^10 EXPERIMENTAL FISH EMBRYOLOGY 



Fig. 1. Ail early stage In Induction in Fundulus, drawn fii hours after operation. The 

 first visible effect of dorsal lip implantation in Fundulus is concentration of 

 cells in the vicinity of the graft; here host cells (H) stained with Nile blue sul- 

 phate aggregate in the region of the graft (O) stained with neutral red. P, primary 

 embryo. 



Figs. 2 and 3. Two percli eraoryos (I) induced by dorsal lip grafts implanted into the edge 

 of the blastoderm 180° away from the primary dorsal lip; drawn 2 and 5 days after 

 operation, respectively. P, primary embryo. Fig. 3 drawn by Miss L. Krause. 



Fig. 4. Axial structures (I) induced from the extra-embryonic epithelium of a Fundulus 



egg by implantation of young dorsal lip into the edge of the blastoderm; drawn 21i 

 hours after operation. 



Fig. 5. Embryonic structures (I) induced in Fundulus by implantation of a dorsal lip 



material into extra-embryonic epithelium; drawn .23 days after operation. E, ear. 



Fig. 6. Perch embryo (I) induced by dorsal lip implanted into extra-embryonic epithelium; 

 drawn li days after operation. This embryo was probably a lateral hemi-embryo; 

 somites were formed on one side only. 



Figs. 7 and 8. Two stages in the development of a Fundulus embryo induced by the implanta- 

 tion of very young dorsal lip into a very young gastrula; drawn at 18 hours and 3i 

 days after operation. The right part of the graft, which liad been stained with Nile 

 blue sulpliate, failed to invaginate and formed a knob (0) at the right side of the 

 developing Induced embryo; as a result the induced embryo (I), although two ears 

 were formed, was a lateral liemi-embryo with somites present only on the left side. 



Fig. 9. Fundulus embryo (I) induced by a dorsal lip graft implanted into the edge of the 

 blastoderm; drawn 3 days after operation. The ears and right fin of the Induced 

 embryo are formed posterior to the corresponding structures in the primary embryo 

 (P). 



Fig. lu. Head structures of Fundulus (I) induced by a dorsal lip graft which was original- 

 ly implanted into extra-embryonic epit)ielium but which shortly after implantation 

 became incorporated into tiie primary embryonic shield; drawn 3 dasy after operation. 



Fig. 11. Fundulus embryo (I) induced by the implantation of very young dorsal lip; the 

 graft was incorporated into the primary embryonic shield. Drawn 22 hours after 

 operation. 



Fig. 12. Somites (I) induced by a dorsal lip graft implanted into the primary embryonic 



shield; 1 day after operation. The accessory somites persisted for 2 days and sub- 

 sequently were absorbed into the host; compare embryo shown in Fig. 6, where somites 

 induced in an extra-embryonic region exhibited a different segmentation from the 

 host's. 



Fig. 13. A dorsal lip graft implanted anteriorly in the embryonic shield was partially 

 absorbed into the forebrain, wltli the result that this structure has wider walls 

 than normal . 



Fig. 14. A graft of cells removed from a lateral part of the shield formed brain (G) in 

 the mesencephalic region of the Iiost. HOL, optic lobes of host. 



F'lg. 15. A perch embryo In which dorsal lip implanted into the embryonic region was trans- 

 formed to brain; drawn 6 days after operation. 



(From Oppenhelmer I956: Jour. Exp. Zool. 72:1+09) 



