37. EYE FIELD OPERATIONS 



PURPOSE: To determine the anlage for the optico-ocular apparatus; the limits of regen- 

 eration of parts of the eye field; the time and extent of self-differentiation; the induc- 

 tive relations; and the extent of experimentally induced cyclopia. 



MATERIALS; 



Biological: Anuran embryos stages #7 to #17; Urodele embryos stages #11 to #30. 

 For heteroplastic transplantations, use: 



Rana: catesbiana, palustris, pipiens, and sylvatica. 

 Amblystoma: punctatum and tigrinum. 



Technical: Standard operating equipment. 



METHOD: 



Precautions : 



1. It is important that the student become thoroughly acquainted with the normal 

 development of the eye. This may be accomplished by dissecting living and 

 preserved embryos at the stages listed above. 



2. The usual precautions must be observed for operations (see section on 

 "Wound Healing"). 



3. The optimum temperature at which to rear the operated embryos differs for 

 the Anura and Urodela. For the Anura the range is 18 C. to 23°C. and for 

 the Urodela it is about 12 C. to 18°C. , depending upon the species. 



Control : For the excision, cauterizing, transplantation, and regeneration experi- 

 ments the controls will be different. In many instances the untouched (bilateral) 

 side may be considered as the control. 



Procedure : 



PRELIMINARY STUDIES ON THE EYE FIELD 



It is necessary to give here a brief description of the topography of the eye-forming ma- 

 terials. This is made possible largely by the work of Vogt (1929) in his classical paper 

 on vital staining and mapping of anlagen, from Woerdeman (1929), Manchot (1929), Pe- 

 tersen (1923) and Fischel (1921). 



Schema of the topographical relations of the eye anlagen ('Augenplatten') in the early neural plate of an 

 axolotl egg. (Copied from Woerdeman, 1929. ) 



Schema of a young urodelan neurula: the cross-hatched territory represents the material for the optic ves- 

 icles, optic stalks, and the recessus opticus, the broken line outlines the territory which the same material 

 will occupy in the stage when the neural folds have elevated. (Copied from Manchot, 1929. ) 

 Schema of the topography of the optic anlage, according to Peterson, 1923. 

 Schema of the topography of the optic anlagen, according to Fischel, 1921. 

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



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