passages.id: split_1_test_241_passage
passages.type: progene_text
passages.text: In the present study , we showed by Northern analysis and in situ hybridization that Smoothened ( Smo ) , a key component in hedgehog signal transduction , was expressed in chondrocytes in both adult mice and mouse embryos at 16 days post - coitum in vivo , suggesting that Ihh directly acts on chondrocytes .