Fig. 1. Notch1 loss leads to reduced cell numbers in hair follicles but to an expansion in the number of epidermal keratinocytes. (A) ß-galactosidase (lacZ, green) immunohistochemistry on Msx2Cre;Notch1^flox/flox;Rosa26R/+ skin. Note that ß-galactosidase staining displays the area of Notch1 deletion. (B) Stereoscopic side view of anagen-deleted Notch1 (anN1; left) and embryo-deleted Notch1 (emN1; right) skin at 9 days of age (P9). (C) Stereoscopic view magnified from the images shown in B after dissection. Wild type, left (blue box); anN1, middle (yellow box); emN1, right (red box). Arrows indicate guard hairs. (D) Histological view of the follicles shown in B and C. The different genotypes are designated as in C. Nuclei were stained with DAPI. (E) Average number of hair matrix cells (below the red line in D) per hair follicle. ^*P<0.00001. Error bars represent s.d. (F,G) Hematoxylin and Eosin staining of P9 (F) and P453 (G) skin. Notice the epidermal hyperplasia in older emN1 skin (G). Scale bars: 50 µm in A; 300 µm in B; 200 µm in C; 20 µm in D; 40 µm in F,G.