682 



-t':'^!lil|. 3 



^ "V 5 III' iM 



Fig. 239. Amblystoma punctatum larvae; Qii sections of regenerating forelimbs, stained for alkaline 

 phosphatase (from Karczmar and Berg, '51). 



1, Normal enzyme distribution. Healing on the first day after amputation. E, Epidermal cap, + (single 

 plus); M, muscle, + (single plus); C, diaphysis and marrow of humerus, + + (double plus); H, 

 hypodermis. X 150. 



2, Dedifferentiation and first increase in enzyme activity, third day after amputation. Hypodermis 

 (//), perichondrium (P) and weakly staining muscle (M) dedifferentiating distally into + + (double 

 plus) mesenchyme. 



3, Accumulation of enzyme-rich mesenchyme: fifth day after amputation. Bm, Mesenchyme, staining 

 + + (double plus) to + + + (triple plus); C, proximal epiphysis of humerus with + + + (triple 

 plus) matrix; Ch, hyaline cartilage of shoulder joint with enzyme-free matrix; M, muscle, + (single 

 plus); H, hypodermis, + + + (triple plus). X 80. 



4, Early blastema with an apical gradient of enzyme activity, 9% days after amputation. This section 

 was incubated 20 hours beyond the optimum time, to test for the leakage of stain. The reference 



