Unbiased estimation of the total number of nervous cells and volume of medial mammillary nucleus in humans

In this study, we demonstrate that aging does not provoke any changes in neuronal number or in the glial cells of the medial mammillary nucleus (MMN) in humans. Three age groups were used: young (age 17-35), adult (age 50-57), and aged (age 70-88). Furthermore, no age-dependent volumetric changes were observed in the MMN. All the estimations were performed with stereological methods: an optical fractionator and Cavalier's principle. The total number of neurons cells was estimated using an optical fractionator and amounted to 32 x 10(3) in the young group, 24 x 10(3) in the adult group, and 29 x 10(3) in the aged group. The number of glial cells was 164 x 10(3), 187 x 10(3), 185 x 10(3), respectively. Thus, all three age groups had a neuron/glial ratio of about 1 : 5, 1 : 8, and 1 :6, respectively. The MMN volume was estimated using the Cavalier's principle. The total volume was 6.98 mm(3) in the young group, 6.66 mm(3) in the adult group, and 6.80 mm(3) in the aged group. We have demonstrated that neither the total number of neurons and glial cells nor the volume of MMN are affected by age. (C) 1999 Elsevier Science Inc. All rights reserved.