Figure 3. Abnormal differentiation of the keratogenous zone in various mutant nails.

(A) Plasminogen activator inhibitor type 2 (PAI2) is normally expressed in the keratogenous zone of the wild type nails (A.a, arrow). Neither the expression pattern nor the level of PAI2 is changed in the keratogenous zone of any of mutants (A.b-d, arrows). (B) Krt33b is normally detected in the keratogenous zone (KZ) of wild type nails (B.a, a′, arrow). In Msx2 mutant, its expression is reduced (B.b, b′, arrow). Krt33b expression is still detectable in Foxn1 mutant nails but lower than that in Msx2 mutant nails (B.c, c′, arrow). In the double mutant nails, no Krt33b expression is detected (B.d, d′). Krt86 mRNAs are also detected in the keratogenous zone of wild type nails (B.e, e′, arrow). Its expression is reduced in Msx2 mutants (B.f, f′, arrow), but not detectable in either Foxn1 mutant (B.g, g′) or double mutant nails (B.h, h′). In (B), a′-d′ and e′-h′ are higher magnifications of boxes in a-d and e-h, respectively. Black and White dashed lines demarcate the border between epithelial structures and the underlying mesenchyme. Digit 3 from the hind limbs is used for this assay. In all panels, the nail tips are orientated towards the left side.