The Germline Marker Expressed in the Skin Layer of the Polychaete After Injury.

Nereidid polychaete is a homonomous metameric worm with a complete septum between each segment. Each segment has germ cells localized in the distal area of the parapodia. is also known to have high abilities of tissue regeneration; however, it is still unclear whether germ cells can regenerate in the healing tissue. To address this, we surgically operated the parapodia of an adult worm to remove germ cells from the segments and observed the germ cell regeneration using the germ cell genetic marker . At day 20 post-surgical operation of the parapodia in one side of the segment, we found that was expressed in the regenerating parapodia. We surgically operated the parapodia on both sides of the segment to remove the germ cells completely and it gave a similar result. However, before the expression of this gene marker in the regenerating parapodia, we observed that was expressed in cells in the skin layer of the worm just after surgical operations. These -positive cells were not observed in the un-operated worm. Our observations showed that germ cells of can regenerate even after the complete removal of germ cells from the defined habitat. The positive cells that appeared in the skin layer after the disappearance of germ cells may be involved in the regeneration of new germ cells.