Probably best to view them as a group, and discuss what you can or cannot identify. Answers will be posted in a few days. Until recently, it was thought that sebum probably had no important function in the human, but recently it has been shown that a significant amount of vitamin E is secreted in sebum , and since vitamin E is an antioxidant, it probably protects lipids of skin against oxidation. I showed a slide of a Langerhans cell that I said was probably presenting antigen to a closely associated lymphocyte. You will hear all about this complex subject in detail in next quarter's Immunology Course.
Macrophages are also antigen-presenting cells.
In blood vessels, leukocytes exist in a circulatory pool and a marginating pool. The latter pool consists of cells within small blood vessels that instead of being part of the central circulating bloodstream, adhere to vessel wall or cells found within vasoconstricted small vessels. All rights reserved.