Abstract
Purpose
An entire fascial configuration at the esophageal hiatus might not be demonstrated histologically. According to observations of human fetus histology, the aim of this study was to consider which factor is likely to make the individual variation in adults.
Methods
We observed frontal histological sections containing the esophageal hiatus from 12 midterm fetuses at 12–16 weeks (crown-rump length:CRL, 85–137 mm) and 10 near-term fetuses at 26–30 weeks (CRL, 214–250 mm).
Results
At midterm, the inferior fascia of diaphragm turned upward to join the adventitia of the esophagus, but the superior fascia was underdeveloped. At near-term, both the inferior and superior fasciae often joined the adventitia in the left side but not in the right side. Fascial development advanced in the left side of the hiatus. The pleural recess as well as the upward protruding right crus of diaphragm was likely to disturb the fascial connection especially in the superior side. The foregut-midgut junction, suggested with cytokeratin 5/6 immunostaining, was located in the hiatus.
Conclusion
The phreno-esophageal membrane, interposed between the superior and inferior fasciae of diaphragm and the adventitia of esophagus, seemed to be established first in the left side at near-term. The delayed growth in the right side might connect to individual differences in adults.