folding of heart tube

Last reviewed 01/2018

Once formed, the heart tube elongates at a rate that is greater than the surrounding primitive pericardial cavity can accommodate. Consequently, from day 22 onwards the:

  • cephalic end of the tube is displaced ventrally, caudally and to the right
  • caudal end of the tube is displaced dorsally, ventrally and to the left

Simultaneously, individual regions of the tube are expanding and differentiating such that by the end of folding:

  • the region of the future atria lies craniodorsal to the future ventricular region
  • the primitive right and left atria lie dorsolateral to the primitive right ventricular outflow tract

Folding is complete by day 28.