202 



NORMAL HISTOLOGY. 



increase in number and size until, at the end of the first year, they are plentiful 

 and may attain a diameter of from . 2-. 3 mm. , although usually they measure 



Lobule 



\ Interlobular septum 

 "^ / 



Blood-vessels, 

 injected 



Cortical follicl 



Cortex 



Capsule 



FIG. 250. Transverse section of lobe of thymus body of child, showing general arrangement of 



lobules. X 20. 



much less (40-60 At). These bodies, present only in the medulla, are com- 

 posed of large concentrically disposed epithelial elements, which, flattened 



Capsule 



Cortex 



srftfe'Ct 



Thymic bodies within medulla 



FIG. 251. Section of thymus, showing details of cortical and medullary substance. X 200. 



and connected with the reticulum-cells at the periphery of the corpuscle, at 

 its centre exhibit evidences of degeneration, such as nuclei poor in chromatin 

 or disappearing, breaking down of cytoplasm or invasion of the cells by 



