![]() ![]() forms, function, and microscope techniques |
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Introduction:Mollusks, like many other invertebrates, have an open circulatory system that does not confine hemolymph to traditional vessels like veins, arteries, and capillaries. Instead, an open circulatory system will circulate hemolymph through a number of cavities and sinuses in various parts of the organism. In an oyster, the hemolymph is circulated in this way and can be readily found in the pericardial cavity that contains the heart. Within the hemolymph of the oyster there are three basic types of hemocytes that perform a wide variety of functions from defense to nutrient transport.A readily found hemocyte known as a granulocyte can make a very impressive showing under oil immersion light microscopy. These hemocytes appear to be filled with small "grains" and have long pseudopodia that extend from the outer surface of the cell. The pseudopodia are used for mobility and the capture of foreign bodies and disease causing organisms like dermo, Perkinsus marinus. |
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The procedure for harvesting hemocytes (and the video clips) were developed in collaboration with Dr. Gerardo Vasta of the UMBI Center of Marine Biotechnology in Baltimore along with Dr. Eric Schott, Dr. Jose A.F. Robledo, and Wolf Pecher. Their assistance has been an invaluable part of the translation of these practical techniques. The procedure is simple and requires only a few pieces of equipment. Viewing hemocytes is best accomplished under oil immersion with a 100x objective lens. Lower magnification will allow you to see them but not in great detail. Follow the procedure and you will be able to see these cells live on a glass slide.
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Materials:
Procedure:
Videos:
Wrap-Up:Compare and contrast the hemocytes with your own white blood cells and how the immune system of the oyster is different from that of a mammal.References:The Eastern Oyster. Victor S. Kennedy, Roger I.E. Newell, and Albert F. Eble, Eds. Maryland Sea Grant College, University System of Maryland, College Park, MD. 1996. Oyster Anatomy Laboratory, interactive lesson on oyster anatomy and how to properly "shuck" an oyster. Personal Communcation, Extracting hemocytes from the hemolymph of oysters, 2000, Drs. Gerardo Vasta, Eric Schott, Jose A.F. Robledo, and Wolf Pecher. Research by Dr. Gerardo Vasta:
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