Bone Histology

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Bone-femur-c.jpg

Contents

Introduction

Endochondral bone.jpg
Our adult skeleton forms from a larger number of developmental elements that are replaced and fuse. In development there are 2 separate signaling pathways for pattern formation and the formation of bone itself. Furthermore bone formation can be divided into 2 specific forms that occur in anatomically different regions. This practical class will describe the development and structure of bone and finish with a study of abnormalities associated with bone.

The image shown to the left shows a histological section through the developing lower limb at the level of a developing joint (knee), surrounding the developing bone are skeletal muscles and connective tissue of the limb.

Note: This current page contains both additional information and images to the practical class set. These are provided for educational information and study purposes only. For more development background see the Science Lecture - Musculoskeletal Development and notes on Bone Development.

AEsmall.jpg
Page also provides further histology background information for Medicine phase 1 Ageing and Endings Practical Virtual Slides.
Musculoskeletal Links: Introduction | Mesoderm | Somitogenesis | Limb | Cartilage | Bone | Bone Timeline | Axial Skeleton | Skull | Joint | Muscle | Tendon | Diaphragm | Lecture - Musculoskeletal Development | Abnormalities | Limb Abnormalities | Cartilage Histology | Bone Histology | Skeletal Muscle Histology | Category:Musculoskeletal


Objectives

  • Understand the general microanatomy of bone
  • Understand bone cell types (location, structure, function)
  • Understand the histology of compact and spongy bone
  • Understand the 2 forms of developmental bone formation


Skeleton dance.gif

Textbook

Histology and Cell Biology: An Introduction to Pathology, A.L. Kierszenbaum, 2002 - Connective Tissue, Chapter 4 pp118-129; Osteogenesis, Chapter 5 pp131-145

Slides

UNSW Virtual Slidebox Virtual Slidebox Phase 1

Virtual Slidebox of Histology Decalcified rib, bone marrow | Developing bone | Paget's disease of bone

Bone Structure

Bone-structure.jpg


Terminology

  • Diaphysis - shaft
  • Epiphysis - expanded ends
  • Metaphysis - connecting region (between diaphysis and epiphysial line)
  • Medullary Cavity - (marrow) cavity within the bone.

More? Terms

Compact bone

  • (dense) no spaces or hollows in the bone matrix visible to the eye.
  • forms the thick-walled tube of the shaft (or diaphysis) of long bones, which surrounds the marrow cavity (or medullary cavity). A thin layer of compact bone also covers the epiphyses of long bones.

Trabecular bone

  • (cancellous or spongy bone) consists of delicate bars (spicules) and sheets of bone, trabeculae
  • branch and intersect to form a sponge-like network
  • ends of long bones (or epiphyses) consist mainly of trabecular bone.

Periosteum

Connective tissue covering the surface of bone (except articular surfaces).

Periosteum.jpg

Endosteum

Connective tissue lining inner surface of bone.


Bone Growth

  • Appositional growth occurs at either the periosteum (outer surface), or the endosteum (inner surface).
  • Osteoblasts secrete osteoid, a pre-bone material composed mainly of type I collagen that becomes mineralized.
  • Early bone matrix deposited in development and during repair is woven rather than lamellar in appearance and structure.
  • In development, there are 2 distinct types of bone formation (intramembranous and endochondral)

Bone Cells

Osteoblasts

Mouse osteoblast 01.jpg

  • derive from osteogenic stem cells the osteoprogenitor cells that differentiate to form pre-osteoblast then osteoblasts maturing to an osteocyte
  • osteoprogenitor cells - "resting cell" line the inner and outer surfaces of bone

Osteocytes

  • mature bone-forming cells embedded in lacunae within the bone matrix
  • osteoblasts and osteocytes - secrete organic matrix of bone (osteoid), converted into osteocytes when become embedded in matrix (which calcifies soon after deposition)

Osteoclasts

Mouse osteoclast 01.jpg Osteoclast.jpg Bone remodeling cycle.jpg

  • bone-resorbing multinucleated macrophage-like cells
  • origin- fusion of monocytes or macrophages, Blood macrophage precursor, Attach to bone matrix
  • seal a small segment of extracellular space (between plasma membrane and bone surface), HCl and lysosomes secreted into this space by osteoclasts dissolves calcium phosphate crystals (give bone rigidity and strength)
    • Resorptive bay - (Howship's lacuna) shallow bay lying directly under an osteoclast.
  • do not mistake for megakaryocytes, found in bone marrow not associated with bone matrix.
    • megakaryocytes are also multi-niucleated and form platelets

Bone Marrow

Hematopoietic and stromal cell differentiation
  • red marrow - mainly haematopoietic (myeloid) tissue, newborn has all red marrow
  • yellow marrow - mainly fat cells, found in diaphysis region of long bones
  • stromal cells - all other support cells not involved in haematopoiesis

Chondroblasts and Chondrocytes

  • immature and mature cartilage forming cells located at articular cartilage regions.
  • Interstitial growth - occurs mainly in immature cartilage. Chondroblasts in existing cartilage divide and form small groups of cells (isogenous groups) which produce matrix to become separated from each other by a thin partition of matrix.
  • Appositional growth - occurs also in mature cartilage. Mesenchymal cells surrounding the cartilage in the deep part of the perichondrium (or the chondrogenic layer) differentiate into chondroblasts.


Links: Cartilage Histology

Bone Matrix

The bone matrix has 2 major components.

