Lecture 16: Bone Pathology Flashcards
What is diaphonization
double staining technique, stain bone alizarian red and cartilage alcian blue
what technique was used here
diaphonization- bone red, cartilage blue
what are osteoblasts
initiate mineralization, form bone matrix and also assist osteocytes with Ca2+ homeostasis
what are osteocytes
formed when osteoblasts have been surrounded by mineralized osteoid, occupying small clear spaces called lacunae
Maintain bone Tissue
what is the most abundant cell in the bone
osteocytes
what are osteoclasts
cells derived from hematopoietic stem cells, multinucleated cells responsible for bone resorption
identify blue, black and pink arrows
Pink: bone matrix
Blue: osteocytes
Black: osteoclasts
identify 1-3 and what stain used
- Mineralized bone
- Osteoblasts
- Hematopoietic marrow
Stain: von kossa
what are the structural and functional units of cortical bone
osteons
what are osteons
cylinders of concentric layers of lamellae parallel to longitudinal axis of bone that contain vessels and nerves
what connects osteons
volkmann canal
what is intramembranous ossification and what bones
flat bones of the skull mesenchymal cells differentiate into osteoblasts that produce bone directly, in absence of preformed cartilage model
what is endochondral ossification and what bones formed
forms most bones
Cartilage is invaded by capillary vessels and undergoes minaerlization and forms primary (diaphyseal) and secondary (epiphyseal) ossification centers
describe the development of lone bone and vascularization
nutrient artery enters mineralized cartilaginous tissue in the diaphysis bringing osteoclasts and osteogenic precursors enabling endochondrial ossification in primary ossification centers
Epiphyseal arteries bring in osteoclasts and osteogenic cells to the secondary ossification centers located at end of growing long bones
Enastomoases occurs as bones continue to develop and subarticular growth cartilage is replaced by bone and growth plates close
bone grows in length by __
interstitial growth within metaphyseal growht plates (phases)
what are the 4 zones of physes
- Reserve or resting zone
- Proliferative zone
- Hypertrophic zone
- Calcifying zone
what occurs in reserve or resting zone
source of cells for proliferative zone
what occurs in proliferative zone
cells multiple, accumulate glycogen and produce matrix and become arranged in longitudinal columns
what is hypertrophic zone
chondrocytes secrete macromolecules to allow capillary invasion and initiate matrix calcification
what is calcifying zone
chondrocytes either undergo apoptosis or transform to osteoblasts initiate mineralization process
identify physes zones 1-4
- Reserve or resting
- Proliferative zone
- Hypertrophic zone
- Calcifying zone
which photo represents and adult vs puppy
Left- puppy- growth plates opened
Right- adult- growth plates closed
what is metaphysis ossification
osteoblasts and osteoclasts replace with mineralized bone tissue
identify arrows 1-2
- Primary spongiosa
- Secondary spongiosa
how does growth of epiphysis occur
endochondral ossification at articualr epiphyseal cartilage complexes
bone grows in width by __
intramembranous bone formation
the surface of bones are covered by __ which contain __ and __
peristeum, inner osteogenic layer and outer fibrous layer
what is function of inner osteogenic layer of periosteum
forms normal lamellar appositional bone on cortex of growing bones and also forms abnormal woven bone in response to injury
what is function of fibrous layer of peristeum
structural support
identify layers of periosteum
- Outer fibrous layer
- Inner osteogenic layer
normal joint- identify 1-3
- Joint space
- Articular cartilage
- Growth plate
what are type A synoviocytes
CDa1-, CD11b+, CD18+ histiocytes, antigen presenting/phagocytic
what are type B synoviocytes
fibroblasts that can produce synovial fluid
what are perivascular interstitial dendritic cells in joint
CD1a+, CD11c+, CD18+ histiocytes
what wrong and what cause
Growth plate arrest lines due to nutritional deficiencies
what wrong
Growth plate arrest lines
what wrong and what potential cause in dogs and cows
growth retardation lattice due to acquired impariemnt of osteoclastic resorption
