What type of epithelium forms the epidermis, and what is its key feature?

• A. Simple squamous epithelium; diffusion
• B. Stratified squamous keratinized epithelium; keratinized surface provides protection and waterproofing
• C. Stratified cuboidal epithelium; secretion
• D. Pseudostratified ciliated epithelium; mucus movement

Answer: (B)

The epidermis is formed by stratified squamous keratinized epithelium. Its key feature is the keratinized surface, where keratinocytes become filled with keratin as they migrate outward and eventually form the stratum corneum of dead, flattened cells. This keratinized layer provides strong protection against mechanical abrasion and acts as a waterproof barrier, preventing water loss from the body. The basal layer continually divides to replace cells that move upward and keratinize, while other epithelial types lack this multi-layered, keratinized surface and thus don’t confer the same protective waterproofing.