Figure 4

Olivary pretectal nucleus innervation and onset of pupillary light responses. (A) The olivary pretectal nucleus (OPN) is innervated by CTB-labeled RGC axons at P0 and ipsilateral and contralateral axons have segregated by P7. (B) Melanopsin^Cre/+;Z/AP-labeled axons show a similar innervation pattern from birth. (C) In contrast, Melanopsin^tauLacZ/+-labeled axons are not detected until P7 and show adult-like innervation of the OPN shell by P14. (D,E) The paradigm used for all pupil measurements (D) and representative images (E). Note that the pupil appears white at P7 because at this early time point it was necessary to reflect infrared light off the back of the eye to make the iris visible to the camera. Carbachol was used to induce maximal constriction of the ciliary muscle. (F) Percent constriction of pupil was measured and the summary of data for PLR is shown. Significant light responses are detected from P7 onward (n = 3 or more mice per time point, one-way ANOVA with Tukey post hoc test, error bars are mean ± standard error of the mean). No baseline constriction was observed in adult mice. Scale bars: 100 μm (A-C).