Fig. 3. Immunohistochemical staining of human intestinal mucosa. The staining for frataxin was performed using anti-frataxin antibody. Along the crypt-villus axis the stem cells committed to become mature enterocytes migrate and differentiate. Proliferating undifferentiated cells are located towards the base of the crypt compartment, while differentiated cells are located at the tips of the villus. Frataxin signal corresponding to the brown staining become clearly evident in the upper half of the villus (arrowheads indicate). Magnification used is 40x.