Fig. 4. Process of second axis formation in a hypostome-contact graft. (A) Seventy-two hour graft with an emerging second axis. (B) One hundred and twenty hour graft with tentacles forming at the apical end of the emerging second axis. In both A,B, the India Ink stained donor tissue (black dots) is on the left with the arrowheads indicating the border between donor and host. The arrows in A,B indicate emerging (A) or developing (B) tentacles. Samples in A,B were stained with the TS-19 antibody to identify the emerging and developing tentacles (Bode et al., 1988). (C) An induced second axis (head and body column facing left) after removal of the inducing donor tissue. The donor (on the left in A,B) was labeled with India Ink while the host was labeled in C. Arrowheads indicate the border between donor and host, and arrows indicate emerging or developing tentacles.
