T11 Histology of Cartilage & Bone

osteoarthritic knee characteristic

cartilage tear

joint soft tissue components

cartilage, ligament, synovium

synovium function

secrete fluid that lubricate joint

cartilage types

fibrocartilage, hyaline, elastic

cartilage characteristic

firm and resilient connective tissue

cartilage composition

chondroblast, chondrocyte, extracellular matrix, type 2 collagen, ground substance

cartilage vascular/avascular

avascular

cartilage function

support soft tissue, formation and growth of long bone, durability of articular joints

chondroblast - what, location, function

progenitor of chondrocyte; border between perichondrium and matrix; produce type 2 collagen and ECM

perichondrium

CT lining cartilage mass

chondrocyte - what, location, function

mature cartilage cell; inside lacuna; produce type 2 collagen and ECM

what surrounds chondrocytes

territorial matrix

chondrogenesis types

appositional (from perichondrium), interstitial (from within cartilage)

appositional growth

chondroblast divide into chondrocyte and secrete new matrix to add cartilage beneath surface of perichondrium

perichondrium layer is site of what

chondrogenesis

what gene controls perichondrium differentiation

Sox9

interstitial growth - when, where

early hyaline cartilage formation, endochondral ossification, when still have mesenchyme; inside cartilage mass or articular cartilage or epiphyseal plate of long bone

articular cartilage lacks

perichondrium

interstitial growth process

mesenchyme differentiate into chondroblast > secrete ECM to form lacunae and become chondrocytes > divide to form isogenic groups > form own lacunae and spread apart

hyaline cartilage - components, location

type 2 collagen, GAGs, proteoglycan; articular surface, epiphyseal plate, respiratory

elastic cartilage - components, location

type 2 collagen, elastic fiber; ear pinna, epiglottis, eustachian tube

fibrocartilage - components, location

type 1 and 2 collagen, dense regular CT; IV disc, TMJ joint, pubic symphysis, insertion of tendon and ligament

hyaline cartilage characteristic

hydrated, allow matrix to respond to pressure loads (resilient)

what is a and what morphologic characteristic says so

chondroblast; no lacuna

what is b

isogenous chondrocyte

what is c

perichondrium

hyaline cartilage calcification or no

calcification

elastic cartilage calcification or no

no

what cartilage

hyaline cartilage

what cartilage

hyaline cartilage

what cartilage

elastic cartilage

what type of cartilage doesn’t have perichondrium

fibrocartilage

morphology of fibrocartilage

row-like chondrocyte

what cartilage

fibrocartilage

cartilage repair after injury

limited capability due to avascularity (stops but can’t reverse injury)

hyaline cartilage calcification occurs when

endochondral ossification, aging

bone components

cell + matrix + periosteum, endosteum

bone functions

support; protect; reservoir of calcium, phosphate; lever system

bone types

lamellar, woven

lamellar bone

osteon, haversian system, most common, compact and cancellous

osteon/haversian system

concentric lamellae around canal containing blood vessels, nerves, loose CT

cement line

collagen-rich outer border of osteon

what type of bone is depicted and what is inside the circle

lamellar bone; osteon

what is a

osteocyte

what is b

haversian canal

what cell has extended cytoplasmic processes and what are the processes called

osteocyte; canaliculi

what is the function of the central canal in lamellar bones

communicate with marrow cavity through transverse perforating or volkmann canals

what is circled in red

haversian canal

what is outlined in white

volkmann canal

woven bone characteristic

newly formed, non-lamellar, random type 1 collagens, temporary

woven bone present when

embryonic development, fracture repair

what bone is depicted on the left

lamellar bone

what bone is depicted on the right

woven bone

compact (cortical) bone - percentage, characteristics

majority; haversian system, concentric lamella, osteocyte in lacuna

cancellous (trabecular, spongy) bone - percentage, characteristics

minority, concentric lamella but not osteon

what type of bone

cancellous

endosteum of cancellous bone contains

osteoblast and osteoclast

parts of long bone

epiphysis, diaphysis, epiphyseal plate

epiphysis

expanding end, spongy bone with thin layer of compact

diaphysis

main shaft, compact bone with central marrow

epiphyseal plate

hyaline cartilage part, not fused when young

red bone marrow

children, red blood cells, hemopoietic

yellow bone marrow

older, adipocyte cells, found in diaphyseal of long bones

osteoblast - function; location

synthesize and secrete organic components (type 1 collagen, proteoglycan, glycoprotein); outermost surface of bone matrix

osteocyte - location, morphology

in lacuna; cytoplasmic processes (canaliculi)

osteoclast - derivation, morphology, function

monocyte; multinucleated; bone resorption and remodeling

what is a

osteoblast

what is b

osteoclast

what is c

osteoid (new matrix)

what is d

osteocyte

osteoblasts secrete

osteoid containing type 1 collagen, proteoglycan, glycoprotein (osteonectin)

formation of mineralized bone process

osteoblast release matrix vesicles and fiber > mineralization around vesicles > matrix compact to become mineralized bone

osteocyte

mature bone cell enclosed by matrix with dendritic processes for communication

osteocyte function

calcium homeostasis, detect stress for bone remodeling

what connections are formed between dendritic processes of osteocytes

gap junctions

hawship’s lacuna (resorption bay)

bone resorption area

regions of osteoclast during bone resorption

ruffled border, clear/sealing zone (adhesion molecules), basolateral (exocytosis or digested material)

acidified vesicles role in bone resorption

make area near ruffled border acidic to destroy bone

bone matrix composition

calcium hydroxyapatite, type 1 collagen, osteonectin, osteocalcin

perforating or sharpey fiber

bind periosteum to bone

inner periosteum contains

osteoblasts, osteoprogenitor

periosteum function

nourish osseous tissue, provide supply of osteoblast

endosteum

cover small trabeculae of bony matrix

osteogenesis types

intramembranous ossification, endochondrol ossification (intracartilaginous)

intramembranous ossification process

ossification center forms in condensed membrane > osteoid is secreted > woven bone and periosteum form > compact bone forms

endochondral ossification

within hyaline cartilage, for long bone development

endochondral ossification process

hyaline cartilage model > blood vessel penetrate for primary ossification in diaphysis > secondary ossification in epiphyses > bone replace cartilage

what regions of cartilage remain after bone development

articular cartilage, epiphyseal plate

ossification: resting zone

normal chondrocytes

ossification: proliferating zone

cell division (stacked cells)

ossification: maturation and hypertrophic cartilage zone

enlargement

ossification: calcified cartilage zone

chondrocyte replaced by calcium, apoptosis, no nuclei

ossification: ossification zone

cartilage removal and bone deposit

what is a

resting zone

what is b

proliferating zone

what is c

maturation and hypertrophic cartilage zone

what is d

calcification zone

what is e

ossification zone

what is the direction of bone growth

towards the center of the diaphyses

bone remodeling purposes

bone plasticity, cranial bone growth, stress adaptation