ossification and cartilage development

Question 1

what kind of ossification involves formation of a cartilaginous precursor

Answer 1

endochondral

Question 2

type of ossification involved in formation of bones of skull

Answer 2

intramembranous

Question 3

whihc ossification results in formation of woven bone that is later replaced by lamellar bone

Answer 3

endochondral

Question 4

what ossification does growth occur by differentiation of mesenchymal cells into osteoblasts

Answer 4

intramembranous

Question 5

why type of ossificiation involved in growth in length of long bones

Answer 5

endochondral

Question 6

what kind of ossification is involved in the growth in width in long bones

Answer 6

intramembranous

Question 7

where does enochondral ossification occur

Answer 7

• physes or growth plates: increase in length of long bones
• epiphsyses: increase in size and linked with joint cartilage growth
• cuboidal bones of the carpus and tarsus
• repair of fractures: this is the same as bone growth, hence the reason why bone does not scar

Question 8

what is the order of events in which endochondral ossification occurs

Answer 8

1. chondrocytes proliferate and secrete cartilage extracellular matrix
2. chonrocytes form into columns and undergo hypertrophy
3. cartilage matrix calcifies
4. cartilage matrix is invaded by blood vessels
5. osteoclasts, bone marrow cells and osteoblasts are delivered to growth cartilage
6. osteoid is depositied on spicules of calcified cartilage matrix
7. primary spongiosum is replaced by woven bone
8. secondary spongiosum is replaced by lamellar bone

Question 9

true or false: some physes close before birth

Answer 9

true

Question 10

T/F: An apophysis is a bony outgrowth (a tuberosity) that develops under tension and that has its own centre of ossification

Answer 10

true

Question 11

T/F: it is important to refer to physeal closure times because an open or closing physis can mimic a fracture on radiographs

Answer 11

true

Question 12

T/F: in the horse, the distal radial physis closes before the distal physis of the third metacarpal bone

Answer 12

False:
Distal radius closes at 20-24 months
Distal MCIII closes at 6 months

Question 13

T/F: premature foals are at risk of angular limb deformity because the cuboidal bones of the carpus and tarsus may be incompletely ossified at the time of birth

Answer 13

true

Question 14

true or false: osteochondrosis is a developmental condition that primarily affects bone

Answer 14

False: OCD is a developmental condition that originates as a defect during endochondral ossification. ischaemic chondrosis associated with failure of cartilage canal vessels at the chondro osseus junction

Question 15

T/F: once an osteochondrosis lesion has formed in the AECC, the animal is highly likely to show clinical signs of joint disease at a later date

Answer 15

False: in the majority of young horses OCD lesions heal. Since OC start with just a cartilage defect, the cartilage can be converted into bone as the animal grows, thus getting rid of the lesion. if the defect is severe, then synovial fluid can be access the subchondral bone plate at which point DJD is far more likely