layers: stratum corneum (horny layer; dead keratinized cells; protects deeper cells from environment, prevents water loss, protects from abrasion and penetration; barrier against biological, physical, and chemical assaults), lucidum (only in thick skin, such as palms or soles; clear layer; thin translucent band of 2/3 rows of clear-flat-keratinized dead cells), granulosum (granular layer; 4-6 flattened cells thick, where keratinization begins; slows water loss) spinosum (prickly layer; several cells thick; keratinocytes in this layer appear spikey - prickle cells) basale (deepest layer; firmly attached to dermis; single row of mitotic cells - actively dividing)