Dirofilaria immitis is a filarial parasite that is spread by mosquitoes and causes heartworm disease in dogs and pets. Our area of interest is to study the developmental regulation of D. immitis inside its arthropod host and to understand the role that ecdysteroids play in this process. This picture was taken with the Hitachi TM-1000 scanning electron microscope and shows a D. immitismicrofilaria that has developed into the "sausage" stage after in vitroincubation with mosquito cells. [Image by: Cathy Shang Kuan - Roger Prichard Lab]