EYE FIELD OPERATIONS 



289 



TRANSPLANTATIONS: 



TRANSPLANTING THE ANLAGE 



When the aniage is transplanted to a slightly older host, the conditions for the ex- 

 pression of any self-differentiation are somewhat different from those of an isolation 

 culture. However, the nutritive factors are generally the more favorable, and axial 

 relations can be determined. These operations are best on Urodele embryos. * 



1. Decapsulate some Urodele embryos in stage #14, and locate the eye field at 

 the anterior limit of the medullary plate (see figure on following page). 

 Stain the entire donor in 1/500,000 Nile Blue Sulphate. 



2. Prepare host larvae by excising the ectoderm, mesoderm and some of the 

 underlying yolk on the lateral belly region of stage #24 or #25 (see figures 

 below). The prepared wound should be slightly larger than the prospective 

 graft. 



3. On the point of a needle transfer from the stained donor 



a. The right optic aniage' 



b. The median transverse neural fold and medullary plate 



c. The entire (anterior) optic aniage (A-C-B in figure above) 



on the prepared host sites. Hold in place with Brlicke, or by hand, for a 

 few minutes until the graft becomes adherent. The vital dye will indicate 

 the limits of the graft. 



Schema of a typical experiment, showing the relations of 

 the transplanted median and left lateral strips of neural 

 plate and their orientation in the hosts. R, right; L, left. 



From Adelmonn 1930: Jour. Exp. Zool. 57:223. 



By recording the exact shape of the graft at the time of excision, it will be 

 possible to record the axial relations of the graft in the host site. 



TRANSPLANTING THE OPTIC VESICLE AND LENS ECTODERM 



The most complete study of heteroplastic eye transplantations has been made by Harrison 

 (1929) and recently Eakin and Harris (1945) have determined the degree and onset of tis- 

 sue incompatibility in xenoplastic transplants using the eye as the test object. As with 

 other organ anlagen, eye transplants between the various species of Amblystoma are 

 most successful and instructive. Since there are intrinsic differences in growth rate, 

 these become exaggerated in such heteroplastic transplants. 



Harrison (1929) pointed out that homotopic transplantations (in order to produce functional 

 eyes) will succeed best at stages #27 to #29 at which time the vesicle is well marked off 

 from the stalk and mortality is consequently lower. If, however, it is desired that the 

 mesodermal and mesectodermal tissues be eliminated from the study, he suggests using 

 stage #21, just after the closure of the neural folds. In any case, after making a circular 



* Follow the standard operative procedures described elsewhere. See Schwind (1937) for results with the Anura. 



