Morphologic considerations in the interpretation of gastrointestinal disorders

Area of Science:

• Veterinary Pathology
• Gastrointestinal Histology
• Comparative Anatomy

Background:

• Gastrointestinal (GI) histopathology is prone to misinterpretation due to sampling errors and fixation artifacts.
• Normal variations in GI morphology differ significantly across species and intestinal segments.
• Postmortem delay and improper tissue handling can lead to significant cellular and architectural distortion.

Purpose of the Study:

• To outline common pitfalls in gastrointestinal sampling and interpretation.
• To emphasize the importance of species-specific knowledge for accurate histopathological diagnosis.
• To provide guidelines for optimal tissue fixation and preservation of intestinal morphology.

Main Methods:

• Review of common artifacts encountered in gastrointestinal biopsies and necropsies.
• Discussion of species-specific variations in villous morphology, cell populations, and architectural features.
• Recommendations for tissue processing, including fixation techniques, osmolarity, and handling procedures.

Main Results:

• Sampling errors, such as misidentification of intestinal segments (ileum vs. jejunum) or biopsy artifacts, can mimic disease states.
• Postmortem changes, particularly villous epithelial separation, occur rapidly (5-10 minutes) without prompt fixation.
• Optimal preservation involves opening, stretching, and pinning intestinal segments before fixation in iso-osmolar buffered solutions.

Conclusions:

• Minimizing sampling errors and artifacts through careful technique and species-specific knowledge is essential for accurate GI histopathology.
• Proper and timely tissue fixation is critical to prevent postmortem degradation and preserve normal morphology.
• Adherence to recommended fixation and processing protocols ensures reliable diagnostic interpretation of intestinal tissues.