Desquamation is the normal process in which corneocytes are progressively lost at the surface of the stratum corneum.  The main step of this process involves the enzymatic degradation of the corneodesmosome, a protein complex responsible for the cell-to-cell cohesion of the corneocytes.  The extent of desquamation can be quantified by measuring the amount of corneocytes that are released from the surface of the stratum corneum using human skin tissue equivalents as the model.  For this process, corneocytes are recovered from the surface of the tissue via sonication, and treated with SDS at a high temperature to convert them into cornified envelopes, which are primarily composed of cross-linked proteins.  The cornified envelopes can then be indirectly quantified by first immobilizing them on a PVDF membrane and then treating the PVDF membrane with a dye that binds to proteins.  With this assay, the dye intensity will be proportional to the number of cornified envelopes, which in turn will be in proportion to the extent of desquamation.  For statistical purposes, the dye intensity can be quantified via densitometry.  In addition, the efficacy of the desquamation agent can be assessed via histology (see below).