A quantitative comparison of the efficiency of orthograde axonal transport and transsynaptic transport of iodinated (125I) wheat germ agglutinin (I-WGA) and horseradish peroxidase labeled I-WGA (I-WGA-HRP) in the rat visual system.

A quantitative study of the orthograde axonal transport of iodinated wheat germ agglutinin (I-WGA) and I-WGA conjugated to horseradish peroxidase (I-WGA-HRP) demonstrated labeling of both the lateral geniculate nucleus and the visual cortex following intraocular injections. I-WGA was 13 times more efficient than I-WGA-HRP as a marker of the primary projection from the retina to the geniculate and 3 times more efficient than I-WGA-HRP as a marker of the second order projection to the cortex.