Morphological analysis of developmental changes in pontine noradrenergic neuronal groups in the neonatal rat.

We examined the morphological changes in two pontine noradrenergic neuronal groups, area A5 and the locus coeruleus (LC), in neonatal Sprague-Dawley rats between postnatal day 1 and day 10. The volume of the unilateral LC exhibited no significant developmental change. Meanwhile, the number of A5 neurones counted unilaterally was significantly larger on days 1-2 than on days 3-4 or day 10.