Fig. 2. Somites elicit neuronal differentiation in CNP explants. (B-H,J,L,O-Q are tissue sections.) (A) Diagram of CNP explant in a stage 7+ embryo. (B-H) CNP explants continue to express Sox2 (B), cash4 (C), Sax1 (D) bra (E) and homogenous Delta 1 (F), but do not express NeuroM (G) or contain cells with neurofilament (NF)-positive fine processes (H). (I-L) CNP explants cultured with differentiating PSM contain isolated Delta 1-positive cells (I,J) and NeuroM-expressing cells (K,L), and this presomitic mesoderm differentiates into paraxis-expressing tissue (M) (note, NeuroM-positive cells in K,L appear at one end of the explant and are likely to be underlain by paraxis-positive cells, as seen in M). (N,O) CNP explants cultured with somites also express NeuroM and (P) contain cells with neurofilament-positive fine processes (arrowhead). (Q) cash4 is down regulated in CNP explants cultured with differentiating PSM. (R) CNP explants cultured alone express NeuroM after 48 hours in culture and (S) in some cases contain paraxis-positive cell. Scale bars, (B-H,J,L,O,P) 50 µm; (I,K,M,N,R,S) 100 µm; (Q) 100 µm.
