Fig. 3

WT hippocampal neurons display morphological spine deficits when grown in the presence of an Fmr1 KO astrocyte feeder layer. a Schematic illustrating the indirect astrocyte-neuron co-culture set-up. Astrocytes were grown in a cell culture insert with a permeable membrane facing the neurons and sharing the same, defined medium. b Cumulative frequency distribution of spine lengths comparing WT neurons grown independently and in co-culture with WT or Fmr1 KO astrocyte feeder layers (AFL) at 17 DIV. c WT hippocampal neurons grown without direct contact with Fmr1 KO astrocytes present with longer spines. d Assessment of spine morphology in Fmr1 KO AFL/WT neuron co-cultures indicates a significant increase in the density of filopodia-like spines and (e) a decreased density of stubby spines. Spine density represents the average number of spines scored in a 10 μm dendritic segment. f Fmr1 KO AFL/WT neuron co-cultures exhibit a reduction in the number of co-localized synaptic puncta relative to WT neurons cultured alone or with a WT AFL (p < 0.01). Excitatory synapses represent the average number of co-localized puncta scored in a 50 μm dendritic segment. One-way ANOVA with Bonferroni correction was used to analyze the data. Data are presented as the mean ± SEM, **p < 0.01, ***p < 0.001; n = 50 neurons per group, N = 2 independent experiments