Figure 3

Pax3 expression profiles in the embryonic superior colliculus of Pax7 mutant and wildtype mice. Comparative Pax3 embryonic expression profiles in wildtype (a,b,c,e,g,i,k) and Pax7 mutant mice (d,f,h,j,l). Note the decreased intensity of Pax3 in the rostral region (a) relative to the caudal region (b) of the ventricular/subventricular zones at E12.5, and lack of immunoreactivity within the intermediate zone. At E15.5, Pax3⁺ cells are present in the hindbrain in wildtype mice (c, e [inset from c]) but are spatially expanded in Pax7 mutant mice (d,f [inset from d]). (Arrows denote spatial extent of expression). At the rostral mesencephalon at this timepoint there are increased numbers of Pax3⁺ cells in Pax7^-/- mice relative to wildtype (g-h) together with expanded expression at the ventral ventricular surface (j), whereas Pax3 immunoreactivity was only detected in the dorsal ventricular region in wildtype mice (i). Consequently, at E18.5, whilst Pax3⁺ cells can be clearly detected in the ventricular zone of wildtype mice (k) they are no longer present in Pax7^-/- mice (l). Abbrev. IZ, intermediate zone; VZ/SVZ, ventricular zone/subventricular zone. Scale bar: a-b, i-l 100 μm; c-d 500 μm; e-h 200 μm.