Apical Domain of the Epithelium

**Semantic type:** Anatomical Structure

**Definition:** The free part of the epithelium that faces the exterior surface or the lumen of an organ. It may contain cytoplasmic processes (microvilli, stereocilia, and cilia).

**Synonyms:** - Apical Domain of Epithelium - Free Surface of Epithelium - Free Surface of the Epithelium