He. Pearson et al., MICROGLIAL INVASION AND ACTIVATION IN RESPONSE TO NATURALLY-OCCURRINGNEURONAL DEGENERATION IN THE GANGLION-CELL LAYER OF THE POSTNATAL CATRETINA, Developmental brain research, 76(2), 1993, pp. 249-255
Retinae of kittens between postnatal (P) days 2 and 10 were examined f
or the presence of degenerating neuronal profiles, normal nucleoli and
microglia. Comparison of the numbers of degenerating profiles with nu
mbers of axons lost from the optic nerve suggest that the majority of
these profiles result from the degeneration of retinal ganglion cells.
Analysis of local densities of the different profiles revealed differ
ent rates of cell loss, occurring at different times in central and pe
ripheral retina. The period of rapid cell loss occurred between P2 and
P3 in central retina compared to between P8 and P10 in peripheral ret
ina. At both locations, these periods of rapid cell loss were accompan
ied by a decrease in the ratio of microglia to dying cells even though
the absolute densities of microglia increased. However, calculation o
f the clearance times of cellular debris indicate that the speed of re
moval of degeneration products is greater during rapid cell loss, whic
h suggests that cellular degeneration serves to activate the phagocyti
c process.