Development of the interatrial wall during the ontogenesis of foetuses and children up to 1 year of age

Background . The foramen ovale, present in foetal interatrial septum, plays an important role during foetal life. During delivery, foramen ovale closes and becomes fossa ovalis, starting the pulmonary circulation. The aim of our study was to describe the growth of the interatrial wall and changes in location of the foramen ovale, and fossa ovalis during the ontogenesis in the human hearts. M ethods. The study was performed on post-mortem material obtained from 92 human hearts from 22 nd week of foetal life up to 1 year of age, fixed in a 4% formalin solution. Results . The interatrial wall size in the studied development period was greater in the horizontal than in the vertical dimension. During ontogenesis up to one year old, the anterior and inferior parts of the interatrial wall, increased their shares considerably by 8% and 6%, respectively. The percentage participation of foramen ovale in the interatrial wall construction in the foetal period, formed more than 50% of its size and fairly decreased reaching in infants about 39%. Conclusions. Our study demonstrated that during ontogenesis, from the foetal period to infancy, the parts of the interatrial wall increase their dimensions unevenly. The foramen ovale growth is smaller, compare to the rest of the interatrial wall development. On the basis of our data we can assume that the foramen ovale center tends to be found in the postero-inferior quadrant of the interatrial wall (foetuses) and in postero-superior quadrant of the interatrial wall - in infants.