Left ventricular unloading during reperfusion.

1543 it before publication.' We have recently become aware of a published thesis by Margot M. Bartelings8 at the University of Leiden that discusses cardiac development and uses the new terminology of Pexieder et a17 as well as the classic nomenclature. Although we are in general satisfied with this suggested nomenclature,7 we believe it would benefit from clarification on two points. For our own study, we used embryos that fall into the category of late "early organogenesis" or early "advanced organo-genesis." We think that the demarcation between the two periods is ill defined. This is made even more confusing because the term "heart loop stage" is equated with "early organogenesis" when there is an "absence of any specific internal features." We consider our hearts to be at the "heart loop stage" based on van Mierop's terminology2; however, they have a wealth of internal features. It would be helpful if Pexieder et a17 clarified this distinction by avoiding the use of previously existing vocabulary and adopting the use of stages of development for the vertebrates most commonly encountered in studies of heart development to delineate the periods of organogenesis. This would leave no doubt regarding the transition. Our second suggestion regarding the new nomenclature involves the outflow tract, an area of particular interest to us. We assume that the terms "ventriculoarterial portion" and "arterial portion" refer to the region we designated the conotruncus and aortic sac.1 These embryonic structures contribute to the adult infundibulum and aortic vestibule, semilunar valves, and proximal portions of the aorta and pulmonary trunk. We suggest that this area be called the "outflow tract" rather than "ventriculoarterial portion" and "ar-terial portion," terms that are tongue-twisters and still make the mistake of dividing the area into two regions. We have very comfortably adopted the term "outflow tract" at Dr. Thompson's suggestion and have found that it is almost never an advantage to divide it into two regions.9 If for some reason the outflow tract needs to be divided, perhaps the portion covered by the myocar-dial sheath9 could be designated "proximal outflow tract," and the portion between this cuff and the aortic arch arteries could be designated "distal outflow tract." With the exception of the outflow tract, we intend to adopt the terminology of Pexieder et a17 and urge other cardiac embryolo-gists to do the same.photography of the developing heart in neural crest-ablated chick embryos. The article by Van …