The organization of human epidermis: functional epidermal units and phi proportionality.

摘要: The concept that mammalian epidermis is structurally organized into functional epidermal units has been proposed on the basis of stratum corneum (SC) architecture, proliferation kinetics, melanocyte:keratinocyte ratios (1:36), and, more recently, Langerhans cell: cell (1:53). This article examines in human skin which maintenance phi (1.618034) proportionality provides a central organizing principle. following empirical measurements were used: 75,346 nucleated cells per mm 2 , 1394 1999 melanocytes 16 layers, 900-μm corneocyte surface area, 17,778 corneocytes 14-d turnover time, and 93,124 total cells. Given these data: (1) number mean proportional between sum + melanocyte populations cells, 3393/17,778–17,778/93,124; (2) ratio over proportional, 75,346/17,778∼phi 3 ; (3) assuming similar times for Malpighian epidermis, results from subtraction cellular fraction equal to ∼2/phi ×the living 75,436 – (2/phi ×75,346) ∼17,778; (4) if time equals time×the living/dead then compartmental are unequal (14 d 45.3 ∼1/2phi) replacement rates 52.9 corneocytes/69.3 keratinocytes h . These empirically derived equivalences provide logicomathematical support presence skin. Validation unit architecture will be important tissue engineering design instruments measurement.