Types of bone

• cortical

  • Haversian systems

• trabecular

  • lamellae are mature bone; immature bone is not seen

  • fatty marrow between the trabeculae

  • osteoblasts are inactive, so we call them osteocytes

Histology

• cement lines found around each Haversian canal

• abnormal trabecular bone: a huge number of lacunae with osteocytes in them. when there is high turnover of bone, you will see a lot of osteocytes. this is actually from a patient with osteogenesis imperfecta

• active osteoblasts on the surface of bone

• pink stuff is unmineralized osteoid; blue stuff is mineralized bone

• stain bone mineral with the Von Kossa stain. this stains Ca as black, so we know that this is a fully-mineralized bone

• jagged, sawtooth appearance on the surface of the trabeculae, on the other hand, reflects resorptive bone with osteoclasts presumably doing their job

• fibrous tissue is periosteum; cortical bone is below. here periosteum is trying to manufacture new bone between itself and cortical bone

• safranin-O stain: surface of the cartilage is blue. matrix between the cartilage cells is red

• dark color indicates a lot of new bone is being formed in a very irregular fashion. this is Paget’s disease

Category: Pathology Notes