34. TRANSPLANTATIONS 



PURPOSE: To determine the ability of various organ anlagen to adjust to and differentiate 

 within a new environment. 



MATERIALS: 



Biological : Early embryos of the various amphibia, Anura and Urodela. (See illus- 

 trations in previous section) 



Technical : Standard equipment. 



METHOD: 



Precautions : 



1. Remove and transplant only the area and the cells prescribed. This is very 

 important because the areas may vary with the age of the donor, and the var- 

 ious germ layers may have different developmental relations to the organ. 



2. Adequate excavation of the host site must be made, especially since there is 

 very rapid healing of any embryonic wound. 



3. The transplant must "take" (become firmly attached) before the host is moved 

 to a new environment, or changed to a different medium. 



4. Twitty (1937) and others, have found that the tissues of certain amphibia pro- 

 duce toxins which paralyze or kill the host (or transplant) in xenoplastic com- 

 binations. Triturus tissues are particularly potent when combined with 

 Amblystoma. Therefore, in making xenoplastic transplants one must keep 



in mind the possibility of tissue in compatibility. 



Controls : Since most of the organ anlagen that will be used are bilateral, the organ 

 of the unoperated side of the host may be considered as the control organ. 



Procedure : The following directions will be specific for each of the various organs. 

 It is recommended that the student consult the Chapter in this Manual pertaining 

 to the organ under study. 



Where natural pigmentations can be used to identify and trace a transplant (graft) 

 in the host environment one need not add any further marking. In homoplastic 

 transplants it will be necessary to pre-stain the donor tissue (graft) in Nile Blue 

 Sulphate or Neutral Red, in order to identify and follow the fate of the graft. 

 Operated embryos should be allowed to recover in #2 Stender dishes with agar 

 bases. 



LIMBS 

 (see pages 85-87 and 273) 



The forelimbs of Amblystoma punctatum (Texanum, jeffer sonianum, opacum and Triturus 

 torosus) are smaller and slower growing than those of A. tigrinum and A. mexicanum 

 (axolotl). However, the A. punctatum anlage' appear early (Stage #37) and develop digits 

 shortly thereafter (Stage #41), while the forelimb buds of the A. tigrinum do not appear 

 until about the beginning of the larval period (when the yolk is resorbed). Detwiler (1938) 

 states that the prospective limb material is determined as early as the late yolk-plug 

 stage, and Swett has shown that the two axes of the limbs are laid down consecutively. 

 (See exercise on Limb Fields. ) 



1. Remove the vitelline membranes of 10 specimens of Amblystoma (Stage #28) and place 

 them in sterile 10% Standard Solution. If necessary, narcotize the embryos in 

 1/3000 MS 222. If the transplants are to be within the same species, pre-stain the 

 donors in Nile Blue Sulphate. 



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