Hypothalamic projection to the lateral septum in the guinea pig an HRP study

In the guinea-pig, a bilateral projection from the magnocellular dorsal nucleus (MDN) of the hypothalamus and the lateral hypothalamus (LH) to the lateral septum nucleus (LSN) was demonstrated by using horseradish peroxidase (HRP) histochemistry. The deposition of crystalline HRP into the LSN consistently resulted in labeling of cell bodies within the limits of the MDN. Labeled perikarya exhibited a typical granular appearance. The better labeling was obtained with HRP implants located in the posterior LSN. As it was previously described that most of the MDN cells were enkephalin-containing and that the posterior LSN contained enkephalinergic nerve terminals, it is suggested that the MDN may contribute to the enkephalinergic innervation of the LSN. In addition a group of labeled neurons was found in the LH. They were located ventrally and laterally in relation to the fornix column. HRP reaction product filled these neurons in a Golgi-like manner, providing information about their morphology.