Proportion regulation in the planarian, Dugesia tigrina following regeneration of structures

Planarian regenerates with abnormal body proportioning were followed after structure formation in order to determine if body proportion will 'normalize' over time. Results show proportioning will occur following structure formation since the pharynx in regenerates with proportionally larger heads and prepharyngeal area moved anteriorly over time. This occurred regardless of whether regenerates were provided with a normal feeding regime which allowed for an increase in body area or if they were on a maintenance diet which did not permit growth. An examination of mitotic indices did not demonstrate significant differences in the level of mitotic activity between pre- and postpharyngeal regions. It is concluded that the 'normalizing' of proportion in these abnormal regenerates does occur, but the process by which it occurs is not solely explained through normal growth.