298 



CELLS, TISSUES, AND ORGANISMS 



disruption of melanocytes in the area of amputation of the salamander 

 limb and the appearance of granules in epidermal cells; he considered, 

 then rejected, the possibility that granules from cytolysed melanocytes 

 were incorporated into the epidermis. Ide-Rozas (1936), however, 

 speaks of the epidermal cells as phagocytes of melanin granules (see 

 also Vilter, 1933). 



The activity of epidermis in gathering debris and, indeed, cells, 

 such as phagocytes, is especially striking after beryllium poisoning 

 ( Scheuing and Singer, 1957 ) . We have already pointed out that beryl- 

 lium causes a progressive destruction of tissues in a distal proximal 

 direction. Cellular fragments and pools of colloid are present every- 

 where among the dying tissues. The epidermis thickens greatly under 

 these circumstances, and massive extensions of it intrude deeply into 

 the dying tissues. These intrusions, particularly, but also other parts 

 of the epidermis, are choked with a stream of material moving out- 

 ward from the dying tissues (Figure 5); the basal layer is often so 

 disrupted that it is difficult to distinguish epidermal from other cellular 

 elements. The fragments within the epidermis range in size from scat- 

 tered melanin granules to recognizable nuclear and cytoplasmic debris. 

 In the light microscope, some of the debris appears to lie within the 

 cells. The intracellular localization of some detritus was affirmed with 



A.-^. 





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9 "^^^ 





Figure 5. Drawing of histological section 

 through distal epithelium 14 days after in- 

 fusion of 0.015 molar solution of beryl- 

 lium nitrate into an early regenerate and 

 stump amputed twelve days previously 

 (B215). Regenerate stopped and re- 

 sorbed. Note debris and phagocytes scat- 

 tered in the epithelium. Bodian silver 

 stain. Magnification: approximately 450 

 X. 



