UNSW Cell Biology

Medicine: Ageing and Endings: Bone Development, Structure

Introduction

Bones give us our shape, allow movement, store calcium and are the source of blood cells. There is a lifelong dynamic balance between bone deposit by osteoblasts and bone erosion by osteoclasts.

From embryology we know there are 2 main ways that bones initially form and this process occurs through postnatal development. Our height is regulated by growth in the long bones which continues through childhood puberty and into early adulthood. As an adult growth in length slows, though remodelling continues, and the process is under hormonal regulation.

Expert Tutorial - Just added Bone FAQ Page

Endochondral and Intramembranous Ossification in the Embryonic Head

This practical class has 2 main parts. The first part will look at normal bone formation and its cellular and non-cellular structure. The second part will look at abnormal bone, metabolism and disease. The Practical involves studying selected slides from the Virtual Slide Box. Additional linked pages and resources provided are for self-directed learning.

Objectives

Understand the development of bone
Understand the histological appearance of bone
Identify the structures and cell types within bone
Identify bone damage and abnormal bone

Resources

A&E Class Notes

Link to class notes for this Lab AEPrac1Notes.pdf

UNSW Virtual Slidebox

Link to histology slides used in this current Practical - Virtual Slidebox Phase 1

Virtual Slidebox of Histology (USA)

Link to normal histology slides used in this current Practical - Skeletal system

Textbook

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

Pathology

Virtual Slidebox of Histology

Paget's disease of bone is a disorder of uncertain aetiology, resulting in excessive bone resorption and haphazard new bone formation. Examine the virtual slide labelled Paget's disease of bone and note the features that indicate excessive resorption, as well as abnormal new bone formation.

Do you notice any other abnormal features in the marrow spaces?
What are the likely clinical consequences of this disease?

Endochondral Ossification

Developing Limb	Developing Vertebra

Intramembranous Ossification

Human Fetal Head (12 Week)


Lateral view	Medial view

Note the obvious intramembranous ossification that is occuring in the cranial vault region. Histological stains differentiate between forming bone (red) and cartilage (blue). (More? UNSW Embryology - Human 12 Week Fetus)

Bone Cells

Osteoblasts - derive from osteogenic stem cells and line surface of bone, secrete organic matrix of bone (osteoid), converted into osteocytes when become embedded in matrix (which calcifies soon after deposition) (Google- osteoblast images)

Osteoclasts - bone-resorbing multinucleated macrophage-like cells, 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)

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)

Histology

Below are links to useful Histology resources on bone histology.

UWA Blue Histology Skeletal Tissues - Bone
University of Kansas Histoweb Bone
Loyola University Medical Education Network Part 9: Specialized Connective Tissue: Cartilage and Bone | Part 10: Endochondral Ossification
UNSW Embryology Cartilage and Bone

Student Guide

Brief Study (1-15 minutes)

Start by looking at the online textbooks. These links will give you an introduction to bones and some images.

Detailed Study (15-30 minutes)

Next- more detailed online resources related to bone development and regulation. Includes a link to a complete set of lecture slides on bone development and bone structure/function.

In Depth (+30 minutes)

Then- look at the structure and function of Bones. Includes links to review articles and animations.

Search Links

Search NLM Online Textbooks- "Bone"

Molecular Biology of the Cell

Molecular Cell Biology

The Cell- A molecular Approach

UNSW Cell Biology

Medicine: Ageing and Endings: Bone Development, Structure

Introduction

Objectives