If they have a large round nucleus then they are dysplastic and will not transmit light. White areas are the dysplastic areas. The whiter the area the worse the dysplasia. Abnormal blood vessels can also be seen. Neoplasia means new growth.
New growth means new blood vessels.
Often these new blood vessels are abnormal. These abnormal vessels can be seen through the colposcope. The worse the vessels appear, the worse is the dysplasia. Cancers have the worst vascular appearance of all the changes that can occur on the cervix. During a colposcopic examination the first determination is if there are abnormal areas.