Quantitative analysis of the retrograde reaction of motoneurons with an image analyser

The neuronal profiles of cell bodies in the facial nerve nucleus of adult rats were measured after partial peripheral nerve transsection. An image analyser was used for automatic recognition and morphometry. Based on classification of the neuronal profiles described in a previous paper, a morphometrical study was performed in order to analyse structural aspects of the retrograde reaction in quantitative terms. Beside the quantification of classical features of retrograde reaction (chromatolysis; nuclear eccentricity; increased basophilia; perikaryal, nuclear and nucleolar swelling), several reactive changes so far not recognized (karyoplasmic basophilia and granulation) were detected. These changes were interpreted as morphological correlates of regeneration in retrogradely reacting cells.