Equipment and safe technique
Dissection makes it possible to inspect the larger components of animal gas exchange systems. Common tools include a scalpel, dissecting scissors, forceps and dissecting pins.
- Use suitable protection, including a lab coat, gloves and eye protection, when handling biological material.
- Clean, sharp instruments make controlled cutting easier and help avoid unnecessary tissue damage.
- Keep hands clear of blade edges and make scalpel cuts in a direction away from the body.
- Specimens should be obtained responsibly and disposed of by the appropriate laboratory procedure.
Structures that can be examined
1
Mammalian lungs
- The trachea is distinguishable because rings of C-shaped cartilage reinforce it.
- Its cartilage is relatively tough, so scissors may be useful when opening it.
- The bronchi can be traced into the lungs and their finer bronchioles followed through the tissue.
The alveoli themselves are difficult to resolve by eye. Instead, the many air-containing spaces give the cut lung tissue a noticeably spongy texture.
2
Bony fish gills
Lifting the operculum reveals the gills positioned at the sides of the head.
- A gill arch forms the firm support from which a complete gill can be removed.
- The attached gill filaments are visible without magnification as numerous fine projections.
- The much smaller lamellae need a microscope to be examined clearly.
3
Insect tracheal system
- Pin a sufficiently large insect securely onto a dissecting board.
- Make a longitudinal opening through the abdominal exoskeleton to expose the internal structures.
- Introduce saline solution into the opened abdomen; the tracheae can then be recognised more readily as shiny, silver-coloured tubes.
- Suitable pieces of trachea can be isolated and transferred for microscopic examination.