Volumetric and densitometric study in the cerebral cortex and septum of a lizard (Lacerta galloti) using the Timm method.

The Timm sulfide-silver method for the histochemical detection of heavy metals has been applied to the study of cortical and septal regions in the telencephalon of the lizard Lacerta galloti. Reacting areas are located in the anterodorsal septum, in the inner plexiform layer of the medial cortex, and in the plexiform layers of the dorsomedial and dorsal cortices. A very specific kind of axonal ending is responsible for this reactivity. Volumetric and densitometric measures have been performed in each reacting area. Usefulness of both measures as indicators of the number of labeled axonal endings projecting on a zone is discussed. Resemblance between these axonal endings and hippocampal mossy fiber boutons in mammals is suggested.