X-IRRADIATION STUDIES ON THE MAMMALIAN RETINA 



547 





1 ^e" « t> 



9p« 





|lV 



Fig. 3. Top: Normal \ isual cell layers of a control retina. Bottom: Retinal section 

 showin£( rod defeneration. 



Effects on the Electroretinogram 



The most significant features of the x-irradiation effect were revealed by 

 the electroretinogram ( ERG i (Fig. 4), a "mass-response" of the retina 

 to diftiise light stimulation. The ERG is recorded by an electrode 

 in contact with the cornea or the fluid oi the anterior eye chamber. It 

 depends in form and amplitude on the various parameters of light stimula- 

 tion and on the state of retinal adaptation. Its origin is still a matter of 

 dispute. It does not simply compoimd the actixities of all the elements of the 

 retinal pathway. It does not record the excitation of the retinal ganglion 

 cells but may contain components which depend on the function of the 

 second nemon, the bipolar cell. However, its greatest dependence is on the 

 first neuron of the pathway, the visual cell. 



During exposure to x-radiation. an ERG of a rather simple form was 



