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

For optimal resolution in imaging chromosomes, which objective lens is recommended?

1. An objective lens with an NA of 1.0 to 1.2

2. An objective lens with an NA of 1.3 to 1.4

3. A low power objective lens

4. An objective lens with no NA listed

The correct answer is: An objective lens with an NA of 1.3 to 1.4

For optimal resolution in imaging chromosomes, an objective lens with a numerical aperture (NA) of 1.3 to 1.4 is recommended. The numerical aperture is a crucial factor in microscopy that determines the lens's ability to gather light and resolve fine details in the specimen being observed. A higher NA allows for greater resolution, which is particularly important when imaging chromosomes as they are often small and require fine detail to identify structural anomalies effectively. Using an objective lens within the 1.3 to 1.4 range strikes a balance between gathering sufficient light for high-resolution images while also minimizing aberrations that can obscure details. This precision is essential for cytogenetic analysis, where accurately visualizing and differentiating between chromosomal features can significantly impact the interpretation of genetic material. Options with lower NA values would not provide the same level of clarity and detail, making them less suitable for examining chromosomes. Similarly, an objective lens that does not specify an NA would be uncertain in its capability, potentially leading to suboptimal imaging outcomes.