Fig. 6. Comparison of skin and hair follicle development between wild-type and Ta mutant embryos. (A,B) At E11, the ectoderm appears slightly thinner in Ta skin. (C,D) At E15, the first wave hair follicles (tylotrich or guard) are seen in wild-type skin whereas the Ta skin ectoderm is uniformly thin and devoid of hair placodes. (E,F) At E17, tylotrich hair follicles have developed into stage 3-4 in wild-type skin. Placodes of awl follicles (stage 1-2) have appeared in Ta skin (arrow) and the epidermis has increased in thickness. (G,H) At P0 (newborn), tylotrich (skeleton arrow) and awl follicles (arrow) are present in wild-type skin, whereas in Ta mice only awl follicles are seen. (I-N) Differentiation of the keratinocytes is not affected in Ta skin. (I,J) Keratin 14 is expressed in basal epithelial cells. (K,L) Keratin 10 is expressed in suprabasal cells. (M,N) Filaggrin (FIL) is expressed in differentiated keratinocytes. Broken lines indicate the interface between epithelium and mesenchyme. Scale bar: 100 µm.