Figure 1.

D-type cyclins display discrete domains of expression in the developing spinal cord.(a,b) In situ analysis of CyclinD1 (a) and D2 (b) expression on cross-sections of the neural tube of 3- to 3.5-day-old chicken neural tube. (c,d) Co-detection of the transcripts CyclinD1 or D2 (dark blue) with the protein Nkx2.2 (brown). (e-h) In situ hybridization performed on serial sections showing CyclinD1 (e), Olig2 in combination with anti-BrdU immunostaining (f), CyclinD2 (g), and Irx3 (h). Note that both CyclinD1 and D2 are present in the dorsal aspect of the ventricular zone (a,b). A small dorsal domain expresses CyclinD1 at a lower level (a, asterisk). In the ventral part of the spinal cord, distinct domains (1, 2, 3) of ventral progenitors express distinct CyclinDs, the pMN domain expressing mainly CyclinD1. Transcripts encoding CyclinD1 seem more homogenously distributed along the apico-basal axis than those encoding CyclinD2, which are reinforced on the basal side (b).