title: RXR gamma gene is expressed by discrete cell columns within the alar plate of the brainstem of the chicken embryo.
abstract: With in situ hybridization assays, we mapped the distribution of retinoid X receptor gamma (RXR gamma) gene transcripts in the central nervous system of the chicken embryo. Previous studies have demonstrated the presence of RXR gamma transcripts in migrating neural crest and in neural crest derivatives throughout the peripheral nervous system, implicating RXR gamma as an early pan-neural crest marker (Rowe et al. 1991. Development 111:771-778), and in the retina (Hoover et al. 1998. J Comp Neurol 391:204-213). Here we report the presence of RXR gamma transcripts in discrete regions of the developing neural tube, within the hindbrain, the cerebellar plate, the optic tectum, and the diencephalon. At stage 10, when migrating neural crest expresses RXR gamma transcripts, we detect no transcripts in the neural tube. By stage 13, RXR gamma transcripts accumulate to detectable levels along the midline of the posterior optic tectum, where the neural crest-derived sensory neurons of the mesencephalic trigeminal nucleus are located. By stage 15, RXR gamma transcripts also appear in an intermittent longitudinal cell column within the mantle zone of the alar plate of the hindbrain, eventually extending into the cerebellar plate rostrally and into the cervical spinal cord caudally, with a gap at about rhombomere 3. By stage 19, transcripts appear in a discrete population of cells within the diencephalon. Expression in these cell populations continues until at least stage 22.5, when many neuron populations have been generated in the hindbrain. The localization of the RXR gamma-positive cells to the mantle zone suggests that they are postmitotic and are probably neurons. Their specific alar locations indicate that they reside within sensory columns and potential downstream targets, evidently corresponding to some of the central components of the trigeminal system.
authors.affiliation: Department of Physiology, University of Oslo, Norway.
authors.forename: F
authors.initials: F
authors.lastname: Hoover
authors.forename: A
authors.initials: A
authors.lastname: Kielland
authors.forename: J C
authors.initials: JC
authors.lastname: Glover
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000196:embryology*; D002490:Central Nervous System / Q000196:embryology; D002642:Chick Embryo; D015870:Gene Expression; D009474:Neurons / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics* / Q000378:metabolism; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014276:Trigeminal Nerve / Q000196:embryology
chemical_list: D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors