C57BL/6 mice at 17.5 days of pregnancy were sacrifced and forebrains of embryos were dissected. Cell plating and culture manipulation were done as previously described [E-MEXP-878]. At day 1, day 2, day 4 and day8 of in vitro culture development, total RNA was extracted and miRNAs were profiled on Illumina Sentrix Universal-96 Array Matrix with microRNA Assay Pool designed against mirBase version 9.1.