Intranucleus projection from caudal to rostral RE.A, Representative example of an injection site in caudal RE; the anterograde tracer BDA has been incorporated by neurons located in the caudal part of the nucleus. B, The injection shown in A resulted in a dense plexus of BDA-positive varicose fibers and terminal labeling in the rostral part of RE.C, High magnification of the terminal labeling in rostral RE shown in B. Arrows inB and C indicate the same blood vessel. Scale bars: A and B, 500 μm;C, 20 μm. f, Fornix; mt, mammillothalamic tract.