Experimental strategy. (A) Dissection of the ventral lateral midbrain (VLM) region. (i) In situ sagital view of a HH st16 electroporated embryo expressing pCAβ-IRES-Dmrt5 construct (dorsal view in the inset). Red lines indicate the midbrain (Mb) region, which was dissected out. (ii-iv) Coronal sections of midbrain. White lines mark the VLM region. This region was isolated from (ii) control embryos (VLM), (iii) VLM exposed to current (VLMi), (iv) VLM exposed to current + GFP (VLMg), and VLM exposed to current + Dmrt5 (VLMd; image not shown) for investigation of transcriptional profiles by microarray analysis. (B) Tissue processing and microarray analysis. Six VLM tissues were pooled for each biological replicate, and three biological replicates were used for each condition. cDNA was isolated from these pools and hybridised to the Affymetrix Chicken Genome Array. Following MAS5, normalisation and filtering, genes whose expression differed significantly between the wild type (WT; VLM) and VLMi, VLMg and VLMd were identified by one-way ANOVA.