As seen in panel B , a portion of the stem cells of three crypts appear to have a mutation in MT - COI .
40 % to 50 % of the cells arising from those stem cells form a white segment in the cross-cut area .
As seen in panel B , a portion of the stem cells of three crypts appear to have a mutation in MT - COI , so that 40 % to 50 % of the cells arising from those stem cells form a white segment in the cross-cut area .