Figure 3
Section of biopsy of normal human colon stained brown with antibody to proliferating antigen Ki-67, and counterstained blue with hematoxylin. Left, example of several adjacent crypts in the tissue. Right, enlargement of a single crypt showing brown stained proliferating cells, blue stained quiescent stem cells at the bottom of the crypt, and blue stained differentiated cells in the top two-thirds of the crypt.