Expression of CGRP mRNA based on in situ hybridization with an anti-sense (a-g, l-o) and a sense (h-k, t-w) probe in mouse heads at E 12.5 (a,e,h), E14.5 (b,f,i), E17.5 (c,g,j) and P1 (d,k) and tibias at E 12.5 (l,p,t), E14.5 (m,q,u), E17.5 (n,r,v) and P1 (o,s,w). The CGRP reaction was localized in (c) and (g) (arrowheads); the CGRP reaction was scattered in (f,r,s) (arrowheads). e) Magnification of the squared region in (a); f) magnification of the squared region in b); g) magnification of the squared region in (c); p) magnification of the squared region in (l); q) magnification of the squared region in (m); r) magnification of the squared region in (n); s) magnification of the squared region in (o). Mad, mandible; B T, bone trabecula-like matrices; MC, Meckel’s cartilage; DG; dental germ; TI, tibia; HC, hyaline cartilage. Scale bars: 100 µm. a-d, h-o, t-w) magnification: 10x; e-g, p-s) magnification: 40x.