The regeneration of supernumerary cockroach antennae

Abstract

ABSTRACT Grafting experiments performed on the basal scape segment of the antenna of Blabera craniifer give very similar results to those of corresponding grafts done on the legs of cockroaches and many other insects. If the antenna is amputated and replaced on the stump, it heals, while a 180°-rotated graft de-rotates and sometimes forms a symmetrical partial supernumerary. If the antenna is grafted on to the contralateral stump, one transverse axis of the graft is reversed relative to the host, and this results in the regeneration of a supernumerary antenna with host orientation from each of the two points of maximum incongruity between graft and host. Sometimes one double supernumerary forms midway between these points, and its orientation suggests that it results from a secondary fusion of the two supernumeraries. The similarity of these results to those of leg grafts suggests that legs and antennae have a similar general organisation of positional information and similar rules for cellular behaviour. Further, the two appendages may have the same set of positional values but have evolved different ways of interpreting it. Preliminary attempts to test this idea directly (by grafting between leg and antenna) were rather unsuccessful since only a few control grafts healed (poorly) and all rotated and contralateral grafts were eliminated.