Chronotopic organization of olfactory bulb axons in the lateral olfactory tract.

The arrangement of axons in a tract can have a specific effect on the organization of functional neuronal circuits. Here we describe olfactory bulb axons chronologically arranged in the lateral olfactory tract. Newly differentiated projection neurons over the whole olfactory bulb are similarly marked with transient expression of c-kit protein. Their axons are assembled together and project into the ventral superficial part of the tract, displacing the older axons. This special assembly of the axons explains the nontopographic relationships between the olfactory bulb and the lateral olfactory tract axons that have been described in previous studies and could possibly influence the subsequent selection of the olfactory target areas by these axons.