The tremendous complexity of the adult forebrain makes it a challenging task to elucidate how this structure forms during embryonic development. Nevertheless, we are beginning to understand how a simple epithelial sheet of ectoderm gives rise to the labyrinthine network of cells that constitutes the functional forebrain. Here, we discuss early events in forebrain development--those that lead to...

GABA neurons of the cerebral cortex and other telencephalic structures are produced in the basal forebrain and migrate to their final destinations during the embryonic period. The embryonic basal forebrain is enriched in dopamine and its receptors, creating a favorable environment for dopamine to influence GABA neuron migration. However, whether dopamine receptor activation can influence GABA n...

The bHLH (basic helix-loop-helix) transcription factor Mash1 is best known for its role in the regulation of neurogenesis. However, Mash1 is also expressed in oligodendrocyte precursors and has recently been shown to promote the generation of oligodendrocytes in cell culture, suggesting that it may regulate oligodendrogenesis as well. Here, we show that in the developing ventral forebrain, Mash...

Kallmann's syndrome is caused by the failure of olfactory axons and gonadotropin-releasing hormone (GnRH) neurons to enter the embryonic forebrain, resulting in anosmia and sterility. Sox10 mutations have been associated with Kallmann's syndrome phenotypes, but their effect on olfactory system development is unknown. We recently showed that Sox10 is expressed by neural crest-derived olfactory e...

The commissural plate forms the rostral surface of the embryonic vertebrate forebrain and provides a cellular substrate for forebrain commissural axons. We have previously reported that the Wnt receptor frizzled-3a (fzd3a) restricts the expression of the chemorepulsive guidance ligand slit2 to a discrete domain of neuroepithelial cells in the commissural plate of embryonic zebrafish. Loss of Fz...

Thyroid hormone is important for development and plasticity in the immature and adult mammalian brain. Several thyroid hormone-responsive genes are regulated during specific developmental time windows, with relatively few influenced across the lifespan. We provide novel evidence that thyroid hormone regulates expression of the key developmental morphogen sonic hedgehog (Shh), and its coreceptor...

The serotonin 5-HT(4) receptor (5-HT(4)-R) is an unusually complex G-protein coupled receptor that is likely to play important roles in brain development and that may underlie the comorbidity of central and peripheral abnormalities in some developmental disorders. We studied the expression of 5-HT(4)-Rs in the developing mouse forebrain at embryonic days 13, 15, 17, and at postnatal days 3 and ...

The previous companion paper detailed a technique which allowed embryonic retinal ganglion cell axons to grow from the anterior eye chamber across a PNS bridge, and enter the adult host forebrain. Embryonic eyes of E11, E14, E18 and E21 animals were sutured to a PNS bridge, the embryonic eye implanted into an adult host eye, and the distal end of the bridge implanted into the host forebrain. Re...

The extrinsic signaling pathways responsible for the formation and maintenance of the unique laminar organization of the forebrain germinal zones are largely unknown. In the present study, we asked whether ciliary neurotrophic factor (CNTF)/leukemia inhibitory factor (LIF)/gp130 signaling plays a role in the development of the germinal layers in the lateral ganglionic eminence. We found that CN...