Fig. 3. The posterior neural plate generates mesoderm after posterior neuropore closure. (A) 10.5 d.p.c. tail piece labelled with DiI in neurectoderm and cultured for 48 hours. Labelled descendants are present in neurectoderm (asterisk) and posterior mesoderm (arrow). (B-D) successively more posterior transverse sections of a second embryo, showing label in neurectoderm (asterisks), mesoderm (arrow) and in the posterior, but not more anterior, notochord (arrowheads in B,C).