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I'LAii: 1. Transformations of Schwann tells from 

 peripheral nerves of adult rats in tissue culture (niod- 

 ilietl from Weiss and Wang, 1945). All figures at iden- 

 tical magnification (X 710). Panel 1 shows the original 

 slender spindle shape of Schwann cells freshly emi- 

 grating from nerve. The picture also contains two 

 large endoneurial fibroblasts (large, oval, lightly- 

 stained nuclei ; dark, sutian-stained fat droplets in 

 cytoplasm). Panel 2 shows beginning ramification of 

 Schwann cells in plasma clot (note rod-shaped nuclei 

 and fat droplets). Panel S .shows giant multinucleate 

 "macrov)l>age" developed througli transformation and 



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coalescence of a group of Schwann cells at interphase 

 between cover glass and capillary exudate below 

 plasma clot. Panel 4 sliows extensively arborized 

 Schwann cells with polymorphic nuclei at fringe of 

 culture (note active extrusion of fat bodies). Panel 5 

 shows transformation stages from spindle type through 

 monopolar "flask" shape to spherical "monocytoid'' 

 form with sickle-shaped eccentric nucleus and distinct 

 zone of hyaline exoplasm. Panel 6 shows small mac- 

 rophages formed from Schwann cells in liquid -ireas 

 of medium. (Note mitosis in telophase indicated by 

 arrow.) 



