although normally about 60 % of the neurons in the isthmo-optic nucleus degenerate between the 13th and 17th days of incubation , they can almost all be labeled by intraocular injections of horseradish peroxidase on the 12th day , indicating that the axons of virtually all the cells , including those neurone that subsequently die , reach the retina .
C0007610
nucleus
C0007634
cells