290 



EYE FIELD OPERATIONS 



incision around tne eye region the optic vesicle at stage #21 (or cup at stage #Zb) is read- 

 ily separated from its surroundings and the optic stalk may be cut close to its origin from 

 the brain. The whole may then be removed without disturbing any of the adjacent meso- 

 dermal (mandibular arch) or mesectodermal (ganglion crest) structures. When recipro- 

 cal transplants are made it must be remembered that the eye vesicle of the A. punctatum 



Eyes transplanted from Amblystoma 

 tigrinum to the belly region of 

 Amblystoma punctatum at stage #29. 



J 



(From Detwiler 1945: Jour. 

 Comp. Neur. 82:145) 



Amblystoma eye transplanted 

 to the region of the ear. 



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

 quence 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. ) 



1. 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. ) 



2. When "1" has been accomplished, transplant the entire optic vesicle -and over- 

 lying ectoderm of another donor to the excavated optic region of another host 

 (homotopic and heteroplastic transplant). It would be best to make the first 

 attempts from A. tigrinum to A. punctatum. 



* Follow the usual operative procedures described elsewhere. 



