Differential expression of RAR-ß and RXR-γ transcripts in cultured cranial neural crest cells

In situ hybridization reveals that RAR-β and RXR-γ genes in mesencephalic neural crest cultures are independently regulated. RAR-β transcripts are found in all cells, with a slight increase in signal/cell with time in culture. In contrast, the distribution of RXR-γ transcript is initially uniform but becomes increasingly heterogeneous, so that after 72 h in culture, a significant proportion of cells lack transcripts while a small subpopulation contains very high levels of message. These differences in the behaviour of the RARβ and RXRγ genes in vitro can be related to differences in their expression patterns in vivo.