The reason why collagen fibers are difficult to distinguish under LM: the fibers are extremely thin; the refractive index is similar to that of the matrix

cartilage tissue

Distribution: intervertebral disc, articular disc, pubic symphysis, tendon attachment collagen fiber bundles toughness

Distribution: auricle, external auditory canal, Eustachian region spandex elasticity

Adult organic:inorganic=3:7

Collagen fibers are arranged in parallel layers and adhere to bone salt and amorphous matrix

The fibers in the same layer of bone plates are parallel to each other, and the fibers of adjacent bone plates are perpendicular to each other.

Stem cells, periosteum of adjacent bone tissue, derived from mesenchymal cells

The surface of bone tissue, a layer with protrusions RER, GC, free ribosomes Containing calcium sulfate dense granules and matrix vesicles Produce osteoid

within or within bone plate gap junction bone lacunae, bone canaliculus Osteolysis and osteogenesis, Ca and P balance Produce osteoid

Large multinucleated cells derived from monocytes LM: striated border-like, foamy cytoplasm EM: ruffled edge, lysosome, bright area (containing microfilaments) Osteolytic microenvironment; dissolve and absorb bone matrix; increase blood calcium

The outer ring has many layers of bone plates and is neatly arranged. The inner ring bone plate has few layers and is uneven

Located between the inner and outer ring bone plates Central tube and concentrically arranged bone unit plates The bony canaliculi of a bone unit are connected, and the innermost bony canaliculi open into the central canal. There is a bonding line on the outermost surface

Irregular, without a central canal, it is the remnant of the original bone unit or the inner and outer ring bone plates that have been absorbed.

Outer layer: DCT is a dense connective tissue with thick and dense collagen fibers that penetrate the outer ring bone plate and are penetrating fibers or Sarby fibers to fix the periosteum and ligaments. Inner layer: LCT loose connective tissue, containing osteoprogenitor cells, small blood vessels and nerves

Bone marrow cavity surface, trabecular bone surface, Haversian canal inner surface, perforating canal inner surface thin layer of connective tissue Small blood vessels, single layer of osteoprogenitor cells