Hemocytes of Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae): morphology of the cells in fresh blood and after cultivation in vitro

Abstract

Hemocytes of the forest tent caterpillar, Malacosoma disstria, were examined in blood films prepared from full-grown larvae, and in tissue cultures of blood cells maintained by serial passage in vitro up to 148 times. In fresh larval blood, five categories of hemocytes were identified as follows: prohemocytes, plasmatocytes, granular hemocytes, spherule cells, and oenocytoids. The granular hemocytes were the most numerous by far. In the tissue cultures, only three categories were found, prohemocytes, plasmatocytes, and granular hemocytes. and here the granular hemocytes were the least numerous. Each category in culture was autonomous and able to divide. Hemocytes in cultures were larger than the cells in fresh blood, and were mostly round.