Placodal sensory ganglia coordinate the formation of the cranial visceral motor pathway.
The parasympathetic reflex circuit is controlled by three basic neurons. In the vertebrate head, the sensory, and pre- and postganglionic neurons that comprise each circuit have stereotypic positions along the anteroposterior (AP) axis, suggesting that the circuit arises from a common developmental plan. Here, we show that precursors of the VIIth circuit are initially aligned along the AP axis, where the placode-derived sensory neurons provide a critical "guidepost" through which preganglionic axons and their neural crest-derived postganglionic targets navigate before reaching their distant target sites. In the absence of the placodal sensory ganglion, preganglionic axons terminate and the neural crest fated for postganglionic neurons undergo apoptosis at the site normally occupied by the placodal sensory ganglion. The stereotypic organization of the parasympathetic cranial sensory-motor circuit thus emerges from the initial alignment of its precursors along the AP axis, with the placodal sensory ganglion coordinating the formation of the motor pathway.
Neurosciences Institute and Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249, USA.
Masumi
M
Takano-Maruyama
Yiju
Y
Chen
Gary O
GO
Gaufo
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D001921:Brain / Q000196:embryology / Q000502:physiology*; D001934:Branchial Region / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics; D003391:Cranial Nerves / Q000196:embryology / Q000378:metabolism / Q000502:physiology; D004525:Efferent Pathways / Q000196:embryology* / Q000378:metabolism; D004622:Embryo, Mammalian; D017950:Ganglia, Sensory / Q000196:embryology / Q000378:metabolism / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009432:Neural Crest / Q000378:metabolism / Q000502:physiology; D055757:SOXE Transcription Factors / Q000235:genetics / Q000378:metabolism; D017833:Visceral Afferents / Q000196:embryology* / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D055757:SOXE Transcription Factors; C101121:HOXB1 homeodomain protein; C080331:Hoxa3 protein, mouse; C102938:Neurog2 protein, mouse; C527924:Sox10 protein, mouse