EXPERIMENTAL FISH EMBRYOLOGY 



395 



3. 



Dissect out of the donor the region comparable to the amphibian dorsal lips, 

 1. e. , the margin of the germ ring from which arises the embryonic shield. ' 

 Clear it of all adherent yolk. Use sharp and sterile steel needles. It will 

 help to follow the graft if the entire donor is previously stained in 1/10 000 

 Nile Blue Sulphate. 



Prepare the host for the graft, using two different sites in as many hosts. 

 Operate in double Standard (Holtfreter ' s) Solution, or stronger. 



a. Loosen the embryonic shield on one side, using sharp, steel needles. 

 The cells will tend to grow together rapidly, and will hold any graft in 

 place. Insert the excised dorsal lip material, pushing it beneath the 

 margin of the embryonic shield. 



b. Loosen some superficial cells of the extra-embryonic blastoderm at 

 some distance from the embryonic shield, and quickly insert the excised 

 dorsal lip nnaterial. 



After the wound has healed and the graft seems to be held intact, transfer 

 the embryo (by wide-mouthed pipette) to a covered #2 Stender containing 

 sterile, normal (isotonic) medium for that egg. Culture it for a few hours 

 to as many as 7 days, depending upon the success of the take and health of 

 the embryo. 



Localization in the nerve keel of 

 the late gastrula. Cells removed 

 from the region A differentiate 

 when grafted on extra -embryonic 

 membrane to form optic lobe, 

 cells from the region C to form 

 spinal cord. A defect in the 

 region B resulted in a deficiency 

 in the region of Mauthner's cell. 



(From Oppenheimer 1936: 

 Jour. Exp. Zool. 73:405) 



An embryo in which 180° germ 

 ring from an early gastrula has 

 formed caudal fin dorsal to the 

 brain of the host. Fixed 8 days 

 after operation. 



(From Oppenheimer 1938: 

 Jour. Exp. Zool. 79:185) 



TRANSPLANTATION EXPERIMENTS BY DR. JANE OPPENHEIMER 



Fig. 1. An early stage in induction in Fundulus, drawn 6-1/2 

 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 sulphate aggregate in the region of the 

 graft (G) stained with neutral red. P, primary embryo. 



Fig. 2 and 3. Two perch embryos (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. 



(From Oppenheimer 1936: Jour. Exp. Zool. 72:409) 



