The mesenchymal factor, FGF10, initiates and maintains the outgrowth of the chick limb bud through interaction with FGF8, an apical ectodermal factor. - Ohuchi,H.; Nakagawa,T.; Yamamoto,A.; Araga,A.; Ohata,T.; Ishimaru,Y.; Yoshioka,H.; Kuwana,T.; Nohno,T.; Yamasaki,M.; Itoh,N.; Noji,S. (Development, 1997)