CHANGES IN HUMAN CEREBELLUM WITH AGE 



17 



At present the external granule cells may be regarded as indif- 

 ferent cells, some of which become glia cells, while others become 

 nerve cells (Cajal). Of the nerve cells, some migrate to the in- 

 ternal granular layer, while others remain in the molecular 

 layer. 



The rate of disappearance of the external layer of cells has been 

 studied in man by Berliner ('05), and by Biach ('09). Their 

 results are shown graphically in chart 4. 



01 23456789 10 MONTHS 12 



Chart 4 The disappearance of the rows of cells from the external granule 

 layer of man. 



A Berliner 

 Vermis iBiach 



X Hemispheres] 



As will be seen by consulting the chart, Biach finds that at 

 birth there are about six rows of cells in the hemispheres, and 

 that these cells disappear by about the tenth or eleventh month. 

 In the vermis the number is smaller at birth and remains smaller 

 during the period of disappearance, with the result that the layer 

 has usually disappeared bj' the eighth or ninth month. 



Berliner has not made a distinction between the vermis and 

 the hemispheres, so his results are not exactly comparable with 

 those of Biach. They do, however, follow the same course and 

 leave no doubt as to the rate for the cerebellum as a whole. 



