1. Histology + Embryology of Bone Flashcards
Cartilage
Chondrocytes + collagen fibres
Types of Cartilage
1) Hyaline
2) Elastic
3) Fibrocartilage
Hyaline Cartilage
Blue/white translucent appearance
Fibrocartilage
small islands of chondrocytes + ground substance
Elastic Cartilage
Large number of elastic fibres
Yellow appearance
Percentage of cells in hyaline Cartilage
3-5%
Percentage of multiadhesive glycoproteins in hyaline Cartilage
5%
Percentage of proteoglycans in hyaline Cartilage
9%
Percentage of collagen in hyaline Cartilage
15%
Percentage of intercellular water in hyaline Cartilage
60-80%
How is Cartilage formed?
differentiated multipotent stem cells → chondroid precursor cells → chondroblasts
these secrete type II collagen and GAG
Endochondrial ossification
Bone formed in space of destroyed Cartilage
Membranous Ossification
Bone formed from membrane
Intra-membranous ossification
Misses out Cartilage step, goes directly from mesenchyme
Takes place in formation of flat bones of skull, clavicle + bones of face
Osteoblasts
- Secrete osteoid (type 1 collagen + GAG)
- osteoid forms hydroxylapatite (crystalline structure)
- leads to appositional growth (fatter rather than longer bones)
- not multinucleated
Osteoclasts
-breakdown bone matrix
Osteocytes
An osteoblast in the bony matrix
Two types of bone
1) Compact
2) Spongy
Compact bone
- embedded osteocytes
- layers of cylinders => Haversian canals => Haversian Systems
Spongy bone
- network of trabeculae
- spaces filled with yellow + red bone marrow
Periosteum
- outer surface of bone
- osteogenic = can make new bone cells
- adheres to bone underneath via Sharpley’s fibres
