American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

What is the best practice for avoiding ghost-like, pale chromosomes during staining?

1. Increase trypsin time

2. Use a higher concentration of stain

3. Decrease trypsin time

4. Reduce the staining time

The correct answer is: Decrease trypsin time

Decreasing the trypsin time is the best practice for avoiding ghost-like, pale chromosomes during staining. When trypsin, an enzyme used in the preparation of metaphase chromosomes from cell culture, acts for too long, it can overly degrade the chromatin. This results in chromosomes that are faintly stained or appear ghost-like because the structural integrity and chromatin organization are compromised. By reducing the trypsin time, you allow for a more optimal condition where the chromosomes maintain their integrity and take up the stain more effectively, leading to clearer, more distinct banding patterns. This fine balance in trypsinization is crucial for effective cytogenetic analysis, as it directly impacts the visibility and interpretability of chromosomal features. Additionally, while increasing the concentration of stain or staining for a longer period might seem beneficial for enhancing visibility, these methods do not address the underlying issue of chromosome preparation. Over-staining can also lead to excessive background or obscure details, and varying the concentration of stain might not compensate for the loss of chromosome quality due to prolonged trypsin digestion.