Reshuffling or inventing prosomeres: Expensive radiation or expensive neural tissue?

The target article is an elegant synthesis of the developmental and functional data and views on the evolutionary origin of the mammalian isocortex, integrating results from cell and molecular biology, experimental neuroanatomy, and chemoarchitectonic studies. Complementarily, we give here an account of two modes of isocortical evolution (prosomere reshuffling and invention) in terms of costs of radiation and neural tissue.

Combination of horseradish peroxidase and lucifer yellow staining for selective labeling of neurons at the electron microscopic level.

We have developed a new double labeling method for electron microscopy to characterize selectively two physiologically identified neurons on the same preparation. The stomatogastric nervous system of crustaceans was used to test the distinguishing staining characteristics of the two labels. Neurons were labeled on one side with horseradish peroxidase (HRP) and on the other side with Lucifer yellow (LY). After blue light irradiation of the tissue in the presence of diaminobendizine, the two labeled neurons could be easily observed and discriminated on the same section by the two different reaction products. This simple technique of double labeling is useful in experimental neuroanatomy for the detailed study of synaptic relationships.