Extended Data Fig. 2: Role of the vomeronasal pathway in mounting behaviour.

a, Mounting time for males with a sham surgery (sham) or the VNO removed (VNOX) towards LPS females (sham, n = 5 and VNOX, n = 7; from 2 independent experiments). b–d, Virus encoding the anterograde trans-synaptic tracer (AAV₁-hSyn-Cre) was targeted to the AOB in Ai14 reporter mice that express tdTomato in a Cre-dependent manner (b). Representative images (c) and quantification (d) of trans-synaptically labelled tdTomato⁺ neurons in BST, MEA and COApm at the specified anterior-posterior axis (n = 4; from 3 independent experiments). Scale bars, 500 μm. e–g, Virus encoding ChR2 (AAV₂-hSyn-hChR2-eYFP) was targeted to the AOB (e, f). g, Representative image of FOS expression in the COApm upon photoactivation of the AOB, from n = 3 mice. Scale bars, 500 μm. h, These data are associated with Fig. 1g. Number of FOS-expressing neurons in the vomeronasal pathway after interaction with PBS or LPS females. **P < 0.01, ***P < 0.001 and ****P < 0.0001 calculated by unpaired two-tailed t-test (a), one-way ANOVA with Bonferroni’s post hoc test (d) and two-way ANOVA with Sidak’s post hoc test (h). Graph indicates mean ± s.e.m. P values are described in the Supplementary Statistical Information.