autoradiograms of monkeys sacrificed at various short intervals following exposure to a pulse of 3h-thymidine showed that ipn neurons were generated in the proximity of the ventricular surface near the confluence of the 3rd ventricle and cerebral aqueduct , migrated ventrally along the midline and then spread laterally after reaching the ventral midbrain , where ipn was first recognized at e45 ( stage 23 ) .
C0007769
cerebral aqueduct
C0025462
midbrain