Abstract
The origin of nerve fibers, especially LHRH neurons, which project into the organum vasculosum laminae terminalis (OVLT) was investigated in the rat by electron microscopy, consequent to electrolysis of the various areas of the hypothalamus and immunocytochemistry using anti-LHRH serum. Two days after electrolysis of the medial preoptic area, a large number of degenerated nerve fibers and terminals was observed in the OVLT. When the posterior half of the anterior hypothalamic nucleus and the posterior third of the suprach-iasmatic nucleus were electrolyzed, no degenerated nerve fibers were detected in the OVLT. In a partial electrolysis of the medial preoptic area, degenerating profiles were detected in the LHRH immunoreactive neurons.
The presence of a preoptico-terminal pathway was demonstrated and this pathway was found to contain the LHRH-containing neurons (preoptico-terminal LHRH pathway) .
Electronmicroscopically, it was suggested that the immunoreactivity of LHRH is acquired only in the early stage of degeneration.