The culture of planarian tissues in vitro.

Abstract

This preliminary paper is devoted to a description of the technique and some suggestive results of the culture in vitro of the tissues of the flatworm, Planaria dorotocephala. Practical sterilization of the material has been accomplished by exposing the worms, in a small amount of water, to ultra-violet radiation from a quartz mercury arc lamp at a distance of 35 cm. during 4. minutes. After such an exposure the bacteria associated with the worms are practically all killed or prevented from reproducing, without injury to the worms. The hanging-drop, as well as the petri-dish technique were used for the tissue cultures.

Buffer solutions composed of the common physiological salts, in order to be tolerated by the Planarian explants, must be between 1/8 and 1/25 the concentration of chick serum. The optimum concentration of Planaria is 1/10 to 1/12 the chicken concentration. Intact worms, however, tolerate indefinitely all concentrations between well-water and buffer solutions containing from 1/4 to 1/5 the salt-content of vertebrate-isotonic solutions. The organ of osmotic regulation seems to be the external epithelium of the worm.

In hanging-drop cultures the cells survive in fluid media for as long as 10 to 15 days; they are pseudopodially active, and show some cell division, but not active, sheet-like proliferation. When support and tension are afforded to the explant by the addition of a drop of agar, a conspicuous sheet-like outgrowth of parenchyma may be seen within 12 hours. The cells will migrate along fine silk strands, but do not spread in sheets. Under certain conditions, cells in petri dish cultures may survive as long as 64 days.

Serum or tissue extracts of the following animals have been introduced into the culture media: tapeworm, clam, snail, isopod, frog, sheep, without injurious effect upon the explant.