As. Lamantia et al., RETINOIC ACID INDUCTION AND REGIONAL DIFFERENTIATION PREFIGURE OLFACTORY PATHWAY FORMATION IN THE MAMMALIAN FOREBRAIN, Neuron, 10(6), 1993, pp. 1035-1048
We have used an in vitro assay to identify sources of retinoic acid (R
A) and transgenic mice to identify target domains in the developing fo
rebrain. RA participates in a sequence of events that leads to the est
ablishment of the olfactory pathway. First, the lateral cranial mesode
rm activates an RA-inducible transgene in neuroepithelial cells in the
olfactory placode and the ventrolateral forebrain. Then, neurons and
neurites begin to differentiate in these two regions. Finally, olfacto
ry axons grow specifically into the ventrolateral forebrain and subseq
uently are limited to the olfactory bulb rudiment. The coordination of
these events, perhaps by common signals, implies that retinoid induct
ion and retinoid-activated region-specific transcriptional regulation
may help to define a forebrain subdivision and the peripheral neurons
that provide its primary innervation.