Fig. 6. Observations of PAT cell migrations (anterior is downward). (A) A competent larva viewed ventrally. Note extended papillae (pap), two layers of tunic (lt, larval tunic; jt, juvenile tunic), rounded blood cells (*) within the hemocoel (h). (B) 15 minutes after induction of settlement with 50 mM KCl filtered sea water. Note retraction of the papillae, an anterior cone of PAT cells has extended into the tunic space (black arrowhead), the anterior region has flattened and the tunic has begun to expand anteriorly. (C) 25 minutes after induction, note the anterior tunnel through the tunic and the PAT cell clearly migrating through the tunnel (black arrowhead). (D) 45 minutes after induction, the migrating PAT cell is now outside of the juvenile tunic. Under natural conditions the larval tunic is molted, leaving the migrating PAT completely exposed to the external environment. Also note the continued migration of rounded blood cells across the epidermis in the anterior (black arrowhead).

Return to article