Figure 1.

Morphology and physical barriers in the epidermis layers of skin. (1) Stratum disjunctum acts as a physical barrier that sheds and reforms at fixed intervals. (2) Stratum corneum lipids having mortar-like structure along with protein bricks make envelopes covering corneocytes, acting as physical barriers. (3) Denser and packed zones of the stratum corneum layer playing the role of a physical barrier. (4) Basal membrane at the interface of the epidermal and dermal layer that also behaves as a barrier for drug absorption.