Developmental potentialities in the nonneuronal population of quail sensory ganglia.

Sensory ganglia taken from quail embryos at E4 to E7 were back-transplanted into the vagal neural crest migration pathway (i.e., at the level of somites 1 to 6) of 8- to 10-somite stage chick embryos. Three types of sensory ganglia were used: (i) proximal ganglia of cranial sensory nerves IX and X forming the jugular-superior ganglionic complex, whose neurons and nonneuronal cells both arise from the neural crest; (ii) distal ganglia of the same nerves, i.e., the petrosal and nodose ganglia in which the neurons originate from epibranchial placodes and the nonneuronal cells from the neural crest; (iii) dorsal root ganglia taken in the truncal region between the fore- and hindlimb levels. The question raised was whether cells from the graft would be able to yield the neural crest derivatives normally arising from the hindbrain and vagal crest, such as carotid body type I and II cells, enteric ganglia, Schwann cells located along the local nerves, and the nonneuronal contingent of cells in the host nodose ganglion. All the grafted cephalic ganglia provided the host with the complete array of these cell types. In contrast, grafted dorsal root ganglion cells gave rise only to carotid body type I and II cells, to the nonneuronal cells of the nodose ganglion, and to Schwann cells; the ganglion-derived cells did not invade the gut and therefore failed to contribute to the host's enteric neuronal system. Coculture on the chorioallantoic membrane of aneural chick gut directly associated with quail sensory ganglia essentially reinforced these results. These data demonstrate that the capacity of peripheral ganglia to provide enteric plexuses varies according to the level of the neuraxis from which they originate.