Haversian- and Volkmann's canals in bone (200X)

As mentioned, the darker areas in the section are either Haversian- or Volkmann's canals. The small dark spots are osteocytes. Encircling the Haversian canal you can see bony tissue arranged in circular layers. This is called an osteon. Some osteons may not be mineralized to the same extent as the rest of the tissue. That's why some tend to look darker than other osteons in this section.