BTBR mice exhibit altered cellular proliferation in the midline and ganglionic eminence at E14. E14 control (A) and BTBR (B) mice (n ≥6) were injected with EdU 30 minutes prior to sacrifice and immunolabeled for nuclear marker DAPI (white), EdU (green), phospho-histone H3 (PH3, blue), and Ki67, Pax6, or Tbr2 (red). Cell counts were performed for single, double, and triple-labelled cells, where data for all counts are shown in Additional file 2: Figure S2. Representative regions from the midline of control (C-E) and BTBR (F-H) mice demonstrate that BTBR mice have increased incorporation of EdU, particularly into Pax6-positive cells, as quantified in (Q). No difference was evident between the neocortex of control (I-K) and BTBR mice (L-N, and quantified in R). However, the ganglionic eminence of BTBR mice (P) exhibited decreased incorporation of EdU compared to control (O), and reduced mitosis as indicated by PH3 staining (quantified in S). Scale bar in B represents 500 μm for A-B. Scale bar in H and P represents 100 μm for C-H and I-P respectively. Mann-Whitney U test for significance: *P <0.05, **P <0.01. Data are presented as mean ± SEM. (E14: Embryonic day 14; EDU, 5-Ethynyl-2′-deoxyuridine; DAPI, diamidino-2-phenylindole; Pax6: Paired Box 6; Tbr2,T-Box Brain Protein 2).