Figure 4.

Dynamic transcription factor expression during SCN prenatal maturation. Representative ISH images of Six3, Lhx1, and RORα mRNA expression in the embryonic mouse SCN (E14.5 to P0), showing spatial specificity and prenatal maturation of transcription factor expression. Dotted lines indicate margins of SCN estimated from the cell density marker DAPI (example shown in rightmost panels). White arrow at E15.5 indicates onset of visible clustering of cells. Note change in Lhx1 pattern from global to centrally restricted between E15.5 and P0. E17.5 Lhx1 image was obtained from tissue cut at a different angle and thus the appearance of larger SCN compared with Six3 and RORα. Scale bar, 250 μm.