Effects of in vitro conditions and in vivo thermal adaptation on viabilityof the earthworm (Eisenia fetida) coelomocytes

Coelomocytes of E. fetida were extruded from earthworms immersed for 1 minu te in fluid and treated either with an electric shock (5V) or 5% ethanol. T he two methods were equally efficient with regard to the number and viabili ty of coelomocytes retrieved and did not affect animal survival. Cell viabi lity was not affected by short contact with the extrusion fluids of wide ra nges of osmolarities (10-1600 mOsm) and pH (3-11). In contrast, extreme pH (especially 1 1) and osmolarities (especially 22 and 600 mOsm) impaired cel l viability during a few hours of in vitro incubation. Cell survival was be st in L-15 medium at the neutral pH and at the osmolarity characteristic fo r terrestrial animals (285-320 mOsm). Coelomocyte viability after 7 hr in v itro incubation at 0, 10, 22, and 37 degrees C was always the lowest at 37 degrees C. Cells extruded from animals maintained at room temperature were the best vital at 22 degrees C. Viability of the cells transferred from 22 degrees C to 10 degrees C for one week only was best at 10 degrees C and eq ually good at 0 degrees C and 22 degrees C. In vitro viability of cells ret rieved from earthworms maintained at 10 degrees C for 2 or 3 weeks was sign ificantly higher at 10 degrees C and 0 degrees C than at 22 degrees C. This indicates that a relatively long-lasting (more than one week) in vivo adap tation to cold is necessary to improve coelomocyte viability at low tempera tures.