Epidermal turnover is a conveyor: total renewal time is the sum of compartment residences. The viable epidermis and the stratum corneum share the same master gene (TP63), so the substrate predicts comparable phase dwell-times; calibrating the corneum transit to the cited ~14 days gives a total of ~28 days, inside the cited 28–40-day window.
Total turnover is the sum of compartment residences. Viable epidermis and stratum corneum share TP63, so the substrate gives them equal dwell; with the cited ~14-day corneum transit the total is ~28 days, inside the cited 28–40-day window.
Turnover is a conveyor, and conveyors add
Epidermal renewal moves a cell from the basal layer to the surface and off. The total turnover time is therefore a sum of compartment residence times, not a single rate — a fact long established by labelled-cell studies that add a viable-epidermis transit to a stratum-corneum transit.
The two compartments here share the same master gene, TP63, so the substrate assigns them the same dwell time (the dwell ratio is 1). That is a prediction, not a fit: equal γ gives equal substrate dwell.
One cited calibration sets the clock
With the stratum-corneum transit fixed to its cited value of 14 days, the equal-dwell viable phase is also 14 days, and the total epidermal turnover is 28 days. That lands inside the cited 28–40-day window for young-adult skin.
Ordering and grades
Because dwell grows with γ, the four organs rank in dwell as KRT14 > MITF > EDAR > TP63. The conveyor-sum structure is simulation-verified [V] Simulation-verified; the rate rests on one cited anchor [L] Cited anchor (the 14-day corneum transit). The absolute basal cycle time per cell is open [O] Open (obstacle stated): it needs a per-cell calibration.