Age related changes in neuron number in the tegmental nuclei of Gudden of the mouse.

The number of neurons was estimated in the ventral part of the dorsal tegmental nucleus and in the ventral tegmental nucleus of Gudden in brains of male ASH/TO strain mice aged 6, 15, 25, 28 and 31 months. In both nuclei there was a significant decrease in neuron number after 28 months of age. The possible significance of these results was considered in relation to the connection of Gudden's tegmental nuclei with the mammillary nuclei in which neuron number is stable with age, and with the vestibulocerebellar system which loses neurons with age.