GENERAL HISTOLOGY

Detailed explanation-1: -In many tissues, the apical surface of the cell faces towards the external environment whereas the basolateral surface sits adjacent to an internal-facing basement membrane.

Detailed explanation-2: -In many epithelia, the apical surface is specialized. For instance, in the small intestine, the apical plasma membrane is folded into microvilli (see below) to increase the surface area for absorption of nutrients. Every epithelium has a basement membrane, that binds the epithelium to the underlying connective tissue.

Detailed explanation-3: -The apical surface of epithelial cells, which lines the lumen of sac-and tube-shaped organs and the inner surfaces of the body cavities, forms the interface between the extracellular milieu and underlying tissues.