358
Z. R Y C H T E R
Ectopia could be constantly produced by ablation of part of the
ventral pericardial wall. The underlying part of the heart loop (e.g., the
atrium) protruded through the pericardial defect and determined the
direction of the heart axis and position of the ectopic heart (e.g.,
suprasternal, sternal with the apex tending toward the right or left side,
etc.) (Rychter and Lemez, 1959c). A small pericardial defect at the
summit of the heart loop caused only a herniation of the ventricular
wall.
In some cases, the sternal ridges growing together prevented the
development of the non-protruding atrium and caused its hypoplasia,
which entailed a series of interesting changes in the cardiovascular
system which will be analysed in the next part.
C. Haemodynamic Effects of Suppressing Development of the Atrium and
their Morphogenetic Significance
The developing right or left atrium was suppressed by means of a
large clip on the 4th day of incubation (Fig. 27a, a') (Rychter and
Lemez, 1958a, b, 1959c, 1960b). The result of intervention was much
more pronounced in the case of the left atrium than of the right: the
FIG. 27. Development of the heart and of great vessels after the suppression of the
right (a d) or left (a'-d') atrium on the 4th day of incubation. Vdx, Vsin = right, left
heart ventricle. Other abbreviations as in Fig. 26.
Z. R Y C H T E R
Ectopia could be constantly produced by ablation of part of the
ventral pericardial wall. The underlying part of the heart loop (e.g., the
atrium) protruded through the pericardial defect and determined the
direction of the heart axis and position of the ectopic heart (e.g.,
suprasternal, sternal with the apex tending toward the right or left side,
etc.) (Rychter and Lemez, 1959c). A small pericardial defect at the
summit of the heart loop caused only a herniation of the ventricular
wall.
In some cases, the sternal ridges growing together prevented the
development of the non-protruding atrium and caused its hypoplasia,
which entailed a series of interesting changes in the cardiovascular
system which will be analysed in the next part.
C. Haemodynamic Effects of Suppressing Development of the Atrium and
their Morphogenetic Significance
The developing right or left atrium was suppressed by means of a
large clip on the 4th day of incubation (Fig. 27a, a') (Rychter and
Lemez, 1958a, b, 1959c, 1960b). The result of intervention was much
more pronounced in the case of the left atrium than of the right: the
FIG. 27. Development of the heart and of great vessels after the suppression of the
right (a d) or left (a'-d') atrium on the 4th day of incubation. Vdx, Vsin = right, left
heart ventricle. Other abbreviations as in Fig. 26.