Elimination by Hydra interstitial and nerve cells by means of colchicine.

Hydra treated with colchicine or Colcemid become depleted of 95-99% of their interstitial cells and derivatives of this stem cell: nematoblasts, nematocytes and nerve cells. A second treatment removes most or all remaining interstitial cells. The most effective treatment is an 8-h immersion of whole Hydra attenuata in 0.04% Colcemid or 0.4% colchicine. Interstitial cells are eliminated through phagocytosis by both ectodermal and endodermal epithelial cells. The endodermal digestive cells send processes through the mesoglea which engulf interstitial cells and retract them into the endoderm. The resultant hydra, though devoid of nematocysts, can be artificially fed: these animals grow and bud and can be used to study the behaviour and development of tissue lacking nerve and interstitial cells.