Numerical estimations of structures in the cochlear nuclei and cochlear afferents and efferents

The cochlear nuclei and the cochlear afferents and efferents have been studied by light and electronmicroscopy. Numerical estimations have been performed concerning number of neurons and fibre population. Ultrastructural elements such as myelin lamellae, neurofilaments and neurotubuli were counted and measurements of axonal diameter and circumference performed. The results, seen in conjunction with other morphological and neurophysiological data indicate that it may be realistic to speak about two auditory nervous systems: one innervating the outer hair cells and one innervating the inner hair cells.