SOAP-INDUCED WINTER XEROSIS 209 A D Figure 1. Electron micrographs of tape strippings of normal skin (grade 1). Degradation of desmosomes toward the surface of the stratum corneum: A. First strip desmosome fully degraded. B. Second strip desmosome partially degraded and encapsulated by lipid lamellae. C. Second strip desmosome partially degraded, vacuolation of structure. D. Third strip normal desmosome lipid envelopes in direct contact with desmosome. (x200,000 Bar 0.05 •m). stratum corneum (Table III). Furthermore, the relative levels of the different ceramide sub-species were unchanged with depth (data not shown). Of the other lipid species investigated, the relative and mass amounts of fatty acids also tended to increase in the outer layers of the stratum corneum, but these were not statistically significant. Cho- lesterol levels were significantly increased in outer, compared with inner, stratum corneum of xerosis grade 4 (p 0.05). Significant correlations were also seen for the

210 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 2. Electron micrographs of tape strippings of subjects with severe xerosis (grade 4): Persistence of desmosomes in outermost layers of the stratum corneum. First tape stripping from two subjects (A,B). (X200,000 Bar 0.05 Ixm). inner tape strippings between skin xerosis and percentage levels of fatty acids, together with skin xerosis and percentage levels of ceramides (R = + 0.45, p = 0.046 R = -0.45, p = 0.049, respectively). STRATUM CORNEUM DESMOGLEIN I ANALYSIS Figure 5 compares the differences in desmoglein 1 levels in stratum corneum of subjects with normal (grade 1) and xerotic skin (grade 4) conditions. Compared with normal skin, statistically significant increases in desmoglein 1 levels were observed. DISCUSSION An understanding of the composition and structure of the surface layers of the stratum corneum is particularly important, as it is this region of the tissue where skin dryness