BERRY— HINSEY: RECOVERY, REGENERATING NERVES 569 



in the experiments on the tibial, peroneal, and saphenous nerves, and 

 about 80% recovery of normal fiber diameter was found at 365 days. 



.5 3.5 6.5 9.5 .5 



FIBER DIAMETER 



I I I I I I I I I I I I 



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IN MICRA 



Figure 7. The top row of fiber distribution graphs is from dista! stumps, after simple suture of 

 the hypoglossal nei-\-e; bottom row, from the distal stump, when the central end of the hypo- 

 glossal was sutured to the cervical .sympathetic trunk. 



The time allowed for regeneration in both the top and bottom rows is indicated in days. 

 (Modified from Hammond & Hinsey.") 



With the diameter studies of the hypoglossal-to-hypoglossal series 

 as a basis for comparison, the suture of the hypoglossal nerve to the 

 cervical sympathetic trunk produced remarkably different results. 

 The lower row of histograms in figure 7 shows the fiber distributions in 

 the distal stumps (cervical sympathetic), at the same intervals of 

 regeneration as those in the upper row of hypoglossal-to-hypoglossal 

 experiments. At 216 days, the histogram of the distal segment shown 

 in the lower row was not much different than that of the distal segment 

 in the upper row. However, at 250, 300, and 365 days, the fibers did 

 not continue to grow as in the simple hypoglossal-to-hypoglossal suture, 

 but, instead, the diameters decreased. By 365 days, the distal segment 

 of the hypoglossal-to-cervical sympathetic cross-suture took on the 

 diameter characteristics of the normal cervical sympathetic trunk, in- 

 stead of the hypoglossal nerve. 



The converse experiments, those of cross-suturing the cervical sym- 

 pathetic trunk into the hypoglossal nerve, were carried out to find out 

 if the larger Schwann tubes of the distal segment would allow the re- 



