[Demonstration of a 2d LH-RH neurosecretory system in the duck hypothalamus]

Using immunocytochemical techniques with an anti-LH-RH immuneserum, evidence of two neuronal systems secreting LH-RH has been shown in the Duck hypothalamus. In addition to the previously described system, located in the preoptic nucleus, a second system could be demonstrated in the infundibular nucleus. The perikarya of the infundibular LH-RH producing neurons were significantly smaller than those of the preoptic neurons. On the other hand, under the experimental conditions used, the infundibular system had approximately five times less LH-RH secreting neurons than the preoptic system, and its perikarya appeared less heavily loaded in IR LH-RH. The LH-RH containing axons from both neuronal populations ran down to the external layer of the median eminence, where they ended in close contact with the capillaries of the hypophysial portal system.