IN-VITRO RECONSTITUTION OF STRATUM-CORNEUM LIPID LAMELLAE

In the final stages of differentiation in the epidermis of terrestrial mammals, lipids are extruded into the intercellular spaces. The initi ally extruded lipid becomes transformed into broad, multilamellar shee ts that are found in the intercellular spaces throughout the stratum c orneum. These lamellae display an unusual alternating broad-narrow-bro ad pattern of lucent bands as revealed by transmission electron micros copy (TEM). This arrangement results in two periodicities that can be measured from electron micrographs and are also evident in X-ray diffr action-5 nm (broad) and 13 nm (broad-narrow-broad). The goal of the pr esent study was to reconstitute these lamellae in vitro. Porcine strat um corneum lipids were applied to Millipore filters. The disks were pl aced in water and heated to 80 degrees C for 1 h. After cooling, the d isks were stored over desiccant. At each stage, the disks were prepare d for TEM. TEM revealed that the application of the lipid solutions on to the disks resulted to deposition of mostly amorphous material. Heat ing in water resulted in the formation of many lamellae. The width of the lamellae was uniform and in the range of 5 to 6 nm with no broad-n arrow-broad pattern; however, after storage under desiccating conditio ns, the broad-narrow-broad pattern was reproduced. (C) 1998 Elsevier S cience B.V. All rights reserved.