cartilage, ossification and bone disease (rest look at Callum's ESA1) Flashcards
What facilitates the ready diffusion of substances between the chondrocytes and the blood vessels surrounding the avascular cartilage?
Large ratio of GAGs (glycoaminoglycans) to type II collagen
What component of the extracellular matrix assists cartilage’s resilience to repeated application of pressure?
Large amounts of hyaluronic acid
What is the extracellular matrix of hyaline cartilage composed of?
proteoglycans, hyaluronic acid and type II collagen
Elastic cartilage has an extracellular matrix like that of hyaline cartilage but with the addition of which molecules?
Many elastic fibres and elastic lamellae
Fibrocartilage has an extracellular matrix like that of hyaline cartilage but with the addition of which molecules?
Abundant type I collagen fibres
What is the only cell type present in hyaline cartilage?
Chrondrocytes
What are isogenous groups of chondrocytes?
Chrondrocytes groups that have clearly originated from a recent mitotic division
How is hyaline cartilage so resilient to varying pressure loads?
The cartilage extracellular matrix is highly hydrated and transient moventent of water within the matrix can occur
What is the ‘territorial matrix’ and ‘interterritorial matrix’ of cartilage?
The matrix surrounding a chondrocyte or isogenous group which stains darker (with H&E). ‘Interritorial matrix’ is matrix between groups/single chondrocytes that stains lighter
What is the shrinkage artefact that is seen in histiological slides of cartilage?
Lacunae - artifical space around chondrocytes
The hyaline cartilage that forms the epithyseal growth plates and articulating surfaces of bones, is lacking what compared to the hyaline cartilage elsewhere?
Perichondrium
Where is elastic cartilage found?
External ear (pinna)
External acoustic meatus (ear canal)
Epiglottis
Eustachian tube (tube between middle ear and nasopharynx)
Fibrocartilage is different from elastic cartilage and hyaline cartilage, in that it has two not one type of cell present. Name the cells
Chrondrocytes
Fibroblasts
Fibrocartilage is like a combination of which connective tissues?
Dense regular connective tissue
Hyaline cartilage
What are some important histiological features of fibrocartilage?
Cells are often seen distributed in rows or isogenous groups
NO surrounding perichondrium
Chondrocytes not as abundant as in other types of cartilage
Where is fibrocartilage found?
Intervertebral discs
Articular disks of sternoclavicular and temporomandibular joints
Menisci of the knee joint
Pubic symphysis
At some entheses (tendon and bone attachments)
Next to the endosteum and periosteum what structures can be seen in cortical/compact bone that run paralell to the long axis of the bone?
Endosteum - Inner circumferential lamellae
Periosteum - Outer circumferential lamellae
What do Haversian canals and Volkmann’s canals carry?
Blood vessels, lymph vessels and nerves
How can you differentiate between a Haverisian and Volkmann canal?
Haversian have concentric lamellae surrounding them, Volkmann canals don’t
How are osteocytes arranged in immature bone vs mature bone?
Fairly random vs in concentric lamellae of osteons
In mature bone which direction do the reabsorption canals run?
Parallel with the osteon’s long axis
What is notable about the appearence of osteons as they travel longitudinally (in the same plane as the bone)?
They can branch into multiple osteons
How can bone be sectioned?
- Decalcified - otherwise blunts blade
2. Ground down
Where are osteocytes found in an osteon?
Entombed in lacunae between lamellae
How do osteocytes receive nutrients and get rid of waste?
They have slender cytoplasmic processes which reach out to adjacent osteocyte via canaliculi. These processes connect via gap junctions such that nutrients can be passed between them. Canaliculi are believed to connect with the central Haversian canal
What is the difference in histiological structure between cancellous and cortical bone?
Cancellous is similar to cortical (has osteocytes lying between lamellae) but has no Haversian or Volkmann’s canals.
What is the structure of cancellous trabeculae?
Each trabeculum - numerous osteocytes embedded within irregular lamellae
Osteoblast and osteoclasts on their surface act to remodel them
What lies between the trabeculae of cancellous (spongy) bone?
Adipose and haemopoietic cells
Which mineral makes up 65% of bone?
calcium hydroxyapatite crystals
Which type of collagen makes up 23% of bone?
Type 1
What is thought to confer some of the flexibility of bone?
Lamellae are thought to be able to slip, relative to each other, before excessive load causes fracture
