Fig. 1. ash1a, ngn1 and neuroD are expressed in spatially and temporally different populations of cells in the epiphysis. Lateral views of whole brains with anterior to the right, showing expression of ash1a, ngn1 and neuroD at 8-, 12-, 18- and 24-somite stages. Stage is indicated on the left and probe above. Arrows indicate the location of the epiphysis and arrowheads indicate the anterior and posterior limits of the epiphysis, which is delineated by the dashed lines (J,K). ash1a was expressed both earlier and more broadly than ngn1 in the presumptive epiphysis, whereas neuroD was expressed later than both ash1a and ngn1. npc, nucleus of the posterior commissure; t, telencephalon; d, diencephalon. Scale bar: in A, 50 µm for A-I; in J, 10 µm for J,K.