Megaoesophagus in rats: a clinical, pathological and morphometrical study

Area of Science:

• Veterinary Pathology
• Gastroenterology
• Animal Models

Background:

• Megaoesophagus is a condition characterized by abnormal dilation of the esophagus.
• Understanding the underlying mechanisms and potential causes of megaesophagus in animal models is crucial for comparative medicine.

Purpose of the Study:

• To investigate the clinical, radiographic, and histological features of megaesophagus in Long-Evans rats.
• To explore the potential aetiology of megaesophagus in this specific rat strain.

Main Methods:

• Clinical examination of 82 affected Long-Evans rats (aged 3-32 months).
• Radiographic imaging with barium contrast to assess esophageal structure.
• Histological examination of esophageal tissues, focusing on muscular layers and myenteric ganglia.
• Geometrical modeling to analyze esophageal shape and ganglion cell density.

Main Results:

• Affected rats exhibited clinical signs including coarse hair, neck distension, and respiratory distress.
• Radiography revealed esophageal dilation with impacted food, varying in severity.
• Histology showed inflammation and necrosis in muscular layers, reduced myenteric ganglion cells, and decreased muscle thickness.
• Geometrical analysis ruled out shape changes as the cause for reduced ganglion cell number.

Conclusions:

• Megaoesophagus in Long-Evans rats is associated with significant structural and cellular changes in the esophagus.
• The absence of infectious disease and strain specificity suggest a hereditary basis for this condition.
• This rat model provides insights into esophageal motility disorders and their genetic underpinnings.