  • Organic portion composed of mainly collagen Type 1 (about 95%) and amorphous ground substance.
  • Inorganic portion (50% dry weight of the matrix) composed of hydroxyapatite crystals, calcium, phosphorus, bicarbonate, nitrate, Mg, K, Na.
    • storage calcium and phosphate
    • regulate blood calcium levels

Haversian Systems

Bone structure cartoon
  • also called osteons
  • Volkmann's canals - interconnect Haversian systems

Lamellae

  • concentric - surrounding each Haversian System
  • interstitial - bony plates that fill in between the haversian systems.
  • circumferential - layers of bone that underlie the periosteum and endosteum

Cells

  • osteocytes extending cytoplasmic processes into canaliculi
  • Additional Histology images: low | medium | high

Endochondral ossification

Endochondral bone.jpg

Endochondral ossification slides: Developing bone | Bone, Developing (LS, Femur) Cat H&E

Blue Histology - endochondral | Dev Biology - endochondral ossification | endochondral ossification animation

Endochondral ossification.jpg Endochondral ossification 2.jpg

Ossification endochondral 1c.jpg Articular cartilage.jpg


Bone Histology: Cartilage Histology | Histology Stains | Histology | Cartilage Development | Bone Development
Compact bone Compact canals | Compact lamellae | compact bone - low unstained | compact bone - high unstained | compact - low | compact - low | compact - med | compact - high |
Trabecular bone trabecular | lamellar | trabecular - overview HE | trabecular - low HE | trabecular - med HE
Endochondral ossification primary ossification | endochondral ossification
Intramembranous ossification intramembranous - VG low | intramembranous - VG high | intramembranous - HE low | intramembranous - HE high

Intramembranous Ossification

Intramembranous ossification slides: Head (Neonatal) Rat H& Van Gieson

Blue histology - intramembranous

Ossification centre.jpg Intramembranous ossification centre.jpg


Bone Histology: Cartilage Histology | Histology Stains | Histology | Cartilage Development | Bone Development
Compact bone Compact canals | Compact lamellae | compact bone - low unstained | compact bone - high unstained | compact - low | compact - low | compact - med | compact - high |
Trabecular bone trabecular | lamellar | trabecular - overview HE | trabecular - low HE | trabecular - med HE
Endochondral ossification primary ossification | endochondral ossification
Intramembranous ossification intramembranous - VG low | intramembranous - VG high | intramembranous - HE low | intramembranous - HE high

Human Fetal Head (12 week)

Fetal head medial.jpg Fetal head lateral.jpg

Meckel.jpg

Fetal head section.jpg

Histology Stains

Alizarin Red

  • an anthraquinone derivative used to identify calcium in tissue sections
  • calcium forms an Alizarin Red S-calcium complex in a chelation process and the end product is also birefringent.
  • reaction can also identify magnesium, manganese, barium, strontium, and iron may interfere
    • these elements usually in too low concentration to interfere with the staining

H&E

  • acronym for hematoxylin and eosin stain
  • hematoxylin - basic dye which colors basophilic structures with blue-purple hue (nucleus, DNA, RNA)
  • eosin Y - acidic alcohol-based which colors eosinophilic structures bright pink (cytoplasm, extracellular matrix, protein)

H&Van Gieson

  • Van Gieson's Stain is a mixture of picric acid and acid fuchsin used for differential staining of collagen and other connective tissue.
    • Nuclei - stains brownish black to black
    • Collagen (fibrous connective tissue) - stains pink or deep red
    • Muscle, Cytoplasm, RBC and Fibrin - stains yellow


Links: Histology Stains

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name.

Other Textbooks

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Terms

Axial skeleton
Appendicular skeleton
  • canaliculus - (plural, canaliculi) small channel in the bone matrix in which an osteocyte process lies and communicates with other osteocytes and the Haversian canal.
  • haematopoiesis (Greek, haima = "blood"; poiesis = "to make") the process of blood cell formation.
  • Haversian canal - the central canal of an osteon (Haversian system) in compact bone, within which blood vessels and nerves travel throughout the bone.
  • Haversian system - (osteon) the historic name for the functional unit of compact bone. Consists of a central canal (Haversian canal) surrounded by lamellar bone matrix within which osteocytes reside.
  • Howship's lacuna - (resorptive bay) the historic name for the shallow bay or cavity lying directly under an osteoclast. This is the site of bone matrix resorption.
  • lacuna - (Latin, lacuna = “ditch, gap” diminutive form of lacus = “lake”) lacunae is the plural, cavity in bone or cartilage for cell.
  • lamellar bone - the highly organized strong bone matrix deposited in concentric sheets with a low proportion of osteocytes. Many collagen fibers parallel to each other in the same layer.
  • osteon - (Haversian system) the functional unit of compact bone. Consists of a central canal (Haversian canal) surrounded by lamellar bone matrix within which osteocytes reside.
  • resorptive bay - (Howship's lacuna) the shallow bay or cavity lying directly under an osteoclast. This is the site of bone matrix resorption.
  • suture - in the skull a form of articulation where the contiguous margins of the bones are united by a thin layer of fibrous tissue.
  • woven bone - the first deposited weaker bone matrix with many osteocytes and a matrix disorganized structure. Replaced by lamellar bone. Seen in developing, healing and bone disease.


Glossary Links

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Cite this page: Hill, M.A. (2014) Embryology Bone Histology. Retrieved April 23, 2014, from http://embryology.med.unsw.edu.au/embryology/index.php?title=Bone_Histology

What Links Here?
Dr Mark Hill 2014, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
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