obtained 2 million pass filter reads per single cell (Extended Data Fig. 6c). We considered a gene expressed if there were at least 10 reads detected for that gene. Cells that expressed more than 1,000 genes and <10% mitochondrial RNAs were kept for analysis. To avoid bias during FACS from RNA contamination from the glutamatergic neurons on the hCS side of the fused hSS-hCS, we analyzed STMN2+ cells that did not express SLC17A6 or SLC17A7. To control for technical noise, we used a quantitative statistical analysis52 to detect biological variable genes and used them for further analysis. To cluster and visualize the cells, we used the t-SNE method in the computational software package Seurat53.
