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Comprehensive and Detailed Explanation:

According to the ASCP HTL blueprint under Fixation (15–25%), glutaraldehyde is a strong cross-linking fixative ideal for electron microscopy due to superior ultrastructural preservation. However, its main disadvantages are slow penetration and tendency to over-harden tissues, making it unsuitable for routine large specimens or light microscopy. HTL candidates must understand fixative selection based on downstream applications. Proper use requires knowledge of concentration (usually 2.5%), pH, and post-fixation rinsing. Over-fixation with glutaraldehyde can mask antigens for IHC, requiring strong retrieval methods. Quality control includes monitoring fixation time and avoiding use on specimens thicker than 2 mm. This concept helps technologists choose the right fixative to prevent artifacts and ensure compatibility with processing, embedding, microtomy, and staining. Understanding these principles is critical for producing high-quality diagnostic slides.