This 30-minute program, the 5th in our Visual Histology DVD series, opens with Dr. Moran giving blood at the Blood Bank. While getting the needle, Dr Moran explains blood is the first tissue type we’ve studied that is a fluid. In the clinic, we see a clear container filled with a pint of blood which has separated into two different-colored layers: A straw-colored upper layer containing plasma and white blood cells — leukocytes —and a dark-colored lower layer containing red blood cells, or erythrocytes.
Under the microscope, red blood cells are easy to identify; white blood cells take a bit more practice to recognize. We open with a crystal-clear illustrated diagram that outlines the two major categories of leukocytes: the granulocytes (that have conspicuous granules) and the agranulocytes (that don’t).
We then look at a series of light and electron microscopic images that clearly show the morphology of red and white blood cells. Dr. Moran gives an informative, easy-to-understand narrative explaining the structure and function of each cell “type.”
Starting with a low-magnification blood smear, Dr. Moran explains that the most common stain used in haematology — Wright’s stain — contains Eosin, a dye that stains basic substances (like haemoglobin) red, and Methylene Blue, a dye that stains acidic substances (like nuclei) blue. He shows us that red blood cells — which, measuring 7 micrometers in diameter — act as handy “internal measuring devices” in tissue sections — outnumber white blood cells a thousand to one.
In an elegant high-magnification blood smear, Dr, Moran shows the three classes of GRANULOCYTES and explains how to easily identify them:
1) The neutrophils, or polymorphonuclear leukocytes (PMNs), which go to the connective tissues and become phagocytes;
2) The eosinophils, which go to the connective tissues, where they phagocytize antigen-antibody complexes; and
3) The basophils, with their prominent granules, which travel to the connective tissues to become mast cells. This slide is followed by matched light and electron micrographs that very clearly demonstrates the structure and function of each cell type.
Next, a high-magnification blood smear shows the two types of AGRANULOCYTES: Lymphocytes (35% of WBCs) and Monocytes (3%), and how to identify them. A lucid explanation of the function of these cells in the body’s defense systems is presented. This is clarified by a beautiful matched set of light and electron micrographs— from Moran & Rowley’s book, “Visual Histology” (available on this website) — that really “bends the nail over”.
The grand finale of this program is THE PRACTICAL EXAM, in which students can test their newly-acquired knowledge — and review for those exams!!
