KETTERING, R.D.; JOHNSON, G.P.; WOLFE, A.F.*; Lebanon Valley College; Lebanon Valley College; Lebanon Valley College: A histological and ultrastructural study of Artemia hemocytes

Crustaceans, as well as other invertebrates and vertebrates, usually have several different types of blood cells within their vascular fluid. Artemia franciscana, an anostracan crustacean, has a single type of granular hemocyte in its hemolymph. Using various types of staining and microscopic techniques and gel electrophoresis, this study focused on on the structure of these hemocytes, especially the composition of the granules and their possible functions. The hemocytes are approximately 9 �m in diameter and are usually disc-shaped with a smooth surface; however,they can develop an abundance of pseudopodia. They possess an ovoid nucleus that sometimes appears lobed; contain a large number of randomly distributed 3 �m granules; and have many mitochondria located peripheral to these granules. The granules are surrounded by a single membrane and contain a homogeneous material that stains positive for protein and elastin. At the TEM level the contents of granules appear to consist of at least two different components; one is much more electron dense. Gel electrophoresis indicated several bands of these proteins with molecular weights of 92,000, 125,000, 155,000, 170,000, and 200,000 daltons. Artemia hemocytes have been shown to form aggregates with each other to produce clots during wound healing. It has been suggested that these cells also play a role in phagocytosis of foreign material. In our study these hemocytes did form aggregates with masses of the cells remaining intact and adhering tightly to each other. At the TEM level these cells always showed intact cell membranes, indicating a surface to surface attachment. Neither the granules nor their contents exhibited any demonstrable antimicrobial activity.