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  • 2013 Pearson Education, Inc.Bone DevelopmentOssification (osteogenesis)Process of bone tissue formationFormation of bony skeletonBegins in 2nd month of developmentPostnatal bone growthUntil early adulthoodBone remodeling and repairLifelong

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Two Types of OssificationEndochondral ossificationBone forms by replacing hyaline cartilageBones called cartilage (endochondral) bonesForms most of skeletonIntramembranous ossificationBone develops from fibrous membraneBones called membrane bonesForms flat bones, e.g. clavicles and cranial bones

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Endochondral OssificationForms most all bones inferior to base of skullExcept claviclesBegins late in 2nd month of developmentUses hyaline cartilage models Requires breakdown of hyaline cartilage prior to ossification

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Endochondral OssificationBegins at primary ossification center in center of shaftBlood vessel infiltration of perichondrium converts it to periosteum underlying cells change to osteoblastsBone collar forms around diaphysis of cartilage modelCentral cartilage in diaphysis calcifies, then develops cavitiesPeriosteal bud invades cavities formation of spongy boneDiaphysis elongates & medullary cavity formsEpiphyses ossify

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Week 9Month 3BirthChildhood toadolescenceHyalinecartilageBone collarPrimaryossificationcenterArea ofdeterioratingcartilage matrixSpongyboneformationBloodvessel ofperiostealbud Epiphysealblood vesselSecondaryossificationcenterArticularcartilageSpongyboneEpiphysealplatecartilageMedullarycavity Bone collarforms around thediaphysis of thehyaline cartilagemodel. Cartilage in thecenter of thediaphysis calcifiesand then developscavities. The periostealbud invades theinternal cavitiesand spongy boneforms. The diaphysiselongates and amedullary cavityforms. Secondaryossificationcenters appear inthe epiphyses. The epiphysesossify. Whencompleted, hyalinecartilage remainsonly in theepiphyseal platesand articularcartilages.12345Slide 1

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Week 9Hyalinecartilage Bone collar forms around thediaphysis of the hyaline cartilage model.1Bone collarPrimaryossificationcenterSlide 2

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Area of deterioratingcartilage matrix Cartilage in the center of the diaphysis calcifies and then develops cavities.2Slide 3

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Month 3SpongyboneformationBloodvessel ofperiostealbud The periosteal bud invades the internal cavities and spongy bone forms.3Slide 4

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Epiphysealblood vesselSecondaryossificationcenterMedullarycavityBirth The diaphysis elongates and a medullary cavity forms. Secondary ossification centers appear in the epiphyses.4Slide 5

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Childhood toadolescenceArticularcartilageSpongyboneEpiphysealplatecartilage The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages.5Slide 6

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.8 Endochondral ossification in a long bone.Week 9Month 3BirthHyalinecartilageBone collarPrimaryossificationcenterArea ofdeterioratingcartilage matrixSpongyboneformationBloodvessel ofperiostealbud Epiphysealblood vesselSecondaryossificationcenterMedullarycavity Bone collarforms around thediaphysis of thehyaline cartilagemodel. Cartilage in thecenter of thediaphysis calcifiesand then developscavities. The periostealbud invades theinternal cavitiesand spongy boneforms. The diaphysiselongates and amedullary cavityforms. Secondaryossificationcenters appear inthe epiphyses. The epiphysesossify. Whencompleted, hyalinecartilage remainsonly in theepiphyseal platesand articularcartilages.12345Slide 7Childhood toadolescenceArticularcartilageSpongyboneEpiphysealplatecartilage

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Intramembranous OssificationForms frontal, parietal, occipital, temporal bones, and claviclesBegins within fibrous connective tissue membranes formed by mesenchymal cellsOssification centers appearOsteoid is secretedWoven bone and periosteum formLamellar bone replaces woven bone & red marrow appears

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.Fibrous periosteumOsteoblastPlate ofcompact boneDiplo (spongy bone)cavities contain redmarrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. Spongy bone (diplo), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow.MesenchymalcellCollagen fibrilOssification centerOsteoidOsteoblast 1 Ossification centers appear in the fibrous connective tissue membrane. Selected centrally located mesenchymal cellscluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae ofspongy bone.Slide 1OsteoblastOsteoidOsteocyteNewly calcifiedbone matrix 2 Osteoid is secreted within the fibrous membrane and calcifies. Osteoblasts begin to secrete osteoid, which calcifies in a few days. Trapped osteoblasts become osteocytes.Mesenchymecondensingto form the periosteumTrabeculae ofwoven boneBlood vessel 3 Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae called woven bone. Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum.

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.Mesenchymal cellCollagen fibrilOssification centerOsteoidOsteoblast 1 Ossification centers appear in the fibrous connectivetissue membrane. Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae of spongy bone.Slide 2

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.OsteoblastOsteoidOsteocyteNewly calcifiedbone matrix 2 Osteoid is secreted within the fibrous membrane andcalcifies. Osteoblasts begin to secrete osteoid, which calcifies in a few days. Trapped osteoblasts become osteocytes.Slide 3

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.Trabeculae ofwoven boneBlood vessel 3 Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae called woven bone. Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum.Mesenchymecondensingto form the periosteumSlide 4

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.Fibrous periosteumOsteoblastPlate ofcompact boneDiplo (spongy bone)cavities contain redmarrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. Spongy bone (diplo), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow.Slide 5

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Figure 6.9 Intramembranous ossification.Fibrous periosteumOsteoblastPlate ofcompact boneDiplo (spongy bone)cavities contain redmarrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. Spongy bone (diplo), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow.MesenchymalcellCollagen fibrilOssification centerOsteoidOsteoblast 1 Ossification centers appear in the fibrous connective tissue membrane. Selected centrally located mesenchymal cellscluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae ofspongy bone.Slide 6OsteoblastOsteoidOsteocyteNewly calcifiedbone matrix 2 Osteoid is secreted within the fibrous membrane and calcifies. Osteoblasts begin to secrete osteoid, which calcifies in a few days. Trapped osteoblasts become osteocytes.Mesenchymecondensingto form the periosteumTrabeculae ofwoven boneBlood vessel 3 Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae called woven bone. Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum.

    2013 Pearson Education, Inc.

  • 2013 Pearson Education, Inc.Postnatal Bone GrowthInterstitial (longitudinal) growth

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