Figure 5

Infiltration of externally applied molecules into the upper SC, but not the mid SC.

(a, b) Representative positive-ion micrographs of skin sections of mouse tails after soaking in water for 15 min (a) and after 30 min followed by soaking in 0.1 M KCl solution for 15 min (b). Schematic representation of the analyzed area is shown on the right. Scale bars, 50 μm. (c, d) Line scan data for each ion signal for the areas in (a) and (b), respectively, overlaid on the image of arginine/K. The three distinct layers of the SC are illustrated by three colors (purple, green and yellow) from outside inward. The average signal count for each area is shown on the right. Arrows indicate the washout and reappearance of K in the upper SC. (e) Representative positive-ion micrographs of skin sections of mouse tails after soaking in 0.03 M fluorescein/0.3 M K₂Cr₂O₇ water solution for 45 min. The m/z peaks of Cr and fluorescein are defined in Supplementary Figs 6 and 7, respectively. Schematic representation of the analyzed area is shown on the right. Scale bar, 50 μm. (f) Line scan data for Na, K, arginine, ceramide, fluorescein and Cr(VI) from the area in (e) overlaid on the images of Na/K and fluorescein/arginine. The three distinct layers of the SC are illustrated in three colors (purple, green and yellow). The average signal count for each area is shown on the right. Images in a–f are representative of three mice, for each of which at least three tail sections were investigated.