Fig. 4.

Flh and Tbx2b do not regulate one another's expression. All panels are dorsal views of the epithalamus at the stage indicated. (A,B) tbx2b and (C,D) flh are expressed in the pineal complex anlage at the 6-somite and 24-hr stages. E,F: Double labeling for tbx2b (blue) and flh (red) reveals that they overlap in expression at the 6-somite and 24-hr stages; flh is expressed further medially than tbx2b at the 6-somite stage. G: In flh mutants, expression of tbx2b initiates on time and (H) is maintained, albeit in a reduced number of cells. I,J: In fby mutants (a lesion in tbx2b), expression of flh is unaltered relative to WT. Scale bars = 25 μm.