1. In the developing tail-bud of urodele larvae, the neural and the mesodermal components of the tail fold along their boundary and surround the caudal extremity of the notochord.

  2. The first growth of the tail-bud is brought about by an autonomous lengthening of the neural and the mesodermal tissues.

  3. The notochord does not have an active part in the process of the lengthening of the tail, but plays a passive role. It is a supporting organ, acting as a splint. In this way it determines the ultimate length of the tail.

  4. It is not the notochord, but the combination of the neural and the mesodermal tissues, which in the first place determines the direction in which the tail grows.

You do not currently have access to this content.