Bone Development: Difference between revisions
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==Histology Stains== | ==Histology Stains== |
Revision as of 14:29, 21 September 2009
Introduction
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.
For more development background see the Science Lecture - Musculoskeletal Development
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
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
- Compact Bone - Adult Bone , Adult (Ground, TS) Human Alizarin Red | Bone (Ground, LS) Human Alizarin Red
- Compact Bone Rib Decalcified rib, bone marrow
- Endochondral ossification Developing bone | Bone, Developing (LS, Femur) Cat H&E
- Intramembranous ossification Head (Neonatal) Rat H& Van Gieson
Bone Structure
Compact bone
- 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 surface of bone.
Endosteum
Connective tissue lining inner surface of bone.
Bone Cells
Osteocytes
- mature bone-forming cells embedded in bone matrix
- derive from osteogenic stem cells the osteoprogenitor cells that differentiate to form pre-osteoblast then osteoblasts maturing to an osteocyte
- osteoprogenitor cells - line the inner and outer surfaces of bone
- osteoblasts and osteocytes - secrete organic matrix of bone (osteoid), converted into osteocytes when become embedded in matrix (which calcifies soon after deposition)
Osteoclasts
- 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 secreted into this space by osteoclasts dissolves calcium phosphate crystals (give bone rigidity and strength) (Google- osteoclast images)
- do not mistake for megakaryocytes, found in bone marrow not associated with bone matrix.
- megakaryocytes are also multi-niucleated and form platelets
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. (Google- bone matrix images)
Haversian Systems
- 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 and canaliculi
Endochondral ossification
Endochondral ossification slides Developing bone | Bone, Developing (LS, Femur) Cat H&E
Intramembranous ossification
Human Fetal Head (12 week)
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)
Links
- Original class notes
- UNSW Virtual Slidebox Virtual Slidebox Phase 1
- Virtual Slidebox of Histology (USA) Skeletal system
- Lecture - Musculoskeletal Development
Other Textbooks
- 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 ItImage: 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. Aging: The Biology of Senescence