, increased keratin content is observed.

3. Granular layer (stratum granulosum): Composed of 1 to 3 layers of flattened keratinocytes that contain basophilic keratohyalin granules in their cytoplasm.

4. Stratum corneum: Composed of dead cells called corneocytes, this is the final stage in epidermal maturation.These keratinocytes have lost their nuclei and have high keratin content.Hyperkeratosis refers to thickening of the stratum corneum. There are two types: Parakeratotic hyperkeratosis: nuclei are retained in corneocytes. Orthokeratotic hyperkeratosis: nuclei are lost

Stratum corneum

Clear or translucent layer (stratum lucidum): A homogenous eosinophilic layer found exclusively on palmar and plantar skin, located between the stratum corneum and the granular layer.

Granular layer

Spinous layer

Granular layer: 1 to 3 layers of flattened keratinocytes that contain basophilic keratohyalin granules in their cytoplasm

Increased melanin in the basal layer seen in individuals with darker phototypes

Increased melanin in the basal layer seen in individuals with darker phototypes