Periosteum And Endosteum

Periosteum And Endosteum

1. Endosteum

   • Membrane that lines the part of the bone marrow cavity
     • Structure
       • Made up of thin layers of flattened osteoprogenitor cells and type III collagen fibers (reticular fibers)
     • lining membrane of the bone marrow
     • Covers Haversian canal and all internal cavities of bone.
   • It is classified according to its location
     • Cortical endosteum
       • Lines the medullary canal
     • Osteon endosteum:
       • Lining the osteons
     • Trabecular endosteum:
       • Lines the trabecula near the developing part of the bone.

2. Periosteum

   • Covers the outer layer of bone except where there is union of ligaments, tendons or articulated catrilagus
     • Structure
       • Composed of two layers
         • Outer fibrous membrane
           • Dense irregular connective tissue with abundant collagen fibers
           • it's divided in
             • Surface layer
               • It is vascular (periosteal vessels)
             • Deep layer
               • composed of fibro-elastic layers
         • Inner cellular layer
           • Made up of osteoprogenitor cells
             • Adult bones
               • Osteoblasts absent, appear when necessary
             • Young bones
               • Developing osteoblasts
           • Vascular structure
             • microvessels called pericytes
               • Increase the proliferation of osteoblasts from osteoprogenitor cells (multipotent stem cells)
   • Irrigation
     • They are thin and branch to irrigate the Haversian and Volkmann canals.
   • as you age, the periosteum becomes thinner

3. Function

   • Nutrition to the bony tissue
     • Irrigation
       • The periosteal blood vessel supplies the bone wall and internal bone tissue
     • Innervation
       • Vasomotor nerve fibers control blood flow through the internal cavity
   • Bone growth
     • Endostium
       • The endosteum stimulates the internal bone resorption of the bone in order to continuously increase the diameter of the bone, this process slows down as adulthood is reached until it stops completely.
     • Periosteum
       • Has osteoprogenitor cells that are important in bone growth
   • Repair
     • The osteoprogenitor cells of the periosteum are multipotent stem cells, responsible for promoting bone development whenever necessary
   • Bone modeling and remodeling
     • The periosteum, and endosteum, play an important role in modeling and remodeling.
       • Bone remodeling
         • osteoclasts and osteoblasts are responsible for sequentially reshape and renew bone
       • Bone modeling
         • Process in which bone structure is formed during growth, development and healing
   • Calcium Homeostasis
     • Endosteum participates in the deposition of calcium in the matrix and serves as a medium for the transfer of calcium between the bone matrix and the blood
   • Bonding medium
     • The periosteum serves as a means of attachment for the muscles, tendons and ligaments to the bone
   • Limiting membrane
     • Periosteum, prevents its own expansion outside the bone tissue

4. Pathophysiology

   • Periostitis
     • Caused by infection, severe pain, pus formation, pain, may result in necrosis
     • It is generated in the deepest osteogenic layer of the periosteum due to inflammation and secretions around the vessels; causing the periosteum to separate from the bone causing its destruction.

5. Tissue Preparation

   • Ground Section of the Bone:
     • Bone histology can be observed using microscopes this technique is based on studying decalcified bone without any staining
   • Undecalcified Bone Preparation
     • Fluorochrome examination.
     • Immunohistochemical staining techniques
     • Fluoresence Microscopy
     • Tartrate-resistant acidic phosphatase (TRAP) stain

6. Histochemistry and Cytochemistry

   • Haematoxylin and Eosin
   • Von Kossa staining
   • Masson Goldner's Trichrome
   • Immunohistochemical Staining and Fluorescence

Images and files in the map