Undecalcified bone histology provides important information for a variety of clinical and research applications. It is technically challenging, particularly with large size specimens. This video illustrates the process of producing good quality sections and demonstrates the technical difficulties and methods with which to overcome them.
Undecalcified bone histology demonstrates the micro-architecture of bone. It shows both the mineralised and cellular components of bone, which provides vital information on bone turnover or bone formation and resorption. This has tremendous importance in a variety of clinical and research applications. It yields beautiful images1 and allows for techniques such as fluorochrome assessment and histomorphometry2. Fluorochrome analysis is a technique where fluorescent dyes that bind to calcium are injected at a particular time point, which allows for quantification of the amount of mineralisation at that given time. Histomorphometry is a process of bone quantification at the microscopic level.
Performing undecalcified bone histology is technically challenging, particularly with large size specimens. It requires variations in technique from those used in standard paraffin embedded histology. This video illustrates the process of producing good quality sections and demonstrates the technical difficulties and methods with which to overcome them. Specimen preparation, fixation and processing are achieved with a manner similar to other soft tissues, however due to the density and lower permeability of bone considerably longer fixation and processing times are required, often taking several weeks. Embedding is achieved using a supporting medium with similar or equal hardness and density to the bone such as methacrylate- based resins, but unlike paraffin infiltration and embedding, this is an irreversible step. Sectioning can be achieved by grinding which produces a thicker section, which is optimal for studies such as fluorochrome analysis. This is best achieved using a diamond blade on a macrotome. Alternatively, thinner sections can be produced for light microscopy and this is achieved using a sledge microtome with a very sharp blade. The sledge microtome provides the additional strength and stability required for large, hard blocks. Resin embedded sections can be stained with a variety of stains, which are demonstrated.
The authors would like to acknowledge the assistance of Ms Sue Connell for her expertise in resin embedding and Ms Stephania Tombs for her laboratory expertise. The authors would like to thank Professor Frank Kandziora and Dr Marie-Anne Polboth for their advice.
Goldner’s Trichrome stain
1. Weigert’s iron hemotoxylin (DeGroat)
a) Hemotoxylin solution | |
Hemotoxylin | 1g |
Absolute Alcohol | 100mL |
b) Iron Solution | |
30% aqueous ferric chloride | 4mL |
Hydrochloric acid (concentrated) | 1mL |
distilled Water | 95mL |
Filtered and added to equal volume of hemotoxylin immediately before stain used.
2. Ponceau-fuchsin-azophloxin stock solutions
a) Ponceau de xylidine solution | |
Ponceau de xylidine | 0.75g |
acid fuchsion | 0.25g |
Acetic Acid | 1mL |
mix, and add distilled water (100mL) | |
b) azophloxin solution | |
Azophloxin | 0.5g |
Acetic acid | 0.6mL |
mix, and add distilled water (100mL) | |
c) Final working stain solution | |
Ponceau-fuchsin solution | 5-10mL |
Azophloxin | 2mL |
0.2% acetic acid solution | 88mL |
3. Light Green Solution
Light Green | 1g |
acetic acid | 1mL |
Mix, and add distilled water (500mL) |
4. Phophomolybdic acid-Orange G solution
Phosphomolybdic acid | 3g |
Orange G | 2g |
Dissolve in 500mL of distilled water and add crystal thymol. |
Von Kossa Stain
1% aqueous silver nitrate |
2.5% sodium thiosulfate |
1% safranin O |
Alcian blue stain
Alcian blue 8GX | 1g |
3% acetic acid solution | 100mL |
Hemotoxylin and Eosin stain
a)Harris’s hemotoxylin | |
Hemotoxylin | 2.5g |
Absolute alcohol | 25mL |
Potassium Alum | 50g |
distilled water | 500mL |
mercuric oxide | 1.25g OR |
Sodium iodate | 0.5g |
Glacial acetic acid | 20mL |
b) Eosin solution | |
Commercially produced Eosin was used. |
All stain dye powders are Gurr dye powders.
All reagents are analytical reagents, and not Lab reagents
Fluorochromes
Manufacturer |
Fluorochrome | Catalogue Number |
Sigma-Aldrich, Sydney | Calcein Green | C0875 |
Sigma-Aldrich, Sydney | Alizarin Complexone | A3882 |
Intervet Australia, Victoria | Oxytetracycline (off the shelf antimicrobial drug) |
Tradename; Engemycin 100 |