Nature - USA (2020-01-23)

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nature research | reporting summary

October 2018

For a reference copy of the document with all sections, see nature.com/documents/nr-reporting-summary-flat.pdf

Life sciences study design

All studies must disclose on these points even when the disclosure is negative.

Sample size The sample size of scRNA-seq and ATAC-seq were determined by availability of human tissues. We collected 7 hippocampus from embryonic

stages for scRNA-seq with 2 samples at the same developmental stage as replications. Final dataset scale was determined according to the

quality control criteria as described in the methods. 6 mice were used per time point to quantify the phenotype.

Data exclusions Cells detected with less than 800 genes were removed as low quality cells. Genes which only expressed in fewer than 30 cells (0.1% of total

cell number) were excluded as recommended by Seurat (Ver.2.3.4 ).

Replication As scRNA-seq, 2 biological replicates in GW22 and no replicates for other time points. 3 replicates were used in ATAT-seq experiments. 6 mice

were used per time point to quantify the phenotype as described in figure legends. All replications were consistent for data results.

Randomization The samples were allocated into each experimental groups based on the gestational stage. See methods 'Tissue sample collection and

dissection'.

Blinding The investigators were blinded to group allocation during data collection and analysis.

Reporting for specific materials, systems and methods

We require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material,

system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.

Materials & experimental systems

n/a Involved in the study

Antibodies

Eukaryotic cell lines

Palaeontology

Animals and other organisms

Human research participants

Clinical data

Methods

n/a Involved in the study

ChIP-seq

Flow cytometry

MRI-based neuroimaging

Antibodies

Antibodies used For immunostaining, the following antibodies to the following proteins were used:

Mouse monoclonal [MEM-28] to CD45 ,Abcam,ab8216, GR302332-1;

Rabbit polyclonal to NEUROD2,Abcam,ab104430,GR94291-4;

Rabbit Polyclonal to PAX6,BioLegend,901301,B201255;

Goat polyclonal to SOX2,Santa Cruz,sc-17320,H1406;

Mouse monoclonal to NEUROD1, Abcam,ab60704,GR3183945-2;

Rabbit monoclonal [EPR18114] to HMGA2, Abcam, ab207301;

Rabbit polyclonal to HOPX, Santa Cruz, sc-30216, D1615;

Mouse monoclonal [B56] to Ki67, BD Biosciences, 550609, 19679;

Rabbit monoclonal [EPR19273] to PROX1, Abcam, ab199359, GR45436-1;

Rabbit polyclonal to OLIG2, Millipore, ab9610,3018858 ;

Human monoclonal [IGX3421] to Myelin Basic Protein, Abcam, ab209328,GR278417-4;

Mouse monoclonal [GA5] to GFAP,CST,3670S,6.

Validation All antibodies were validated by the supplier for human or mouse samples and by comparing to the manufacturer's or in-house

results.

Animals and other organisms

Policy information about studies involving animals; ARRIVE guidelines recommended for reporting animal research

Laboratory animals CD1 mouse, female, timed pregnant at E13.5.

Wild animals This study did not involved the wild animals.

Field-collected samples This study did not involved the samples collected from the field.