MELANOPHORES DURING METAMOUPHOSTS I N TRITURUS TOROSUS M. C. NIT' AXD V. c'. TTTITTT S [ a n f u On itrr-sif y EIGHTLEA' FIGURES
Two well defined types of melanophores arc present in the skin of urodele larvae. The dermal rnelanophores, so desipnated because of their association with the deeper laycr of the integument, are characterized by their large size, aiid flattened, stellate form. They are the first to differentiate cluririg embryonic development, arid generally remain dominant throughout larrul life. The epiderrnal rnelanophores, by coinparison, are small in sine ancl spidery in forni, aiid remain relatively inconspicuous even after they have begun to emerge iii substantial nnmhers. Their abundance in the skin varies considerably with the species. 111 Triturus torosus, the form 011 which tlie present study is based, they are very sparsel>represented, especiall? on the trunk and tail, until late in larval life, and contribute very little to the distincti\Te pigmentary appearance of the tadpole. With the approacli arid onset of metamorpliosis, however, they begin to appear in large numbers, with the result that the entire hack and sidci assume a unif orin brown coloration. Coiicui-rently, the dermal melanophores map be obserred to undergo esteririve fragnientation and degeneration, and ereiitually most of the original coinpleineiit disappears.
Althougli it is impossihle to follow directly tlie fate of all of the pigmentary content thus 1-eleased, observations shon
The investigakion was aided by grants from the Committee on Gionth of the National Research Coumcil, ancl the Rockcfellcr Fountlation.