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Epidermis


/ˌepiˈdərmis/

Noun, pl. epidermides

1. The outermost and nonvascular layer of the skin, derived from the embryonic ectoderm, varying in thickness from 0.07–1.4 mm. On the palmar and plantar surfaces it comprises, from within outward, five layers: (1) basal layer (stratum basale), composed of columnar cells arranged perpendicularly; (2) prickle cell or spinous layer (stratum spinosum), composed of flattened polyhedral cells with short processes or spines; (3) granular layer (stratum granulosum) composed of flattened granular cells; (4) clear layer (stratum lucidum), composed of several layers of clear, transparent cells in which the nuclei are indistinct or absent; and (5) horny layer (stratum corneum), composed of flattened, cornified, non-nucleated cells. In the epidermis of the general body surface, the clear layer is usually absent. (Dorland’s Medical Dictionary for Health Consumers)

2. The outer, protective layer of the skin of vertebrates, covering the dermis. (wiktionary.org)

3. The similar outer layer of cells in invertebrates and plants. (wiktionary.org)

4. The outer layer of tissue in a plant, except where it is replaced by periderm. (Google Dictionary)

Word origin: From Latin epidermis, from Ancient Greek ἐπιδερμίς (epidermis) (ἐπί, on top of) + dermis (< δέρμα(derma), skin)


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