20 
Northcutt 
cd c I 
0.30 - 0.10 
«® “ 0.60 
IGUANA 
ACh E 
Figure 5. Plot of regional distribution and relative intensity of acetylcholinesterase in the left telencephalic 
hemisphere of Iguana iguana. Intensity plotted as relative optical absorbance, cd, dorsal cortex; cl, lateral 
cortex cm, medical cortex; dvr 1, medial (auditory) zone of tbe anterior dorsal ventricular ridge; dvr,p, 
posterior division of the dorsal ventricular ridge; f, fornix; f-a,b, areas of moderate AChE density in dorsal 
and ventral components of medial cortex; g, ventral division of lateral geniculate nucleus: na, nucleus ac- 
cumbens; nlot, nucleus of the lateral olfactory tract; ot, optic tract; pg, preoptic periventricular gray; «, 
septal nuclei ; sp, nucleus sphericus ; st, striatum ; to, olfactory tubercle. 
septal nuclei. Contralateral projections are 
observed to the lateral cortex, and to the 
anterior olfactory nucleus after crossing in 
the habenular commissure and running in 
the contralateral stria medullaris system. 
The sole target of the accessory olfactory 
bulb is the ipsilateral nucleus sphericus 
(Figs. 2, 3). Nucleus sphericus is cup-shaped 
with the open end directed rostrolaterally 
and into which the accessory olfactory tract 
fibers from the accessory olfactory bulb 
terminate. The cell bodies of nucleus 
sphericus thus form the walls and bottom of 
the cup and send their long apical dendrites 
toward the center of the cup (Northcutt, 
1967). At present the efferent projections 
of the lateral cortex and nucleus sphericus 
are unknown in lizards. 
Both the main and the accessory olfactory 
bulbs and their primary targets demonstrate 
considerable variation in lizards. In arboreal 
agamids such as Calotes and Draco, the 
lateral cortex is present only as a vestige, 
and the nucleus sphericus is so reduced that 
no cup-shaped nucleus can be identified. In 
Calotes and in the iguanid Anolis, extensive 
parts of lateral cortex are reduced to a non- 
neural ependymal layer — the “pallial mem- 
brane” (Armstrong, Gamble, and Goldby, 
1953). This condition is most likely a case of 
