114 2 OCTOBER 2020•VOL 370 ISSUE 6512 sciencemag.org SCIENCE
Fig. 1. Neural progenitor cells exhibit homotypic preference.Green, magenta,
and blue represent p3, pMN, and p0 cells, respectively. (A) Cross section of
an 11-somite–stage neural tube, stained with in situ HCR probes againstnkx2.2a
(green),olig2(red), anddbx1b(blue). Scale bar, 20mm. (B) Average intensity
profiles ofnkx2.2a,olig2, anddbx1balong the V-D axis of the spinal cord, showing
good agreement between the fluorescent reporters (dashed lines) and in situ HCR
(solid lines). Error bars indicate SEM. (C) Illustration of the dual pipette aspiration
assay. F, force (of adhesion or pull). Scale bar, 10mm. (D) The adhesion force
measured from six doublet types. The boxes represent 25th, 50th, and 75th
percentiles of the data. *P< 0.05; **P< 0.01; ***P< 0.001 (Student’sttest).
(E) Illustration of the triplet assay. Scale bar, 10mm. (F) Triplet assay results
showing homotypic preference. *P< 0.05; **P< 0.01 (binomial test).Fig. 2. A combinatorial adhesion code composed ofcdh2,cdh11, and
pcdh19.(A) Confocal cross section of a neural tube from a 10-somite–stage
embryo withTgBAC(cdh2:cdh2-mCherry);Tg(actb2:membrane-citrine). Scale bar,
20 mm. (B,D, andF) V-D intensity profile ofcdh2-Cherry (B), normalized to
the membrane citrine signal and V-D intensity profiles ofolig2andcdh11
(D) ornkx2.2aandpcdh19(F) based on in situ HCR. Shaded regions of green,
magenta, and blue are identical to Fig. 1B, representing the positions of the
p3, pMN, and p0 domains, respectively. Gray lines represent the average
profiles from individual embryos. Error bars indicate SEM. (C,E, andG) Cross
sections of 10-somite–stage embryos after in situ HCR staining againstolig2
andcdh11(C),nkx2.2aandpcdh19(E), andolig2andpcdh19(G). Scale bars,
20 mm. (H) Adhesion code summary. Circled areas represent the relative
abundance of each adhesion molecule, quantified from the normalizedcdh2-
Cherry level (B) or the in situ HCR signals forcdh11(D) andpcdh19(F).RESEARCH | REPORTS