observation of division of individual cells in microdrops , plus autoradiographic studies using tritiated thymidine and standard cell cycle analysis techniques , reveal that hydroxyurea ( 10 mm ) reversibly arrests the normal progression of exponentially growing tetrahymena pyriformis through the initial 92 % of s-phase while not affecting cells in the terminal 8 % and in g2 and division .
C0080129
s-phase
C0007634
cells