272 ORIGIN OF AMPHIBIAN PIGMENT 



Important In directing ultimate cellular differentiation. In Amblystoma punctatum there 

 la even distribution of melanophores while the llpophores are fused to give a continuous 

 sheet within the dermis. In A. tlgrlnum the melanophores are large and dark and are ar- 

 ranged In groups, as are also the llpophores. The time of melanophore appearance Is 

 species specific. In A. punctatum the first melanophores appear at stage #5^ lateral to 

 the medulla, beneath the epidermis, and by stage #56 they have reached the level of the 

 pronephros. The llpophores begin to appear at stage #28. Potential melanophores from 

 various species manifest different abilities to develop in Isolation, and even in the 

 normal environment there are melanophores which are dependent upon the presence of pig- 

 mented epideimls to produce melanin. Other derivatives of the neural crest may include 

 chromaffin tissue, mesenchyme, sheath cells, visceral cartilages, spinal ganglion (neuro- 

 blast) cells, sympathetic ganglia, and adrenal medulla. 



Twitty and Bodensteln (1959) found that pigment appears in the isolated chromatophorea 

 when cultured in Standard ( Holtfreter' s) Solution later than in peritoneal fluid, they 

 darken less rapidly, and the melanophores become more widely dispersed. The active migra- 

 tion of melahoblasts in vitro is confined to the period before the pigmentation is estab- 

 lished, in both species of Triturus studied, although migration does not preclude the 

 possibility of further melanlzation. They found, in general, that when the volume of the 

 culture medium was kept low that pigment development was the better, and small drops of 

 peritoneal fluid were the best. Xanthophores appear more frequently in cultures of 

 Amblystoma than in cultures of Triturus crests. 



Szepsenwol (19^+5) found that the eyes of larvae (Amblystoma and Eana) effect the body 

 color either by a humorsl substance (early in development) or reflexly (later In develop- 

 ment), when the nervous control of the melanophores dominates the humeral. These observa- 

 tions resulted from parabiotic union studies in which the eyes of one or both members of 

 the pair were excised, and subsequent pigment pattern studies were made. 



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Baltzer, F., 19'j-l - "Untersuchungen an chlmaren von Urodelen und ^yla. I. Die Pigmen- 



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Barden, R. B., 19*^2 - "The origin and development of the chromatophores of the amphibian 

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Collin, E. & P. Florentin, 1958 - "Absence de pigment melanique chez un trlton." Bull. 

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Detwiler, S. E., 1957 - "Observations upon the migration of neural crest cells, and upon 

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