Actin filament organization within dendrites and dendritic spines during development.

The myosin S-1 subfragment was used to label actin filaments in the developing rat brain. The results show actin filaments present throughout the dendritic region with highest concentrations within growth cones and regions of spine development. Between 6 and 25 days postnatal, spines became more complex and actin filaments within them increased in number and formed a complex network. The observed organization of actin supports the hypothesis that actin has a role in the protrusion of spines from the dendrite during development.