Method of Introducing Tritiated Thymidine into the Tissues of Hydra

Abstract

Although normal hydras resist the uptake of tritiated thymidine into thei tissues, regenerating forms contain a very heavy label in interstitial cells, epithelio- muscular cells, and digestive cells of the gastrodermis if the animals are allowed to regenerate in a medium containing the isotope. Preliminary results suggest that during early regeneration active wound repair is not effected by interstitial cells which divide and then begin to differentiate, but through differentiation of interstitial cells which are nondividing or which have partially begun to differentiate. Dividing interstitial cells probably function to restore the animal's original embryonic reserve.