Encapsulation response of Ciona intestinalis (Ascidiacea) to intratunical erythrocyte injection. I. The inner capsular architecture

: Previous studies on the ascidian Ciona intestinalis have shown that an encapsulation response is experimentally induced by inserting vertebrate erythrocytes into the tunic, which initiates a massive inflammatory cell infiltration to isolate the injured area. Several hemocytes contribute to capsule formation, destruction of the foreign cells, tunic regeneration, and wound healing. The fine features of some inflammatory cell types are described although the complete capsular structure is not yet reported. Accordingly, the present investigation further examines various aspects of this cellular reaction against erythrocytes and, for the first time, presents the involvement of extratunical circulating hemocytes and mantle epithelium in capsule formation.