Fig. 21.     A: Color micrograph illustrating ChAT labeled cell body in the medial septum approximated by PHA-L labeled terminal varicosities (arrows) following a PHA-L injection in the medial hypothalamus (case M078). B: Several PHA-L labeled terminal varicosities (arrows) from a PHA-L labeled axon are seen in close proximity to a distal cholinergic dendrite in the substantia innominata following a PHA-L injection in the lateral hypothalamus (case L125). C: PHA-L labeled terminal varicosities are seen abutting proximal dendrites (arrows) of two ChAT labeled neurons in the substantia innominata following a tracer injection in the lateral hypothalamus (case L123). The terminal varicosities shown are from the same axon (arrowhead). D: PHA-L labeled terminal varicosities in proximity to a proximal dendrite of ChAT labeled cell in the dorsal HDB from case L123. The grid simulates the proportions of the ocular reticle used to screen sections from high magnification light microscopic analysis. Scale bar (A-D): 16 μm (one division of grid in D). E-G: Composite maps illustrating putative zones of contact between afferent fibers and cholinergic neuronal elements following PHA-L injections into the (E) far-lateral hypothalamus (case L125), (F) mid-lateral hypothalamus (case L123), and (G) medial hypothalamus (case M067). These maps were composed from 8 camera lucida drawings which were aligned and superimposed to generate the final figure. Cholinergic neurons are represented by black dots. Zones of putative contacts between cholinergic elements and PHA-L labeled terminals are depicted as red squares (corresponding to 80x80 µm areas in the section).