Ultrastructural Changes of the Smooth Muscle in Esophageal Atresia

Abstract

Esophageal atresia (EA) with or without tracheo-esophageal fistula (TEF) is a relatively rare congenital anomaly. Despite the advances in the management techniques and neonatal intensive care, esophageal dysmotility remains a very common problem following EA/TEF repair. Our current study aimed to describe the most significant ultrastructural changes of the smooth muscle cells (SMCs) trying to highlight some of the underlying mechanisms of esophageal dysmotility following EA/TEF repair. Twenty-three biopsies were obtained from the tip of the lower esophageal pouch (LEP) of 23 patients during primary repair of EA/TEF. Light microscopic examination was performed with hematoxylin and eosin (HE), and Van Gieson's stains. Ultrastructural examination was done using transmission electron microscopy (TEM). Histopathological examination showed distortion of smooth muscle layer and deposition of an abundant amount of fibrous tissue in-between smooth muscles. Using TEM, SMCs exhibited loss of the cell-to-cell adhesion, mitochondrial vacuolation, formation of myelin figures, and apoptotic fragmentation. There were also plasmalemmal projections and formation of ghost bodies. Interestingly, SMCs were found extending pseudopodia-like projections around adjacent collagen fibers. Engulfed collagen fibers by SMCs underwent degradation within autophagic vacuoles. Degeneration of SMCs and deposition of abundant extracellular collagen fibers are prominent pathological changes in LEP of EA/TEF. These changes might contribute to the pathogenesis of esophageal dysmotility in patients who have survived EA/TEF.

How to Care for Patients with EA-TEF: The Known and the Unknown

“…In addition, there is abnormal development of the esophageal smooth muscle, with distorted smooth muscle tissue and tracheobronchial remnants found in the esophagus. [8] Structurally, EA patients, particularly those with long gap EA, can also lose some function of the anti-reflux barrier after surgical repair. In long gap atresia, gastric pull up causes the lower esophageal sphincter to no longer be overlapped by the crural diaphragm, weakens the phrenoesophageal ligament, decreases the angle of His, and creates a hiatal hernia.…”

Impedance Testing in Esophageal Atresia Patients

“…The increased risk of GERD in this group is due to both intrinsic dysmotility and structural factors. Primary dysmotility is a result of abnormal development of esophageal smooth muscle, with histopathologic features including distortion of smooth muscle, fibrous tissue in between smooth muscle layers (4), and tracheobronchial remnants present in the esophagus (5). In addition, there is abnormal congenital neural innervation of the esophagus, with a hypoplastic Auerbach plexus (6) and decreased interstitial cells of Cajal (7).…”