The rate of spreading and proliferation of avian utricular epithelia on fibronectin (FN) is maintained at similar levels throughout life. A) Rates of spreading shown as fold increase in area throughout the culture period were similar in neonates (postnatal day 0 (P0), n=41 sheets) and adult chickens (P60, n= 45 and P180, n= 44). B) Inhibition of cell division with the DNA polymerase inhibitor aphidicolin (25 μM) yielded a similar degree of tissue spreading in utricular epithelial sheets from P0 (n=9 sheets) and P180 (n=5 sheets) chickens at 24, 48 and 72 hr in culture. C) S-phase entry after 72 h in culture shown as the percentage of BrDU positive cells was maintained at similar levels in chickens ranging in age from P0 to P420 (number of epithelia sheets analyzed; P0, n=27; P6, n=27; P12, n=26; P24, n=23; P60, n= 24; P180, n=27; P420, n= 11). CBT and SPAFAS are the names of the two different suppliers of chickens utilized in this experiment.