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.
- New 2011 page - Bone Histology
- 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
Practical Audio 2009
Files below are Quicktime audio files recorded Wednesday 12 - 2 PM class (Podcast MP3 versions to follow).
- MH - Please note "perichondrium" instead of "periosteum" error somewhere in the above audio. Open in a separate tab to play the audio in the background.
Histology and Cell Biology: An Introduction to Pathology, A.L. Kierszenbaum, 2002 - Connective Tissue, Chapter 4 pp118-129; Osteogenesis, Chapter 5 pp131-145
UNSW Virtual Slidebox Virtual Slidebox Phase 1
- Diaphysis - shaft
- Epiphysis - expanded ends
- Metaphysis - connecting region (between diaphysis and epiphysial line)
- Medullary Cavity - (marrow) cavity within the 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.
- (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.
Connective tissue covering the surface of bone (except articular surfaces).
Connective tissue lining inner surface of bone.
- 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)
- 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
- 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)
- 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
- 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.
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
- also called osteons
- Volkmann's canals - interconnect Haversian systems
- 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
- osteocytes extending cytoplasmic processes into canaliculi
- Additional Histology images: low | medium | high
Intramembranous ossification slides: Head (Neonatal) Rat H& Van Gieson
Human Fetal Head (12 week)
- 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
- 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)
- 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
- Virtual Slidebox of Histology (USA) Skeletal system
- e-radiography Ossification
- UWA Blue Histology bone
- Anatomy of the Human Body (H. Gray, 1918.) historical anatomy text Osteology
- Molecular Biology of the Cell Bone Is Continually Remodeled by the Cells Within It | Image: Figure 22-52. Deposition of bone matrix by osteoblasts | Image: Figure 22-56. The development of a long bone
- Molecular Cell Biology Mutations in Collagen Reveal Aspects of Its Structure and Biosynthesis
- The Cell- A Molecular Approach Steroid Hormones and the Steroid Receptor Superfamily
- Clinical Methods: The History, Physical, and Laboratory Examinations 100. Alkaline Phosphatase and Gamma Glutamyltransferase
- Endocrinology: An Integrated Approach by Nussey, S.S. and Whitehead, S.A. Endocrinology: Definition and causes of osteoporosis
- Developmental Biology 6th ed. by Gilbert, Scott F. Figure 14.13. Schematic diagram of endochondral ossification | Aging: The Biology of Senescence
- Pubmed ossification
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: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2021, April 18) Embryology Bone Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Bone_Development
- © Dr Mark Hill 2021, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G