Osteoblasts are normal cells that are involved in bone formation. They are sometimes present in aspirates of bone marrow or touch preparations of trephine biopsies from bone marrow. They are large cells with round or oval nuclei, one or more nuclei and abundant blue-gray cytoplasm. A prominent clear zone or hof of Golgi is often present in the cytoplasm. Osteoblasts may be difficult to differentiate from plasma cells, but plasma cells are usually smaller, the nuclear chromatin pattern more condensed, and the cytoplasm a deeper blue.
Osteoclasts are very large cells with multiple, seperate round to oval, uniformly sized nuclei.
The nuclear chromatin is condensed with one or more nucleoli. The cytoplasm is abundant, blue to purple in color and contains reddish-purple granules. Osteoclasts are normal cells that are involved in bone resorption. Morphologically they may closely resemble megakaryocytes, but megakaryoctes possess nuclei with multiple overlapping lobes and nucleoli are usually absent. Megakaryocyte cytoplasm is granular but the granules are usually smaller and more uniform in appearance than in osteoclasts.