Cell death in the optic tectum of the developing rat

The death of cells was studied by light microscopy in the optic tectum of normal, developing rats. Normal cell death in the tectum during development has previously been described in chickens but not in a mammal. The total period of cell death was from the 20th embryonic day through the 11th postnatal day. During this period the number of dying cells was comparatively small for the first 2 days, reached a peak at birth and then decreased over the next 11 days. In comparison to the number of surviving cells the number of dead cells in each section was small. The dead cells appeared to be randomly distributed in all layers of the optic tectum.