296 



EYE FIELD OPERATIONS 



TRANSPLANTING THE OPTIC VESICLE AND LENS ECTODERM 



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

 son (1929) and recently Eakln and Harris (19^5) have determined the degree and onset of 

 tissue 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 (I929) pointed out that homotoplc transplantations (in order to produce func- 

 tional 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 incision around the eye region the optic vesicle at stage #21 (or cup at stage 

 #28) is readily separated from its surroundings and the optic stalk may be cut close to 

 its origin from the brain. The whole may then be reioved without disturbing any of the 

 adjacent mesodermal (mandibular arch) or mesectodermal (ganglion crest) structures. When 



Eyes transplanted from Amblystoma 

 tigrinum to the belly region of 

 Amblystoma puiictatum at stage #29. 



Amblystoma eye transplanted 

 to the region of the ear. 



(From Detwller 1914-5: 

 Jour, Comp. Neur. 82:ll+5) 



reciprocal transplants are made it must be remembered that the eye vesicle of the A. punc- 

 tatum embryo, at comparable early stages, is much larger than that of A. tigrinum. In 

 consequence it is more difficult to place the punctatum graft in the A. tigrinum host than 

 vice versa. The A. tigrinum optic vesicle, at a comparable stage, is smaller than that of 

 A. punctatum, but it grows more rapidly and soon surpasses the A. punctatum eye in size 

 (see illustrations from Harrison's paper). 



Procedure :* (Transplants between A. punctatum and A. tigrinum embryos or from 

 A. mexicanum to A. punctatum stages #27 to #29.) 

 A. First attempt to transplant the entire optic vesicle with overlying ectoderm 

 from one species (Amblystoma) to another Into an heterotopic region, i.e., to 

 the lateral belly region. (See photographs.) 



* Follow the usual operative procedures described elsewhere. 



