Total RNA was isolated from E13.5 retinal tissue using miRNAeasy Micro Kit (Qiagen). PolyA RNA was prepared using NEBNext® Poly(A) mRNA Magnetic Isolation Module. Strand-specific RNA-seq libraries were prepared using the NEBNext® Ultra™ II Directional RNA Library Prep Kit for Illumina® (New England Biolabs) according to the manufacturer's instructions.