where "ΣQ-" is the number of the nuclei coming into focus during the scanning of “h” (the height of the disector). "ΣP" is the total number of counting frames in all fields, "a/f" is the frame area, “t” is the mean section thickness measured in every sampled field using the microcator (20 µm on average), and “BA” is the block advance of the microtome (Rubinow and Juraska, 2009[24]).