TERATOLOGY 41:737-742 (1990)
Ectopia Cordis in the Chick Embryo Heart: An Experimental Study OSCAR C. JAFFEE AND ANDREW L. JAFFEE Department of Biology, University of Dayton, Dayton, Ohio 45409 (A.L.J., O.C.J.); Department of Zoology, Hebrew University, Jerusalem, Israel (O.C.J.)
ABSTRACT Ectopia cordis was observed during a study on the effects of a calcium antagonist (verapamil) on chicken embryo heart development. Experimental procedures, carried out a t 60 hours of incubation, included placement of windows in eggs, injection of verapamil or saline, and the removal of ovalbumen from eggs. Fluid removal caused a downward displacement of the embryo and helped separate the embryo and its membranes from the shell membranes. Ectopia cordis was only observed in experiments involving fluid removal. One exception, the appearance of one ectopic heart in a window-only experiment (no fluid removed), remains unexplained. The movements of fluids, brought about by the withdrawal of ovalbumen from eggs, and the subsequent effects of such movements on the positioning of embryos seemed to be the most important factor in the genesis of ectopia cordis. Also observed in fluid removal experiments were asymmetric circulations, abnormal embryonic flexion, and several embryos whose positions were rotated. These abnormalities were probably related to fluid removal and/or ectopia cordis. Ectopia cordis, a rare form of congenital heart disease, is distinguished by a complete or partial protrusion of the heart outside of the thorax. Literature on the cause of this defect is not abundant. Kaplan et al. ('85) reviewed a number of cases of ectopia cordis. They postulated the involvement of extraembryonic membranes in the development of this condition. But the etiology of ectopia cordis remains unknown (Bergsma, '79; Dahl et al., '81). The available literature on ectopia cordis consists mainly of reports of spontaneously appearing cases. Freeman and McGovern ('84) described a case in a piglet. Kummerfeld et al. ('83) found this condition in a newly hatched pigeon. A spontaneously appearing ectopic heart was discovered in the authors' laboratory (unpublished). Ectopic hearts have also been observed in cattle, dogs, and guinea pigs. The authors have been unable to find any published studies in which this defect was produced experimentally. In a study of the effects of a calcium antagonist (verapamil) on chicken embryo heart development, the authors found that
0 1990 WILEY-LISS, INC.
their experimental procedures led to the consistent appearance of ectopia cordis. Since this was not previously reported in experimental studies, it was decided to continue the study with the aim of analyzing mechanisms involved in the genesis of this rare condition. MATERIALS AND METHODS
Verapamil, in pure powder form, was supplied by the Searle Company. Fertile, White Leghorn chicken eggs were obtained from the Department of Poultry Science of the Ohio State University for the first phase of the study. For the second phase, they were obtained from the flock at the Hebrew University in Jerusalem, Israel. In order to allow application of test substances into eggs and directly to the extraembryonic membranes at an early stage (Hamilton-Hamburger stage 17) (HamReceived January 17, 1989; accepted October 31, 1989. Oscar C. Jaffee's present address is 1823 Harvard Boulevard, Dayton, OH 45406. A preliminaryreport was presented at the lOlst Annual Meeting of the American Association of Anatomists.
738
O.C. JAFFEE AND A.L. JAFFEE
TABLE 1 . Summary of the results Procedure Series 1 Fluid removaliverapamiliwindow Fluid removalisalineiwindow Control Fluid removal-only Window-only Control Series 2 Fluid removaliverapamiliwindow Fluid removaliwindow Control ‘NS
=
of Series 1 and Series 2 experiments Survival rate, Ectopia cordis, survivorsitotal ectoDiasisurvivors (%)
Sienificance
19/26 34137 31/37 16/28 17/20 44/50
8/19(42) 5/34( 15) 0131 3/16(18) 1/17(6) 0144
P =
Ectopia Cordis in the Chick Embryo Heart: An Experimental Study OSCAR C. JAFFEE AND ANDREW L. JAFFEE Department of Biology, University of Dayton, Dayton, Ohio 45409 (A.L.J., O.C.J.); Department of Zoology, Hebrew University, Jerusalem, Israel (O.C.J.)
ABSTRACT Ectopia cordis was observed during a study on the effects of a calcium antagonist (verapamil) on chicken embryo heart development. Experimental procedures, carried out a t 60 hours of incubation, included placement of windows in eggs, injection of verapamil or saline, and the removal of ovalbumen from eggs. Fluid removal caused a downward displacement of the embryo and helped separate the embryo and its membranes from the shell membranes. Ectopia cordis was only observed in experiments involving fluid removal. One exception, the appearance of one ectopic heart in a window-only experiment (no fluid removed), remains unexplained. The movements of fluids, brought about by the withdrawal of ovalbumen from eggs, and the subsequent effects of such movements on the positioning of embryos seemed to be the most important factor in the genesis of ectopia cordis. Also observed in fluid removal experiments were asymmetric circulations, abnormal embryonic flexion, and several embryos whose positions were rotated. These abnormalities were probably related to fluid removal and/or ectopia cordis. Ectopia cordis, a rare form of congenital heart disease, is distinguished by a complete or partial protrusion of the heart outside of the thorax. Literature on the cause of this defect is not abundant. Kaplan et al. ('85) reviewed a number of cases of ectopia cordis. They postulated the involvement of extraembryonic membranes in the development of this condition. But the etiology of ectopia cordis remains unknown (Bergsma, '79; Dahl et al., '81). The available literature on ectopia cordis consists mainly of reports of spontaneously appearing cases. Freeman and McGovern ('84) described a case in a piglet. Kummerfeld et al. ('83) found this condition in a newly hatched pigeon. A spontaneously appearing ectopic heart was discovered in the authors' laboratory (unpublished). Ectopic hearts have also been observed in cattle, dogs, and guinea pigs. The authors have been unable to find any published studies in which this defect was produced experimentally. In a study of the effects of a calcium antagonist (verapamil) on chicken embryo heart development, the authors found that
0 1990 WILEY-LISS, INC.
their experimental procedures led to the consistent appearance of ectopia cordis. Since this was not previously reported in experimental studies, it was decided to continue the study with the aim of analyzing mechanisms involved in the genesis of this rare condition. MATERIALS AND METHODS
Verapamil, in pure powder form, was supplied by the Searle Company. Fertile, White Leghorn chicken eggs were obtained from the Department of Poultry Science of the Ohio State University for the first phase of the study. For the second phase, they were obtained from the flock at the Hebrew University in Jerusalem, Israel. In order to allow application of test substances into eggs and directly to the extraembryonic membranes at an early stage (Hamilton-Hamburger stage 17) (HamReceived January 17, 1989; accepted October 31, 1989. Oscar C. Jaffee's present address is 1823 Harvard Boulevard, Dayton, OH 45406. A preliminaryreport was presented at the lOlst Annual Meeting of the American Association of Anatomists.
738
O.C. JAFFEE AND A.L. JAFFEE
TABLE 1 . Summary of the results Procedure Series 1 Fluid removaliverapamiliwindow Fluid removalisalineiwindow Control Fluid removal-only Window-only Control Series 2 Fluid removaliverapamiliwindow Fluid removaliwindow Control ‘NS
=
of Series 1 and Series 2 experiments Survival rate, Ectopia cordis, survivorsitotal ectoDiasisurvivors (%)
Sienificance
19/26 34137 31/37 16/28 17/20 44/50
8/19(42) 5/34( 15) 0131 3/16(18) 1/17(6) 0144
P =
