A quantitative histological study of neuroglial number in the retrofacial, facial and trigeminal motor nuclei in the ageing mouse brain.

The number of neuroglia was estimated in the retrofacial, facial and trigeminal motor nuclei of the mouse brain at 6, 25, 28 and 31 months of age. There was no statistically significant variation in neuroglial number in either the facial or trigeminal motor nuclei despite changes in neuron number. There was a decrease in the number of neuroglia in the retrofacial nucleus between 25 and 28 months which was slightly greater than the decrease in neuronal number, followed by a small increase in neuroglial number between 28 and 31 months of age. The glia-to-neuron ratio in the facial and trigeminal motor nuclei was identical (between 5 and 6) and did not vary with age. The ratio in the retrofacial nucleus was lower (between 1.6 and 0.9) and this reflects the differences in structure between the retrofacial nucleus and the other two nuclei.