LIVER

Slide 142 (human liver) is especially good for the well-preserved components of portal areas and for the presence of numerous mast cells. Notice the walls of arteries, veins, lymphatics and bile ducts in the portal areas. Then, at low magnification, look in the loose connective tissue surrounding the largest portal vessels and find some cells that are definitely larger and darker than any of the others in the area. These are mast cells. Viewed with higher power, they show very definite dark, cytoplasmic granules.   Recall what these cells secrete. Mast cells are often found near blood vessels and act as sentinels for the reappearance of recognized antigen, which they will serve to render harmless via their inflammatory response.

Another feature in this slide to watch for is the presence of blood vessels containing unusual numbers of white blood cells . Many are clearly neutrophils, with their lobulated nuclei; some are eosinophils with bright pink granules; many look like immature leukocytes, as if there were some blood problem in this individual.