1. View the slide on low magnification. In this view, you should be able to see the ductus thoracicus and the surrounding connective tissue.
2. Identify:
   • The lumen of the ductus thoracicus.
   • The epithelium lining the lumen.
   • The different layers comprising the wall of the lymph vessel.
     • The tunica intuna
     • The tunica media
     • The tunica adventitia
     • The divisions of each of the layers
   • The surrounding connective tissue.

   Name the epithelium lining the ductus thoracicus. List the layers and divisions of each layer comprising the wall of the ductus thoracicus. What tissue surrounds the ductus thoracicus?

3. View the medium and high magnification slides of the ductus thoracicus. In this view, cellular detail should be visible.
   • Identify the cells present in each layer of the lymph vessel.
   • Identify the cells present in the surrounding connective tissue.

   Name the cells present in each layer of the wall of the ductus thoracicus. Are the cells orientated parallel or perpendicular to the direction of flow in the vessel?

4. Make an annotated diagram of the complete ductus thoracicus, including the surrounding connective tissue. For a partial section of the wall of the ductus thoracicus, make a detailed drawing showing cellular detail and distribution of fibres. Indicate cross, oblique or longitudinal sections as appropriate. Add the function of each structure.

   Describe each layer in the wall of the ductus thoracicus. How is the elastic fibres distributed and arranged? How does the layers seen in a lymphatic vessel correlate and differ from that of arteries? And veins?

Reflection:

1. What is characteristic of each of the layers?
2. Describe the amount, distribution and arrangement of the elastic fibers in the thoracic duct.
3. Compare the structure of the thoracic duct with that of blood vessels.

Microscope

• Ductus thoracicus, stained to show elastic fibres
• Ductus thoracicus, stained to show elastic fibres