The early appearance of disc shedding in the rat retina.

Postnatal development of the processes of rod outer segment shedding and phagocytosis was examined in 10- to 50-day-old rats. The number of phagosomes increased gradually from a minimallevel in the second postnatal week to that of the adult at 4 weeks after birth. No differences were observed in animals raised under two different light intensities i.e., relatively bright (45 to 50 ft-cd) and very dim (0.3 to 0.5 ft-cd). A definite circadian rhythm was observed first in 15-day-old animals, indicating that this is an important internal control mechanism that is synchronized with eye opening and the initiation of visual function.