Cells released in vitro from the embryonic yolk sac of the stick insect Carausius morosus (Br.) (Phasmatodea : Heteronemiidae) may include embryonic hemocytes

The embryonic yolk sac and the adult dorsal Vessel df the stick insect Cara usius morosus (Br.) (Phasmatodea: Heteronemiidae) were shown to release a n umber of cells that appear morphologically similar to circulating adult hem ocytes. Like adult hemocytes, these cells reacted positively when tested fo r both phenoloxidase activity and a monoclonal antibody specifically raised against a vitellin polypeptide. Based on this evidence, it is suggested th at yolk sac-released cells behave as potential embryonic hemocytes. A model is thus proposed whereby the yolk sec might host a number of hemopoietic s tem cells on their way to the dorsal vessel, and in so doing, it may tempor ally act as an embryonic hemopoietic organ. (C) 1998 Elsevier Science Ltd. Air rights reserved.