Development of the stratum corneum

In 2015, Professor Ronald (Ronnie) Marks will celebrate his 80th birthday and the 35th year since assuming the Chair of Dermatology at the University of Wales College of Medicine in Cardiff, Wales. Ronnie's long and prolific career is well deserving of a celebratory Festschrift. Among his many accomplishments, Marks was an early champion of quantitative measurements and the application of bioengineering methods to clinical skin science, with particular focus on stratum corneum biology and the measurement of skin appearance. Appealing to Ronnie's wry sense of humour, I would characterize his career in the words of the native Welshman, Dylan Thomas, who published an unfinished novel in 1955 entitled Adventures in the Skin Trade. Ronnie Marks has been a quintessential and imaginative adventurer in the skin trade', and he continues to forge new trails for others to follow. The areas highlighted below are emblematic of Ronnie's varied research interests and his impact on stimulating experimental questions for me and future investigators of epidermal differentiation and stratum corneum development. What's already known about this topic? Stratum corneum (SC) development begins in utero under total aqueous immersion. Factors implicated in regulating SC intrauterine maturation include the hormonal milieu, nutrient gradients, amniotic fluid exposure, periderm disaggregation, and the production of vernix caseosa which overlays the developing SC in the 3rd trimester of human gestation. What does this study add? Advances in 3D/4D ultrasonography allow unprecedented visualization of fetal skin development. The standard two compartment brick and mortar' model of SC architecture is better expanded to three compartments using a molecular model in which i) the continuous lamellar hydrophobic lipid phase is separated from ii) discontinuous hydrophilic domains (corneocyte interiors) by iii) a singular, covalently cross-linked, amphipathic, multi-gene, polymeric molecule, the cornified envelope.