Extended Data Figure 3. Serial sectioning through the anterior quarter of a 5.5 dpf larval zebrafish.

a, Overview micrographs from a collection of 17,963 × ~60 nm-thick transverse serial sections that span 1.09 mm through a 5.5 dpf larval zebrafish. Embedding the larval zebrafish (green dashed circle) in support tissue stabilized sectioning. Dashed lines indicate cropping. b, Volume rendering of aligned overview micrographs. Magenta and yellow planes correspond to reslice planes in c. Green plane corresponds to section outlined in a. c, Reslice planes through an aligned overview image volume reveal structures contained within the series and illustrate the sectioning plane relative to the horizontal (upper) and sagittal (lower) body planes. This series spans from myotome 7 through the anterior larval zebrafish, encompassing part of the spinal cord and the entire brain. Dashed lines indicate where reslice planes intersect. d, Histograms of lost, partial (missing any larval zebrafish tissue), or adjacent (lost-partial or partial-partial) events per bin of 50 sections. In total, 244 (1.34%) sections were lost and 283 (1.55%) were partial for this series. No two adjacent sections were lost. Inset histograms expand the shaded regions to provide a detailed view of sectioning reliability with bin sizes of 5 sections. Dashed lines indicate the number of lost sections if uniformly distributed throughout the series. Scale box: b, 250×250×250 µm³. Scale bars: a,c, 250 µm.