I am a 5th year PhD student, investigating the development of the arterial pole in the zebrafish heart. Because fish have gills rather than lungs, they do not acquire a secondary (pulmonary) circulation and therefore have a relatively simple heart with a single ventricle and a single atrium. Blood enters these myocardial heart chambers through the sinus venosus and exits through a smooth muscle structure called the bulbus arteriosus. In simple terms, I define the arterial pole of the zebrafish heart as the junction of the ventricle with the bulbus arteriosus and the bulbus itself. We have demonstrated that there is evolutionary conservation in aspects of arterial pole development and that the bulbus is akin the arterial trunk(s) of vertebrates possessing a four chambered heart. We have also provided evidence for the presence of a conotruncus in the zebrafish (a distinct collar of myocardium surrounding and just distal to the ventriculoarterial valve). I am currently attempting to construct fate maps of the pre-gastrulation embryo and the neural crest to ascertain the origin of this region of the heart. In addition, I am investigating arterial pole development in the Van gogh mutant (vgo), which lacks the transcription factor Tbx1 and has a seriously truncated bulbus. Thus, because Tbx1 is implicated in correct neural crest cell function, we hypothesize that the bulbus relies on neural crest cells for normal development and may in fact be neural crest-derived.