Sonication-enhanced histochemistry of wheat germ agglutinin binding to intracellular sites of rat layer V cortical neurons and spinal motoneurons

Cellular surface carbohydrates have been studied extensively in relation to cell interactions. However, the presence of intracellular carbohydrates not associated with cell surface membranes has not been well-defined histochemically. We describe a technique for the ultrastructural localization of intracytoplasmic carbohydrates using a wheat germ agglutinin peroxidase conjugate. The ultrastructural aspects of wheat germ agglutinin (WGA) binding to intracellular structures of rat somatomotor cortex layer V neurons and spinal cord motoneurons were examined using sonication to enhance penetration of the lectin–peroxidase conjugate. In addition to the membrane-associated structures previously described by others, WGA binding was observed on neuronal nuclear chromatin, nuclear pores, ribosomes, microtubules, vesicular organelles, and to synaptic complexes, primarily in the presynaptic bouton. The results support data indicating that complex carbohydrates may be important in neuronal molecular processing.