The parallel filaments, i.e. grain cellsaxons that after reaching the molecular layer and dividing themselves T-shaped, run transversely in the frontal plane, perpendicular to the brain's longitudinal axis, and pierce the flattened dendrite trees of the Purkinje cells . A parallel wire contacts with excitatory synapses 2000-4000, successively lined up, Purkinje cells. A Purkinje cell, in turn, is contacted by approx. 300,000 (three hundred thousand) different grain cells!
The parallel wires also pass through and excite the Korg, star and Golgi cells' dendrite trees