Development of the gastro-oesophageal region during the human embryonic and foetal period. New contributions

Eight human embryos and thirteen human foetuses (8.1 mm-190 mm V-C) were studied. Two elements of the gastro-oesophageal region were studied with special emphasis: first, the relationship of the transformations of the right pneumato-enteric cavity with the gastro-oesophageal junction, and second, the enteric muscular stratum. From stage XVII (12.5 mm) the right pneumato-enteric cavity is separated from the rest of the bursa omentalis by the right pillar of the hiatus oesophagicus of the diaphragm. Three muscular layers were observed in the distal oesophagus of all the foetuses studied. The most superficial layer proceeds from fibres which are exterior to the profound layer. In the foetus of 71 mm a decussation between the exteriorized fibres of the ventral and dorsal oesophageal walls was observed at the gastro-oesophageal junction level, continuing in the middle layer of the stomach (foetuses of 36.5 mm to 71 mm). The phreno-oesophageal membrane is formed during the foetal stage by differentiation of the hiatal peri-oesophageal mesenchyme. The gastrophrenic ligament is the gastric portion of the fascia of the transcavitary oesophago-gastro-pancreato-splenic parietal coalescence.