To investigate the contribution of cranial neural crest cells to the developing cardiovascular system in the chick embryo, cauterization of various regions of cranial neural crest was performed. Five regions may be distinguished, each of which contributes mesenchyme to pharyngeal (branchial) arches 1 through 4 and 6. Ablation of arch 3, 4, and 6 regions resulted in a high incidence of persistent truncus arteriosus (PTA) associated with anomalies of the aortic arch. Dextroposed aorta (DPA) or anomalies of the inflow tract were found in all ablation groups. Although anomalies of the aortic arch arteries were induced in all ablation groups and were usually associated with intracardiac anomalies, those of the third and right fourth aortic arch were most frequent in the arch 4 and arch 4 + 6 groups. Anomalies of the sixth aortic arch were most frequent after extensive ablations that included the arch 6 region. We speculate that PTA is a direct result of the decreased population of mesenchymal cells derived from the arch 3 through 6 neural crest regions. DPA or anomalies of the inflow tract may be related to altered hemodynamics due to anomalies induced by neural crest ablation. Anomalies of the aortic arch arteries may be caused by either the direct or indirect process. Circulation 75, No. 1, 255-264, 1987. IT HAS BEEN SHOWN in quail-chick chimeras that the cranial neural crest supplies ectomesenchymal cells to the pharyngeal arches, which contain the aortic arch arteries.1 Moreover, cranial neural crest cells extending from the auditory placode to somite 3 migrate to the outflow tract of the heart to participate in aorticopulmonary and truncal septation in the chick embryo.2 Surgical removal of these premigratory cells results in a high incidence of conotruncal anomalies, which include persistent truncus arteriosus (PTA) and doubleoutlet right ventricle (DORV)34 in combination with hypoplasia or absence of pharyngeal pouch derivatives, i.e., thymus and parathyroid glands.5 These anomalies induced by ablation of cranial neural crest have morphologic features that resemble those of the DiGeorge syndrome in man.DiGeorge syndrome in man is associated with interrupted aortic arch type B, PTA, and tetralogy of Fal-

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Review ofpublished work concerning congenital cardiac anomalies reveals that at leastfour different structures have been described as the crista supraventricularis, in addition to the structure which in the normally formed right ventricle separates pulmonary and tricuspid valves. Possibility offurther confusion arises since at least two different structures have been described under the name 'septal band'. We suggest that this potentially confusing situation will be best resolved by reserving the term 'crista'for description of the muscle mass between inflow and outflow portions of the right ventricle when there are no additional outflow tract anomalies. We then suggest that at least three separate structures warrant description in hearts with outflow tract anomalies. The first separates the semilunar valves, the second separates a semilunar valve from an atrioventricular valve, and the third is an extensive septal trabeculation of the right ventricle. Our suggested terms for these structures are the infundibular septum, ventriculo-infundibular fold, and trabecula septomarginalis, respectively. However, we believe that such terms would be better decided and agreed upon within an internationally formulated 'Nomina Cardiologica', a terminology as yet lacking in congenital heart disease.Many of the controversies in paediatric cardiology relate not so much to differing observations as to differing interpretations of the embryological derivation of structures, and hence to usage of different names to describe these structures.

Effects of sympathomimetic amines without and with alpha and beta-adrenergic blocking agents on the heart rate and arterial and venous blood pressures in the 3-day-old chick embryo were studied. No chronotropic effect was observed. Norepinephrine caused a biphasic change in systolic and diastolic arterial pressures, the lower doses effecting a fall, and the higher doses a rise in these pressures. With phenylephrine a sharp rise in systolic, diastolic, and pulse pressures was seen. Isoproterenol caused a dramatic fall in systolic, diastolic, and pulse pressures. In the presence of phenoxybenzamine, the pressor effect of high doses of norepinephrine was reversed, the pressor effect of phenylephrine was abolished, and the hypotension with isoproterenol was enhanced. After propranolol, the hypotensive effect of low doses of norepinephrine was reversed, the pressor response to phenylephrine was unchanged, and the depressor effect of isoproterenol was abolished. These findings suggest the presence of functioning alpha- and beta-receptors in the 3-day-old chick embryo. Additionally, they suggest that the alpha-receptors develop more slowly in the chick embryo.

A six-week course in scientific writing and publishing was developed for pediatrics fellows at the University of Florida College of Medicine in 1984. It covered three areas: (1) grammar, syntax, and prose style; (2) construction of scientific papers; and (3) the submissions and review process. Increasing enrollment and the requests of course graduates led to the development of a second course, Advanced Scientific Writing; both courses are now offered annually. Class materials consist of texts in scientific writing, comprehensive syllabi, and handouts; the focus is on workshop activities, exercises, collaboration with peers, and individual consultations with the instructor. At the end of each course, participants complete detailed evaluation instruments, and the data obtained are used to modify the course's structure and content the following year.