Differentiation of apical and basal dendrites in pyramidal cells and granule cells in dissociated hippocampal cultures.

You Kure Wu,Kazuto Fujishima,Mineko Kengaku,Makoto Sato

doi:10.1371/journal.pone.0118482

Abstract

Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s) from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.

Highlights

Neurons of the central nervous system exhibit enormously diverse dendritic arbor architecture, which determines both the number and type of synaptic inputs received, and critically affect neuronal connectivity
The apical and basal dendrites are oriented in opposite directions and occupy different layers, with apical dendrites extending toward the hippocampal fissure through the stratum radiatum and stratum lacunosum-moleculare, and basal dendrites extending in the opposite direction through the stratum oriens
Morphologies of neurons in the primary culture of the mouse hippocampal formation The primary culture of hippocampal neurons was prepared from the hippocampal formation of neonatal mice at postnatal day 0 (P0)

Summary

Introduction

Neurons of the central nervous system exhibit enormously diverse dendritic arbor architecture, which determines both the number and type of synaptic inputs received, and critically affect neuronal connectivity. Differentiation of Dendrites in Pyramidal and Granule Cells hippocampal formation, exhibiting distinct dendritic arbor structures. Pyramidal cells give rise to a long, thick apical dendrite and several minor basal dendrites that emerge from the apex and base of the teardrop-shaped soma, respectively. The dendritic architecture of pyramidal cells take a biconical shape and are able to receive synaptic inputs from different afferent sources. In contrast to pyramidal cells, dentate granule cells have a monoconical arbor of apical dendrites with all branches directed toward the superficial region of the molecular layer. Immature granule cells produce transient dendrites from the basal portion of the soma, which are retracted by adulthood, except for in a small population of granule cells in primates [1,2,3]

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