[The ultrastructural level of different peptidergic nerve endings in the median eminence, dorsal hypothalamus and septum].

Comparison at the ultrastructural level of nerve endings containing 6 different peptides (LH-RH, C terminal ACTH, somatostatin, enkephalin, CRF, hp GRF) using immunocytochemical means has been performed. The results show that the granules are in each case very similar in size and appearance. This aspect can therefore be used to individualize the neuropeptide terminals but it does not permit to determine the nature of the peptide. In the central nervous system many different neuropeptide terminals have been observed at the ultrastructural level but in the majority of cases neither the role nor the pericarya of origin could be precised. On the contrary for the enkephalin containing nerve endings observed in the lateral septum it has been possible to prove that pericarya of origin were located in the hypothalamus and more precisely in the magnocellular dorsal nucleus.