BIPOLAR HEAD REGENERATION IN PLANARIA INDUCED BY CHICK EMBRYO EXTRACTS

¹ Department of Biology, State University of New York at Buffalo, Buffalo, New York

1. Decapitated planaria, Dugesia dorotocephala, exposed to head and tail centrifugal supernatants for nine days do not exhibit inhibition of brain regeneration. The experimental and control worms had brains of equal sizes.

2. A significant number of bipolar heads regenerated in small pieces from the posterior region of starved worms which were cultured in chick embryo extract and chick embryo extract ultrafiltrate.

3. Chick embryo extracts produce a stimulation of DNA synthesis in pieces of starved worms which were cut into anterior, middle and posterior sections. There is a greater stimulation at the posterior levels which can give rise to bipolar heads. This stimulation of DNA synthesis is thought to reflect an increase in cell division at these levels caused by the chick embryo extract.