A honeycomb structure includes multiple honeycomb segments joined by means of a bonding material. This population is further divided into specific myeloid progenitor subsets, including a common myeloid progenitor cells, megakaryocyteerythroid progenitor cells and granulocytemonocyte lineage progenitor. A voltage dividing circuit is connected with the positive output terminal, and has a control terminal outputting a voltage. The brightness correction may be performed on the image using a histogram of the image with an overlaid reference mark.