passages.id: split_4_test_3413_passage
passages.type: progene_text
passages.text: Inhibiting the caudal - related genes cdx1a and cdx4 in zebrafish embryos caused ectopic expression of genes that are normally expressed in the posterior hindbrain and anterior spinal cord , and ectopic formation of the hindbrain motor and commissure neurons in the posteriormost neural tissue .