Figure 1: Microglia initiate filopodia formation in developing somatosensory cortex.
From: Microglia contact induces synapse formation in developing somatosensory cortex
(a) Fluorescent image of P10 somatosensory cortex showing the distribution of L2/3 neurons (tdTomato, red) and microglia (EGFP, green), Scale bar, 50 μm. (b) Time-lapse in vivo images showing dendritic filopodia formation following microglia contact (white arrow indicates contact point, red represents dendrites, green represents microglia). Scale bar, 2 μm. (c) Histogram showing the distribution of latencies of filopodia formation following microglia contact (n=12 filopodia from 5 animals, bin size=1 min). (d) Filopodia formation rate at microglia contact points (contact) and at dendritic regions 10 and 20 μm adjacent to the contact point. ‘No contact’ represents the entire dendrite, excluding the contact point (one-way ANOVA, post-hoc Bonfferoni test, error bars are mean ±s.e.m.; exact P-value is P=0.0000002; n=8 animals). (e) Survival rate of filopodia formed following microglia contact (black line) or formed without prior microglia contact (grey line) (two-way ANOVA, post-hoc Bonfferoni test, error bars are mean ±s.e.; exact P-value is P=0.11; n=25 dendrites from 9 animals). (f) Comparison of filopodia formation rates in dendrites at microglia contact points (contact) and at dendritic locations 10 μm adjacent to the contact points (10 μm) in three different age groups. Microglial contact-induced filopodia decreases over postnatal development (paired t-test, error bars are mean ±s.e.m.; exact P-values are P=0.0003 (P8–P10), P=0.37 (P12–P14), P=0.41 (P26–P30); P8–P10: n=8 animals, P12–P14: n=7 animals, P26–P30: n=6 animals).
