1. Examine the cross-section and define the main types of blood vessels in the microcirculatory bloodstream within the connective tissue filling in the space between larger blood vessels and a nerve (vascular-nervous bundle):
- capillaries - are the finest blood vessels, their diameter is 3-12 micrometers (internal duct – 1-2 erythrocytes) lined with endothelium, the outer layer is formed by pericytes;
- arterioles - are larger blood vessels (diameter 50-100 micrometers) lined with endothelium, their tunica media contains smooth muscle cells placed circularly;
- venules - are blood vessels (diameter 30-100 micrometers), have a larger internal duct than capillaries; unlike arterioles venules don’t have a layer of smooth muscle cells in the walls;
- lymphocapillaries - are larger blood vessels having thin walls (diameter 30-200 micrometers) which lack blood corpuscles in the lumen; lined with large endothelial cells; free from smooth muscle cells;
- space between micro-vessels is filled with loose connective tissue and adipose tissue.
3. Draw and point out:
1 - capillary,
2 - arteriole,
3 - venule,
4 - lymphocapillary,
5 - loose connective tissue,
6 - adipose tissue.
4. Define and write significant features of the preparation