Please note that this explanation may not be the actual physics definition, but it will help you to understand the concept of ‘refractile’ cell morphology.....
From the statement below by www.brittanica.com it appears that light is both partially reflected by & partially refracted or "transmitted" (think absorbed) into the object it is hitting. (Technically transmission is NOT absorption, but for this purpose it's easier to think of it as being absorbed by the cell/cell parts).
So when light hits the cells/cellular parts in a scan, some of the light is reflected back and some of the light is "absorbed" by the cell/cell parts. The amount of light "absorbed" is variable for each cellular component, and therefore, the amount of light reflected back is also variable.
In the scan or microscope, we actually "see" the reflected light. Not the refracted (absorbed) light and because the light reflected is variable, we are able to "see" the different components of the cell (i.e the different amounts of light reflected by the various parts).
So the statement ‘refractile’ cell morphology means that the cell has components which absorbs light at variable amounts and therefore, also reflects light at different amounts. Essentially, you are able to "see" the cell morphology & its differences because it refracts (absorbs) some light and reflects the rest.
Hope this helps get the concept. =)
"When a ray of light is incident upon a plane surface separating two mediums (e.g., air and glass), it is partly reflected (thrown back into the original medium) and partly refracted (transmitted into the other medium)."