Figure 3. Spatial Segregation of V1 Interneuron Subpopulations.

(A) V1 interneurons in p0 L3-L5 segments of En1.nLacZ mice. D/V axis range: 132 to −265 μm; M/L axis range: 127 to 487 μm, 5th-95th percentiles from central canal. Contours represent density at the 30^th-90^th percentiles.

(B) Spatial clustering of V1^Pou6f2/Nr5a2 interneurons (blue, F_a = 0.236) (p < 0.00001, one-tailed Monte Carlo test compared to parental V1).

(C) M/L biases in distributions of V1^Sp8 (X_epicenter = 162 μm) and V1^Pou6f2 (X_epi = 403 μm) interneurons. p < 1 × 10⁻²⁰, Wilcoxon Rank Sum test in x-axis, V1^Sp8 or V1^Pou6f2 vs V1^Parental, and V1^Sp8 vs V1^Pou6f2.

(D) D/V biases in distributions of V1^Pou6f2 (Y_epi = 66 μm), V1^FoxP4 (Y_epi = −158 μm), and V1^MafA (Y_epi = −277 μm) interneurons. V1^Sp8 interneurons (Y_epi = 72 μm) also occupy a dorsal position. p < 1 × 10⁻²⁰, Wilcoxon Rank Sum test in y-axis for V1^Pou6f2, V1^FoxP4, V1^MafA, or V1^Sp8 vs V1^Parental.

E) Subdivision of V1^Pou6f2 interneurons into medial (Nr5a2⁺, blue) and lateral (Lmo3⁺, red) subsets in p0 L3-L4 spinal segments.

(F) V1^Prdm8 interneurons fractionate into dorsal Sp8⁺ (blue) and ventral FoxP4⁺ (red) composite groups.

(G) V1, V1^Pou6f2, and V1^Sp8 settling position at L3 (blue) or L5 (red) in p0 mice. p < 0.0001 for L3 vs L5, 2D KS test.

(H) Constancy of x,y position (mean ± SD) for V1 interneurons expressing Sp8 (n = 7), Pou6f2/Nr5a2 (n = 8), Pou6f2/Lmo3 (n = 4), FoxP4 (n = 7), Nr3b2/Nr5a2 (n = 8), Nr3b3/Prox1 (n = 6), and MafA (n = 7 animals).

(I) Spatial distributions of seven V1 subsets. Contours represent 60^th-90^th percentile densities. See also Figures S3 and S4, and Table S1.