Origin of the afferent connections to the parolfactory lobe in quail shown by retrograde labelling with a fluorescent neuron tracer.

Unilateral injection of Fast Blue retrograde fluorescent neuron tracer into the parolfactory lobe (POL) in the quail showed multiple innervation of this structure. Neurons projecting into the POL were located in three areas: the telencephalon, where they were scattered in the paleostriatum, the archistriatum and ventral hyperstriatum, and among the fibers of different tracts including the anterior commissure, the occipito-mesencephalic tract and the fasciculus prosencephali lateralis; the diencephalon, where fluorescent neurons with large multipolar perikarya were found in the dorsal thalamic wall; the midbrain, where large perikarya were located in the ventralis area of Tsai, the locus coeruleus, the nucleus subcoeruleus, around the medial longitudinal fasciculus, in the substantia grisea centralis, the formatio reticularis mesencephali and among the fibers of the brachium conjunctivum. In most cases, axons innervating the POL ran parallel to the fibers of the medial forebrain bundle and contralateral to the perikarya from which they originated. This study also showed that the anterior and posterior parts of the POL received fibres from different sources.