Rroni’s honestly significant difference post-hoc tests. Student t-test was performed when only two groups were compared. P,0.05 was considered statistically significant. All data are presented as average with error bars indicating the standard error of the mean.Results Tgfb3 is Expressed in the Upper Layers of the Epidermis Throughout the Wound Epigenetic Reader Domain healing 25033180 ProcessDespite the report of the expression of TGF-? throughout the epidermis [15,22], we failed to detect the presence of Tgfb3 using commercially available antibody on tissue from murine wounds. Alternatively, we took advantage of a new Tgfb3-Cre knock-in allele [27,31] and crossed it with the R26R-LacZ reporter mouse [32]. X-gal staining showed strong LacZ expression in the upper layers of the epidermis (Figure 2a , close-up in g), as well as in hair follicle (Figure 2f) and sebaceous gland as previously reported [31]. This pattern of expression is similar to the expression of Crerecombinase as previously described [31]. During wound healing, X-gal was detected in suprabasal layers of the Epigenetic Reader Domain migrating keratinocytes 4 days post-wounding (Figure 2a), while it was restricted to the superficial layers of the newly formed epidermis 7 and 11 days post-wounding (Figure 2b, c). This staining was specific as transgene negative animals showed no X-gal positive signal (Figure 2e).Morphometric AnalysisSerial sectioning (7 mm thick) of each wound was performed. Several morphometric parameters were measured every 10 to 40 sections (d = distance between two sections) using NIH-ImageJ as shown in Figure 1: the length of the wound (l), the length of the epidermis (le), the area of the epidermis (ae) and the area of the granulation tissue (aw). From these measurements, other metrics were calculated: the overall epidermal area covering the wound (ea = sum of (le6d)), the overall wound area (wa = sum of (l6d)), the epidermal volume (ev = sum of (ae6d)) and the wound volume (wv = sum of (aw6d)). The percentage of closure was calculated as the ratio of epidermal area over wound area. The length of the epidermal migrating tongue (lmt) and the depth of the wounds were measured on three sections in the middle of the wound only and presented as average of the three measurements for each wound.ImmunostainingParaffin embedded sections were immunostained as previously described [28]. Primary antibodies were: mouse monoclonal against Proliferative 
Cell Nuclear Antigen (PCNA, Biomeda, Foster City, CA), alpha-smooth muscle actin (Sigma, St-Louis, MO), and beta-actin (Sigma); rabbit polyclonal against Interferon Regulator Factor 6 (Irf6 [29]). Secondary antibodies were: goat anti-mouse FITC (Sigma), and goat anti-rabbit Alexa 568 (Molecular Probes, Grand Island, NY). Nuclear DNA was labeledThe Absence of TGF-? Impairs Wound ClosureIn order to assess the requirement for TGF-? during wound healing, we performed excisional wounds on the back of wild type mice and followed their healing over an 11-day period 16574785 (Figure 3). We used macroscopic photomicrographs as a first indicator of wound healing. Four days post-wounding, healing was engaged with the presence of scab and redness in the wound. TGF-? treated and control wounds (saline injected and TGF-?+NABTGFB3 and Wound HealingFigure 1. Schematic of the morphometric analysis. l = length of the wound (blue solid line); le = length of the epidermis (yellow solid line); ae = area of the epidermis (black dotted line); aw = area of the granulation tissue (green solid line); wd = wou.Rroni’s honestly significant difference post-hoc tests. Student t-test was performed when only two groups were compared. P,0.05 was considered statistically significant. All data are presented as average with error bars indicating the standard error of the mean.Results Tgfb3 is Expressed in the Upper Layers of the Epidermis Throughout the Wound Healing 25033180 ProcessDespite the report of the expression of TGF-? throughout the epidermis [15,22], we failed to detect the presence of Tgfb3 using commercially available antibody on tissue from murine wounds. Alternatively, we took advantage of a new Tgfb3-Cre knock-in allele [27,31] and crossed it with the R26R-LacZ reporter mouse [32]. X-gal staining showed strong LacZ expression in the upper layers of the epidermis (Figure 2a , close-up in g), as well as in hair follicle (Figure 2f) and sebaceous gland as previously reported [31]. This pattern of expression is similar to the expression of Crerecombinase as previously described [31]. During wound healing, X-gal was detected in suprabasal layers of the migrating keratinocytes 4 days post-wounding (Figure 2a), while it was restricted to the superficial layers of the newly formed epidermis 7 and 11 days post-wounding (Figure 2b, c). This staining was specific as transgene negative animals showed no X-gal positive signal (Figure 2e).Morphometric AnalysisSerial sectioning (7 mm thick) of each wound was performed. Several morphometric parameters were measured every 10 to 40 sections (d = distance between two sections) using NIH-ImageJ as shown in Figure 1: the length of the 
wound (l), the length of the epidermis (le), the area of the epidermis (ae) and the area of the granulation tissue (aw). From these measurements, other metrics were calculated: the overall epidermal area covering the wound (ea = sum of (le6d)), the overall wound area (wa = sum of (l6d)), the epidermal volume (ev = sum of (ae6d)) and the wound volume (wv = sum of (aw6d)). The percentage of closure was calculated as the ratio of epidermal area over wound area. The length of the epidermal migrating tongue (lmt) and the depth of the wounds were measured on three sections in the middle of the wound only and presented as average of the three measurements for each wound.ImmunostainingParaffin embedded sections were immunostained as previously described [28]. Primary antibodies were: mouse monoclonal against Proliferative Cell Nuclear Antigen (PCNA, Biomeda, Foster City, CA), alpha-smooth muscle actin (Sigma, St-Louis, MO), and beta-actin (Sigma); rabbit polyclonal against Interferon Regulator Factor 6 (Irf6 [29]). Secondary antibodies were: goat anti-mouse FITC (Sigma), and goat anti-rabbit Alexa 568 (Molecular Probes, Grand Island, NY). Nuclear DNA was labeledThe Absence of TGF-? Impairs Wound ClosureIn order to assess the requirement for TGF-? during wound healing, we performed excisional wounds on the back of wild type mice and followed their healing over an 11-day period 16574785 (Figure 3). We used macroscopic photomicrographs as a first indicator of wound healing. Four days post-wounding, healing was engaged with the presence of scab and redness in the wound. TGF-? treated and control wounds (saline injected and TGF-?+NABTGFB3 and Wound HealingFigure 1. Schematic of the morphometric analysis. l = length of the wound (blue solid line); le = length of the epidermis (yellow solid line); ae = area of the epidermis (black dotted line); aw = area of the granulation tissue (green solid line); wd = wou.