Cows: BVDV
Dogs: canine distemper virus
what causes growth retardation lattice to occur
acquired impairment of osteoclastic respiration of bone, resulting in retention in lattice
cow tibias- which normal vs abnormal. What wrong and what cause
Left: normal
Right: growth retardation lattices due to BVDV
what wrong and what potential cause. What associated lesions would you see in bone
Left: footpad hyperkeratosis
Right: enamel hypoplasia
Cause: canine distemper virus
Bone lesions: growth retardation lattice
what is osteopetrosis
characterized by increased bone density due to failure of osteoclast resorption caused by mutation or impairment of osteoclasts
most fetuses with osteoporosis are __
stillborn
Animals who survive osteoporosis are more prone to __
fractures
what gene in red angus cattle is associated with osteoporosis
Deletion mutation of SLC4A2
what are some signs of osteoporosis
anemia, brainstem compression, brachygnathia inferior, impacted teeth
red angus: what wrong and what could have caused these
left: brachygnathia inferior
Right: impacted teeth
Cause: osteoporosis- defect in osteoclast resorption. gene point deletion: SLC4A2
what infectious agents can cause osteoporosis
BVDV, canine distemper virus, FeLV
what wrong
Osteoporosis- increase bone density, but thin cortices
Histo: pale blue- retained cartilaginous cores, osteoclasts increased in number but ineffective resorbing retained bone
what is Wolff’s law
ability of bone to change shape or size to accommodate altered mechanical use
tension causes bone __
resorption
compression causes bone __
formation
normal mechanical use leads to suppression of __activity= __
resorptive activity- maintenance of bone mass
decrease mechanical use results in
bone resorption, less mass
increased mechanical use results in
increase bone mass
which normal vs abnormal and what could’ve caused
Left: normal
Right: osteopenia due to decreased mechanical use
what wrong and what cause
osteoscleorosis of vertebrae due to increased mechanical use
Notice circled vertebrae disc is moved ventrally due to increase bone
what is woven bone
newly formed, hypercellular bone deposited in reaction to injury or normally present in immature individuals
identify what type of bone indicated by 1-2
- Lamellar bone
- Woven bone
what is a common response to injury periosteum
osteophytes- fibrocartilage capped bony outgrowths
why do osteophytes occur
response to joint injury/instability
what wrong and what cause
Osteophytes formation- joint injury/instability
t or f: hyaline cartilage has great regenerative capacity due to good blood supply
false- limited response to injury due to no blood supply
what is sterile injury caused by
trauma, joint instability or lubrication failure
what are matrix metalloproteinases in joints- what is normal vs abnormal form
enzymes capable of digesting joint matrix
Normally in inactive X form, but enzymes activated by products of degenerating or reactive chondrocytes and inflammatory cells
what is the result of loss of proteoglycans from cartilage
alters hydraulic permeability= abnormal joint lubrication—> increase susceptibility to mechanical induced injury to cartilage
joints with loss of proteoglycans grossly appear __
yellow/tan, dull, roughened
what is fibrillation
condensed and fray collagen fibers due to loss of proteoglycans
what is eburnation
smooth and shiny surface of subchondral bone after cartilage ulceration
Joint surface- what wrong
fibrillation and eburnation
humeral head- what wrong
eburnation
what are the 3 ways synovium responds to injury
- Villus hypertrophy and hyperplasia
- Hypertrophy and hyperplasia of synoviocytes
- Pannus formation
what is pannus
fibrovascular and histiocytic tissue (granulation tissue) that arises from synovial membrane and spreads as a membrane over articular cartilage. Histiocytes and collagenases from fibroblasts cause lysis and degeneration of underlying cartilage and eventually lead to ankylosis (joint fusion)
what is the pathogenesis of fibrous ankylosis
synovitis—> pannus formation—> obliteration of articular space—> ankylosis (fusion)
what wrong
P3 and P2 ankylosis (fusion)- purple between P2 and P3 bone formation.
