[The connections of the mammillary complex and the hypothalamotegmental section with the stem in the lizard brain]

Hypothalamic connections with the brain stem in lizard (Ophisaurus apodus) were studied by means of local injection of HRP and WGA-HRP into the mamillary complex and massive injections into the hypothalamotegmental area. Reciprocal direct connections were shown between the mamillary complex nuclei and hypothalamotegmental structures, on the one hand, and following structures in the brain stem, on the other hand: griseum centrale, n. parabrachialis, n. lemnisci lateralis, n. raphae and reticular formation of caudal mesencephalic tegmentum, pons and medulla oblongata. It was concluded that direct reciprocal hypothalamo-brainstem connections, as a basis for autonomic-emotional and probably nociceptive and antinociceptive reactions in mammals were formed already in reptiles.