A temporal sequence of rhombic lip derivatives express Lhx9 , Tbr1 or Pax6 . A. Cumulatively labelled cells at st.31/E7 following electroporation of green fluorescent protein (GFP) into the r1 rhombic lip (arrow) at st.16/E3. B. Electroporation (arrows) at successively later stages (st.22-st.28) labels progressively fewer populations (①②③④) at st.31 (stage of electroporation indicated top right): *indicates only a residual population. C. Lhx9 expression in a st.31/E7 embryo electroporated with GFP at st.16/E3. D. GFP (above) and overlay with Lhx9 expression (below). E. Serial coronal sections through an embryo at st.31/E7 electroporated with GFP at st.23/E4 (left) with higher magnification view of GFP (middle) and Lhx9 (right) in the most ventral cells (①). F. Tbr1 expression in a st.31/E7 embryo electroporated with GFP at st.26/E5. G. GFP (above) and overlay with Tbr1 expression (below). H. Serial coronal sections through an embryo at st.31/E7 electroporated with GFP at st.23/E4 (left) with higher magnification view of GFP (middle) and Tbr1 (right) in the medial cerebellar nucleus (②). I. Pax6 expression in the medial cerebellar nucleus (③ white arrow) and EGL (④ white arrow) in a flat-mounted E6 brain. J. Pax6 labels only EGL (white arrow) at E8, shown in sagittal Section. K. Lhx9 (red) and Tbr1 (blue) highlighting gap (white arrow) between expression domains where cells of the lateral cerebellar nucleus reside. L. Summary of periods of neurogenesis and gene expression in rhombic lip derived populations: ventral nuclei ①; lateral cerebellar nucleus CbN(l) ②; medial cerebellar nucleus CbN(m) ③; external granule layer (EGL) ④. m, medial; l, lateral. Scale bars: 200 μm in A-B and E-H, 500 μm in C-D, F-G, I-J and K.