Preparation of Liver Tissue for the Evaluation of Mitotic Activity
AbstractHigh quality images of nuclei for mitotic counts in mouse liver tissue in which the various mitotic phases can be classified, are obtained by fixing in Lillie's neutral buffered formaldehyde solution, 8-24 hr at 4 C and then immersing 2-4 hr in Sanfelice's fixative (1% CrO 3 , 16; formalin, conc., 4; acetic acid, 1) followed by washing in tap water 12-24 hr. To count in zones of the same fixation quality, the procedure devised is as follows: Run the entire right caudoventral (triangular) lobe through the fixation and chromating process. Wash and cut off the concave surface to provide a flat face for sectioning. In the sections obtained, three zones can be distinguished. An external one unsuited for counts, a deeper zone suitable for counts, where the fixation is very good and a third or central zone where the fixation becomes gradually worse. Counts are made in microscopic fields which are selected as a row, one field width from the external surface of the organ. This fixation and orientation minimizes the interference of technical factors on the counting procedure and permits an accurate assessment of the stages of cell division to be made.