Quantitative histological analysis of the cerebellar nuclei in the cat. I. Numerical data on cells and on synapses

M. Palkovits, Éva Mezey, J. Hámori, J. Szentágothai

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Abstract

The tissue volume, cell number, cell density, as well as the numbers and densities of various kinds of synaptic terminals were determined in the cerebellar nuclei of adult cats by means of stereological procedures both on the light and electron microscopic levels. The total number of the cerebellar nuclear cells was found to be 4.6×104. On the basis of karyometric studies the medial and interpositus nuclei appear to contain two, the lateral nucleus probably three different neuron populations. The over-all numerical ratio between Purkinje and nuclear cells is 26:1. On the basis of simplified cytological and size criteria five different types of synaptic terminals were distinguished and counted separately. The total number of synaptic boutons was found to be 9.2×108, 62% of which (5.7×108) belong to Purkinje axons. The average number of synaptic boutons per nuclear cell is 2×104 with systematic differences in the several nuclei (medial = 27500; interpositus = 18000; lateral = 13900). The number of boutons of Purkinje cell origin is 11600 per nuclear cell, on the average. The average number of synaptic boutons per Purkinje axon is 474, which are distributed in a space of about 13.5×106 μm3. In view of the density of the nuclear cells and the metric parameters of their dendrites, the number of nuclear cells with which synapses might be established is 35. This is a direct measure for the divergence; i.e. one Purkinje axon may reach potentially 35 nuclear cells. The number on any nuclear cell of boutons that originate from the same Purkinje axon would be mathematically 13.5 as an average, but may vary excessively between 1 and around 50 boutons. From these data the probable convergence of Purkinje axons upon nuclear cells can be deduced as being numerically somewhere around 860, however, this apparently excessive value is mitigated by the Golgi observation that a single Purkinje axon may contribute to the same nuclear cell as many as 50 somatic synapses. The dendritic synapses - forming the vast majority of all contacts - are probably more evenly distributed among the great majority of the converging Purkinje axons but with correspondingly fewer individual contacts.

Original languageEnglish
Pages (from-to)189-209
Number of pages21
JournalExperimental brain research
Volume28
Issue number1-2
DOIs
Publication statusPublished - May 1 1977

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Keywords

  • Cerebellar nuclei, cat
  • Numerical connectivity
  • Quantitative histology

ASJC Scopus subject areas

  • Neuroscience(all)

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