Fig. 2

Sparse random recombination in Ret^CreERt2 Brn3a^CKOAP mouse retinas reveals several types of monostratified RGCs. (a-c1) AP histochemical staining of retinal flat mounts from Ret^CreERt2/WT; Brn3a^CKOAP/WT (a, b, c) and Ret^CreERt2/WT; Brn3a^CKOAP/KO (a1, b1, c1) mice, injected i.p. with 4-hydroxytamoxifen (4-HT) at embryonic day 15 (E15, mother injected i.p. at 15^th day of gestation with 250 μg 4-HT, a-a1), at postnatal day 0 (P0, 5 μg 4-HT, b-b1), or at postnatal day 22 (P22, 75–100 μg 4-HT, c-c1). RGCs were imaged in retinas from Ret^CreERt2/WT; Brn3a^CKOAP/WT and Ret^CreERt2/WT; Brn3a^CKOAP/KO mice in which recombination was induced at E15 (n = 324 and 232 cells from 10 and 8 mice, derived from 5 distinct experiments/litters), P0 (n = 89 and 93 cells from 3 and 2 mice) or P22 (n = 148 and 145 cells, from 3 and 3 mice). (d-h2) Examples of most frequently encountered monostratified RGC morphologies: ONαS (d-d2), ON spiny (e-e2), ON and OFFβ (f-f2), M5 (g-g2) and Brn3aKO-specific betta (h-h2). For each cell, focal planes at the level of the cell body and axon (d, e, f, g, h), and dendritic arbor (d1, e1, f1, g1, h1) are shown in flat mount (en face) perspective. (d2, e2, f2, g2, h2) represent 3D reconstructions with en face perspective (top) and lateral projection (bottom). Axons are green, dendrites are blue. The horizontal bars on the sides of each vertical projection represent the boundaries of the IPL and are 25 μm long. (i-i1) RGC dendritic arbor parameters. (g) Inner distance (ID) and outer distance (OD), normalized to the IPL thickness, define the boundaries of dendritic arbor stratification, and are set to 0 at the GCL and 1 at the INL. (g1) Arbor area of the bounding polygon is determined from en face perspective. Measurements for monostratified RGCs are shown in Fig. 3. Scale bar in (a-c1) is 500 μm, in h1 – 25 μm