engleski

Postnatal development of human CA1 pyramidal neurons

So far the data on the postnatal hippocampal development has been resctricted to available experimental animal models. The aim of the present study therefore was to examine the postnatal development of the human hippocampal pyramidal neurons. By using the rapid Golgi technique we analyzed tissue blocks with short postmortem intervals from the left hippocampi of five neurologically normal children (1, 3, 8 and 11 months, and 3 years of age) and two adults (19 and 50 years of age). The quantification of 10 dendritic parameters and 7 parameters related to dendritic spines of CA1 pyramidal neurons was carried out on a Neurolucida microscope/computer interface system (Microbrightfield, Inc.). The results revealed that most of the parameters progressively rise from birth to 3 years of age. At this age the total dendritic spine number reached about 97% of adult values for basal and about 150% for apical dendrites, while the total dendritic length was about 47% of adult values for basal and 99% for apical dendrites. Comparing the mean spine densities (number of spines per micrometer) for 3 year stage vs adult (0.76 vs 0.37 for apical and 0.73 vs 0.49 for basal) it can be seen that spine density declines only after 3 years of age for both apical (because of spine loss) and basal dendrites (mostly due to dendritic lengthening). We conclude that the development of human hippocampus is very protracted. This prolonged maturation of CA1 pyramidal neurons in man, which parallels with previous description for mossy cells in the human dentate gyrus (Seress and Mrzljak, 1992), indicates slow development of structural basis of human declarative memory.

development; declarative memory; human hippocampus; pyramidal neurons

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