Neuropil vacuolation in brain: a reproducible histological processing artefact

Area of Science:

• Veterinary Pathology
• Histotechnology
• Animal Diagnostics

Background:

• Vacuolation in animal brain tissue submitted for diagnostic histopathology has been observed.
• This vacuolation primarily affects white matter and can be mistaken for pathological conditions like intramyelinic edema.
• The cause was suspected to be related to tissue processing methods.

Purpose of the Study:

• To identify the cause of vacuolation artifact in animal brain tissue.
• To investigate the role of prolonged alcohol fixation in automatic tissue processors.
• To determine if species differences influence susceptibility to this artifact.

Main Methods:

• Experimental fixation of calf and pig brains using an enclosed automatic tissue processor.
• Prolonged immersion of fixed tissue in 70% alcohol.
• Histopathological examination of processed brain tissues.

Main Results:

• Consistently reproduced vacuolation artifact in calf brains after prolonged 70% alcohol immersion.
• Pig brains did not exhibit the same degree of vacuolation, suggesting species-specific susceptibility.
• The extent of vacuolation was influenced by processor factors beyond simple alcohol immersion duration.

Conclusions:

• Vacuolation artifact in animal brains is linked to prolonged tissue holding in 70% alcohol within automatic processors.
• Calf brains are more susceptible than pig brains, indicating species differences.
• Artifact can be avoided by retaining tissue in the primary fixative, bypassing prolonged alcohol exposure.