Histology of Bone and Cartilage Flashcards
What are isogenous groups?
daughter dividing cells in lacunae. These groups are able to form due to the fluidity of ECM
Osteocytes in the lacunae secrete this substance around the ground substance…
territorial matrix
What’s ECM made of?
collagen fibrils, proteoglycans, glycoproteins, and glycosaminoglycans (HA, chondritan sulfate, keratan sulfate, dermatan, heparin sulfate)
What’s function with aggrecan?
aggrecan+hyaluron make up proteoglycan aggregates which aggregates absorb the H2O. When cartilage relaxes, negative proteoglycan aggregates attract the water
Describe the features of perichondrium.
vascular supply of the cartilage, between the cartilage and supporting tissue. Outer layer - dense irregular CT that contains fibroblasts and inner layer chondroblasts
Histogenesis
mesenchyme >condense>divide>separate(chondrocytes)> isogenous groups (interstitial growth- mitotic division of preexisting chondrocytes) > growth in width (appositional growth) differentiation
Collagen type II, glassy appearance, has ground substance made of glycosaminoglycans, proteoglycans, glycoproteins
Hyaline Cartilage
Where can you find hyaline cartilage?
Fetal skeleton, sternal ribs, trachea, larynx, nose, epiphyseal plate
Where can you find elastic cartilage?
external ear, external auditory meatus, auditory tubes, epiglottis
Collagen type 1, no perichondrium
fibrocartilage which makes up intervertebral discs, pubic symphysis, and insertions of tendons
What are 6 differences between Bone and cartilage?
bony has hard salts in matrix, nutrients can’t diffuse through, there’s vasculature, lacunae linked by canaliculi, fibrils organized into lamellae, and appositional growth
Secretes matrix in woven or organized pattern, type 1 collagen, important for mineralization
Osteoblast
Reside in lacunae, with canaliculi, orchestrate bone remodeling
Osteocyte
Hematopoietic origin, secretes specialized enzymes that break bone matrix
Osteoclasts
What are extracellular matrix inorganic components?
Calcium, phosphorus, hydroxyapatite crystals
What are organic compounds of bone extracellular matrix?
type 1 collagen, glycosaminoglycans, proteoglycans, glycoproteins
Primary vs Secondary Bone
Primary is woven bone that has random deposition of collagen, low mineral content
Secondary is lamellar collagen fiber parallel arrangement with Haversian (osteon vessel) system
Links adjacent Haversian canals
Volkman’s canals
How do we get from woven bone to mature Haversian bone?
ossification>woven bone>remodeling>lamellar> Haversian system
What happens to our body every 10 years?
our skeleton is regenerated, so new Haversian systems and lamella
Intramembranous ossification
mesenchymal cells into osteoblasts, then direct mineralization of matrix secreted from osteoblasts
Type of craniostenosis where there’s exophtalmos (bulging eyes) and mutation in fibroblast growth factor receptor
Crouzon Syndrome
Type of craniostenosis where there’s skull and midfacial abnormalities, syndactyly, and mutation in fibroblast growth factor receptor 2
Apert Syndrome
Enchondral Ossification zones
Resting Zone, Proliferative Zone, Hypertrophic cartilage zone, Calcified cartilage (osteoblasts invade), ossification zone
increased bone mass due to abnormal osteoclasts
osteopetrosis
Brittle bone disease, abnormal collagen type 1
osteogenesis imperfecta
Steps of fracture repair
- hematoma ad cell death, 2. reabsorption by macrohphages and osteoclasts, 3. Fibrocartilage soft callus formed, 4. Hard callus of woven bone, 5. Stresses on immature bone lead to remodeled lamella bone
