ABSTRACT
Ablation of postotic somites 6– 13 on one side in embryos of Emys orbicularis L. or injury to the adjacent somatopleure at the developmental stage when 15– 21 somite pairs were present, led to arrest of forelimb-bud development in this part of the somatopleure on the operated side. Limb development in the remaining part of prospective somatopleure on the operated side was investigated 5– 11 days after the operation.
When this part of somatopleure was adjacent to cranial somites 6– 9 or 6-10, the development stopped at the start of the apical crest as in Anguis or Scelotes forelimb-buds. A part of somatopleure adjacent to caudal somites 8– 12, 9– 12 or 10– 12 developed into a normal limb with three segments; a part of somatopleure adjacent to 1– 2 somites only, developed into a reduced limb, scarcely swelling.
Each somitic level developed in relation to its initial regional determination dependent on position in the cephalocaudal axis; to its environment (cranial or caudal bud) and to the quantity of somatopleural material in the bud.
