Four layers of the epidermis

- stratum basale

• stem cells are here
• hemidesmosomes attach epidermis to dermis
• may contain melanocytes, Langerhans cells

- stratum spinosum

• prominent desmosomal intercellular attachments
• keratinocytes appear larger, flatter
• Langerhans cells typically found here

- stratum granulosum

• keratinocytes have keratohyalin granules w/in cytoplasm
• granules have profillagrin, which is cleaved into filaggrin. Filaggrin is the "filament aggregating protein" that acts to aggregate keratin filaments. It's important for formation of the stratum corneum.

- stratum corneum

• many layers of cornified cells (composed mostly of protein) that lack nuclei