39. REGENERATION 



DEFINITION: The restitution of a lost organ in such a form that it is both structurally 

 and functionally complete. 



PURPOSE: To determine the ability of an embryo or larva to repair or replace a lost 

 part. 



MATERIALS: 

 Biological: 



Technical: 



Rana: stages #10 to #17 and 3. 5 to 4. 5 cm. tadpoles (may be used up 

 to 8 cm. ). 



Amblystoma: stages #10 to #29 and larvae with limbs, before meta- 

 morphosis. 



Triturus: stages #10 to #29 and late larvae. 



Standard operating equipment. 



Sodium sulfadiazine - 0. 5% aqueous (to prevent post-operative infection). 



METHOD: 



Precautions: 



1. Moderate precautions should be taken against bacterial contamination. Ani- 

 mals may be reared in 0. 5% sodium sulfadiazine as protection. 



2. Keep operated animals in separate containers. The Urodeles particularly 

 tend to snap at any moving object and will bite off each others tails or ap- 

 pendages. Provide adequate volume of medium and space for each speci- 

 men. 



3. After the wound is healed over all animals must be maximally fed (Enchytrea 

 for the Urodela and spinach for the Anura). 



Controls: 



1. Tail-fin controls consist of unoperated embryos of the same age and stage. 



2. Limb regeneration control consists of the limb of the opposite side. 



3. Blastema control consists of the transplantation of some other and neutral 

 area (unknown anlage) into the blastema. 



Experimental procedure: 



TAIL-FIN REGENERATION 



Using either anuran tadpoles (stage #25 or older) or urodele larvae (stage #45 or older) 

 with distinct tail fins, select as many specimens as possible of the same age and at the 

 same stage of development. If anuran tadpoles are used they may be placed in groups of 

 5 in single finger bowls containing a minimum of 25 cc. of medium. If Urodele larvae 

 are used they must be kept in separate containers such as finger bowls, Lily cups, or 

 #2 Slenders. 



The following directions are for Anuran tadpoles : 



1. Prepare 18 finger bowls, 6 each with the following solutions (50 cc. each). 



a. 10% Standard Solution (hypotonic) 



b. Standard Solution (isotonic) 



c. 200% Standard Solution (hypertonic) 



* The author acknowledges, with appreciation, the critical suggestions. of Dr. H. S. Emerson in organizing this exercise, particu- 

 larly that part relating to inductions within the blastema, and acknowledgement of suggestions from Dr. E. G. Butler is made 

 with pleasure. 



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