Comparative study of afferent connections in the habenula in rats and cats after injection of horseradish peroxidase

: The habenular complex of 11 cats and 13 rats was injected with horse Radish peroxydase (HRP) (30% solution, 0,05--0,4 microliter). Retrograde labelling of cells was visualized after a survival period of 24 to 48 hours by means of the method of Lavail et al. (1973). The resultats obtained with this method suggest significant species differences regarding the habenular afferents in cats and rats. One of the most striking differences is that the entopeduncular nucleus of the cat contains very few HRP labelled cells after lateral habenular nucleus injection in comparison to the entopeduncular nucleus of the rat which can be shown to be the major source of afferents to the lateral habenular nucleus by the same method.