comparative studies on brain gangliosides of about 80 species belonging to all classes of vertebrates reveal : a : distinct increases in concentration with phylogenetical progress of nervous organization , b ) decreases in number of single fractions , c ) changes in the polarity ( degree of sialylation , n- or o-acetylation of sialic acids ) , d ) alterations in the preponderance of one of the three possible pathways of biosynthesis .
C0006104
brain
C0086045
concentration