Earthworm cells in culture. Phase contrast [M. Battaglia, C. Davoli. 1997 - Long-term tissue culture of the earthworm Eisenia foetida (Annelida, Oligochaeta). In: K. Maramorosch, J. Mitsuhashi. Invertebrate Cell Culture: Novel Directions and Biotechnology Applications. Science Publishers, USA, p.261-268].