Analysis of the mouse mb1 and ma3 regulatory elements in Ciona embryos. A) Lateral view of a transgenic Ciona embryo at larva stage showing mb1 expression in the sensory vesicle and anterior nerve cord. B) This latter territory (arrow) corresponds to that of the endogenous CiHox1 gene. C) Schematic representation of mouse ma3 deleted fragments and their corresponding activity. D) Lateral view of a transgenic larva electroporated with construct ma3, showing expression in a couple of tail sensory neurons. E) Transverse gelatin section at level of the tail sensory neuron marked by ma3. F) The mouse ma3P construct shows the same expression of the ma3 construct in the tail sensory neurons.