Structure stratum corneum

P. M. Elias, E. R. Cooper, A. Korc, and B. E. Brown. Percutaneous transport in relation to stratum corneum structure and lipid composition. J. Invest. Dermatol. 76 297-301 (1981). 

All the above-mentioned changes in lipid composition and organization in diseased and dry skin likely contribute to an impaired stratum corneum barrier function and increased susceptibility to dry skin. However, as previously indicated, abnormalities in the process of envelope formation may also strongly influence the stratum corneum barrier integrity. Therefore, more information is required to elucidate the precise mechanisms by which stratum corneum structure and function are altered. 

Ghadially, R., J.T. Reed, and P.M. Elias. 1996. Stratum corneum structure and function correlates with phenotype in psoriasis. JInvest Dermatol 107 558. 

Rawlings, A.Y., et al. 1994. Abnormalities in stratum corneum structure, lipid composition, and desmosome degradation in soap-induced winter xerosis. J Soc Cosmet Chem 45 203. 

Graaff, A.M., et al. 2003. Combined chemical and electrical enhancement modulates stratum corneum structure. J Control Release 90 49. 

Harding, C.R., The stratum corneum structure and function in health and disease, Dermatol. Then 17 (Suppl. 1), 6-15,2004. 

Ghadially, R., Halkier-Sorensen, L., and Elias, P.M., Effects of petrolatum on stratum corneum structure and function, J. Am. Acad. Dermatol., 26, 387, 1992. 

Stratum Corneum Structure. Reviewers agree that for most compounds the rate-limiting barrier properties of skin are located within the SC (2, 10, 12, 15, 16, 21), The texture and cohesiveness of this tissue are familiar to anyone who has ever peeled bits of it from sunburned skin large sheets of SC can be separated from skin (2). Such sheets look like used polyethylene film, and their resistance to water diffusion approximates that of Mylar film of similar thickness (16). However, each sheet is a mosaic made of individual cells (2). 

Suhonen, T.M. Bouwstra, J.A. Urti, A. Chemical enhancement of percutaneous absorption in relation to stratum corneum structural alterations. J. Controlled Release 1999, 59, 149-161. 

Aszterbaum, M., G. K. Menon, K. R. Feingold, and M. L. Williams. 1992. Ontogeny of the epidermal barrier to water loss in the rat Correlation of function with stratum corneum structure and lipid content. Pediatr. Res. 31 308-317. 

An important aspect of enhanced transdermal transport is that it is often accompanied by irritation. This irritation is likely to be due to the disruption of the stratum corneum structure. It is important to note, however, that the composition of an applied multicomponent formulation, specifically that of a microemulsion, changes over time... 

This result has two implications from the point of view of skin care. First, the evaporation rate is significantly reduced when liquid crystals appear in the formulation during evaporation, as demonstrated by Moaddel and Friberg [37] and Langlois and Friberg [38]. The importance of slow evaporation to retain as much water as possible is obvious for skin care products. In addition, as recently demonstrated by Bodde et al. [39], the liquid crystals serve to reduce the evaporative water loss from the skin, an essential function. Finally, the publication from the Elias group [40] demonstrates that a combination of compounds that produce a lamellar structure actually will heal damaged stratum corneum structures. 

The present daily approach to skin care formulations is based on an assumed relation between the original composition and the final activity of the product. So a significant number of authors have tied to relate the size of liposomes in a solution to the final action of an active substance. The results [48,49] have given ample proof that such a relation does not exist. The reason for this lack of success is obvious. Within 25 min after application, 90-95% of the water in a formulation operates, and the new structures appearing during this process cannot a priori be related to the original structures. The biological activity of the formulation depends on the final structure and its interaction with the stratum corneum structural units. Hence, the activity of the formulation depends on the structures found in the water-poor parts of the system as shown in Fig. 5. 

Differentiated cells Intercelluar region Layered structure Fig. 1.1 Schematic representation of the stratum corneum structure. 

---