Journal of Neuroscience, Vol 5, 697-704, Copyright © 1985 by Society for Neuroscience
Development of the rat superior cervical ganglion: initial stages of synapse formation
E Rubin
Synapse formation in the rat superior cervical ganglion has been
investigated electrophysiologically and at the ultrastructural level.
Preganglionic axons first enter the superior cervical ganglion between days
12 and 13 of gestation (E12 to E13), and on E13 a postganglionic response
can be evoked by preganglionic stimulation. The susceptibility of this
response to fatigue and to blocking agents indicates that it is mediated by
cholinergic synapses. On E14, the overall strength of ganglionic
innervation arising from different spinal segments already varies in a
pattern resembling that found in maturity. However, the distribution of
synapses on individual target cells gradually changes in the prenatal
period. Transmission begins prior to the elaboration of ganglion cell
dendrites; therefore, the first contacts to form are largely axosomatic. As
dendrites appear (beginning on E14), ultrastructural evidence shows that
synaptogenesis becomes focused upon these processes. The significance of
these findings is discussed in relation to possible mechanisms for the
formation of appropriate synaptic connections.