Different fixative methods influence histological morphology and TUNEL staining in mouse testes.

Area of Science:

• Reproductive Toxicology
• Histopathology
• Apoptosis Research

Background:

• The Society of Toxicologic Pathology recommended modified Davidson's solution (mDF) for testicular fixation.
• Previous studies indicated mDF fixation can lead to false-positive TUNEL staining in testes.

Purpose of the Study:

• To compare the efficacy of different fixation methods on mouse testicular histology and TUNEL staining.
• To optimize testicular fixation protocols to minimize false-positive TUNEL staining while preserving morphology.

Main Methods:

• Mouse testes were fixed using various durations of mDF alone and a combination of mDF and PFA (paraformaldehyde).
• Histological morphology and TUNEL staining (for apoptosis) were evaluated.
• Cadmium-induced germ cell apoptosis was examined using the optimized fixation method.

Main Results:

• Extended fixation in mDF (24-36h) improved morphology but significantly increased false-positive TUNEL staining.
• A sequential fixation of 6h mDF followed by 18h PFA (mDF/PFA) yielded superior morphology and minimal false-positive TUNEL staining.
• The mDF/PFA method effectively visualized cadmium-induced germ cell apoptosis.

Conclusions:

• The combined mDF/PFA fixation method offers improved testicular morphology and accurate TUNEL staining.
• This optimized protocol minimizes artifactual TUNEL positivity, crucial for reliable apoptosis assessment in toxicologic pathology.
• mDF/PFA fixation provides integrated morphologic details and reduces false positives in testicular studies.