Rapid and reversible changes in cell shape and SA-gal by NAA treatment. (A) BJ cells were pretreated with 3 mM NAA for 18 days through two subcultures and, at PDL 79, inoculated cells were treated or untreated with 3 mM NAA for 2 days. At least one positive cell (stained blue/green) is deliberately included in every photograph to demonstrate the methodological adequacy of the staining. Changes in cell shape and SA-gal activity were apparent 2 days after addition or removal of NAA. (B) Starting at PDL 64, BJ cells underwent six subcultures in the presence or absence of 3 mM NAA for 54 days and were then inoculated at PDL 88 and cultivated for 16 days with or without NAA. The young-cell phenotypes depended on the presence of NAA but not on pretreatment with NAA.