File:Normal Neuronal Migration into the Olfactory Bulb Compared to Kallmann's Syndrome.jpg

Olfactory Neuronal Migration in Kallmann's Syndrome

In a normal individual (left), the olfactory neurons (ON) embedded in the olfactory epithelium have axons which migrate through the cribriform plate (CP) during development to reach the olfactory bulb ^[1]. The ONs synapse with mitral cell (M) dendrites in the olfactory bulb's glomerular layer (GL). The axons arising from the mitral cell bodies (pink squares) form the olfactory tract (OT). In the developing foetus, neurons secreting gonadotropin-releasing hormone (GnRH, shown in green) begin in the olfactory placode and migrate along the olfactory nerves towards the forebrain ^[1].

In a foetus with X-linked Kallmann's Syndrome (right), the olfactory axons do not reach the olfactory bulb ^[2]. Similarly, GnRH neurons do not complete migration to the forebrain, instead, they remain in the dura mater layers on the dorsal aspect of the cribriform plate^[2].

References

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