Cells from four species of Lepidoptera larvae known to be susceptible to several intracellular pathogens were cultured in vitro. Undifferentiated cells had the greatest potential for growth and survival. Imaginal wing disc explants formed extensive monolayers as a result of cell migration and mitosis. Mitoses were abundant in prohemocytes but not in other types of hemocytes. Differentiated larval tissues were unsuitable sources of cells for continuous culture. Migration of cells from these tissue explants was limited, and those cells which isolated themselves from the explant did not divide.
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Cell culture has often been suggested as a “tool” for the study and propagation of intracellular microorganisms associated with insects. Through their evolutionary descent these microbes have become extremely dependent on certain cellular environments for their growth and development, and any attempt to infect cultured cells with them must take this into consideration. Aspects of host-pathogen relationships may be amenable to study and interpreta-tion if methods of directly observing the developing microorganisms can be devised. Because of the differing histotypic-and host-specificities of the organisms, there is need to develop techniques which will permit the continuous cultivation of a greater variety of insect cell types. We have 1 This is paper No. 7011, Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul, Minnesota. The work was supported in part by U.S. Public Health Service Research Grant No. AI 00961, from the National Institute of Allergy and Infectious Diseases of the.National Institutes of Health.