Novel techniques for the estimation of intracorneal cohesion in vivo

Desquamation is the result of loss of cohesion between horny squames. This study is concerned with the in vivo measurement of intracorneal cohesion using three new techniques. A new instrument, the cohesograph, directly measures the force (g) required to distract a known area of partial thickness of stratum corneum in vivo. Sex and site differences were detected with this method. A surfometer was employed to measure the surface contours of the internal face of skin surface biopsies and when this measurement of the surface irregularity was compared to the 'cohesograph' reading for the same sites in 16 normal individuals a significant positive correlation of r=0-79 was found between the two sets of results. It is therefore suggested that the surfometer provides indirect measure of horny layer cohesion. Desquamation has also been estimated by using a modified 'scrub technique'. The scrub apparatus used is able to deliver a controlled stimulus to the skin surface to release horny cells. The light absorbance at 400 nm of corneocyte suspensions was measured and found to correlate well (r=0-96) with the numbers of squames released. It is suggested that the three techniques used in conjunction provide a profile of stratum corneum cohesion in vivo.