NEW DATA ON THE EMBRYONIC-DEVELOPMENT OF THE LIMBS IN THE SLOW-WORM, ANGUIS-FRAGILIS LINNE 1758

Histological study and scanning electron microscopy show that the limb bud of young embryos of the slow-worm (Anguis fragilis L.) displays a segmental pattern. This metameric configuration is due to the presenc e, in the limb bud, of somitic processes which liberate cells into the bud and induce, in front of their distal end, the formation of locali zed thickenings of the ectoderm. After the formation of the main limb bud, outgrowths of transient existence develop in front of the process es of the somites, S6, S7 and S10 (S1 being the first post-otic somite ); several observations lead to homologize these accessory outgrowths to rudimentary, belatedly formed and soon abortive, digital anlagen; t he fact that somites are involved in their formation and are responsib le for the metameric pattern of the limb bud lead to the likely hypoth esis of a control, by the somites of the limb, of the number and of th e position of the digits in hands and feet.