Experimental study of the development of the truncus arteriosus of the chick embryo heart. I. Time of appearance

Abstract

The time of appearance of the truncus arteriosus was studied in the chick embryo using an in ovo labeling technique. Three hundred embryos at stages 13-18 of Hamburger and Hamilton were selectively labeled at the distal end of the heart tube, using gelatine-india ink label; 122 of these embryos were reincubated and 111 of them reached stages 25-28. In these stages the final location of the label was determined. Only 95 of these embryos showed both a normal heart and a label located in it. The remaining embryos were discarded due to abnormal cardiac morphology or because the label was not found. Embryos labeled at stages 13-14 had label in the conus in 42.8% of the cases and in the boundary between the conus and the truncus arteriosus in 57.1% of the cases. Label placed at stages 15-16 was located in the conus in 6.1% of the cases, in the boundary between the conus and the truncus arteriosus in 44.8% of the cases, and in the truncus arteriosus in 48.9% of the cases. Finally, label placed at stages 17-18 was located in the boundary between the conus and the truncus arteriosus in 18.7% of the cases and in the truncus arteriosus in 81.2% of the cases. Our results permit us to conclude that the truncus arteriosus appears in the chick embryo as early as stages 15-16 of Hamburger and Hamilton (50-56 hours of incubation).

Cardiac looping in the chick embryo: A morphological review with special reference to terminological and biomechanical aspects of the looping process

“…In the first or “minimum” version, cardiac looping is also called “dextral‐” or “rightward‐looping” (DeHaan, 1965; Stalsberg, 1970; Olson and Srivastava, 1996). Dextral‐looping comprises only those morphogenetic events leading to the transformation of the originally straight heart tube into a c‐shaped bend/loop whose convexity is directed toward the right of the body (DeHaan, 1965; Stalsberg, 1970; Garcia‐Peláez and Arteaga, 1993; Icardo, 1996).…”

“…For example, the regional subdivisions of the c‐shaped loop are far away from their definitive topographical relationships to each other. The future ventricles lie cranial and to the right of the future atria, and a morphological subunit representing the anlage of the future great arteries (truncus arteriosus) usually has not appeared at this time point of development (Garcia‐Peláez and Arteaga, 1993).…”

“…Dextral‐looping is commonly said to be finished with completion of the rightward flapping/lateralization of the primitive ventricular bend at HH‐stage 12 (Garcia‐Peláez and Arteaga, 1993; de la Cruz, 1998). When comparing HH‐stage 12 hearts (Fig.…”

Histological study of the proximal and distal segments of the embryonic outflow tract and great arteries

“…Thus, we interpret our findings and those of Ya et al (1998) and Bergwerff et al (1998) to indicate that the smooth muscle cells of the wall of the proximal region of the aortic and pulmonary arteries do not arise from the transformation of cells originating from the truncal myocardial wall. Although Burke et al (1994) also reported that the truncal myocardium transforms into smooth muscle, their conclusion was based on the expression of various ECM proteins (fibronectin, laminin, and collagen I) in the chick embryo heart at stage 18HH, a stage at which the truncus was not yet present (García Peláez and Arteaga, 1993). Interestingly, Burke et al (1994) did describe that the smooth muscle myosin and collagen VI began to be expressed in the truncus at stage 30HH.…”

“…The conus begins to appear at stage 12HH (de la Cruz et al, 1977), while the truncus starts to emerge at stages 16–17HH (García Peláez and Arteaga 1993; de la Cruz and Markwald, 1998). Since these primitive cardiac segments appear progressively and are both externally covered by a myocardial sleeve, it is hard to distinguish an external boundary between them.…”