Figure 4.

Superior View of the ICN

(A and B′) (A) Viewing the ICN distribution (neurons mapped as yellow dots) looking from the base toward the apex. The left and right distribution of all ICN neurons is discriminated by their relationship to the interatrial septum. Note that most ICN neurons visualized in (A) are not all on the base of the heart but mostly distributed at more inferior-caudal levels of the heart on both atria. (B′) To selectively view those neurons on the base of the heart we took this posterior view of the full ICN and retained only those above the cutoff point indicated by the dotted black line.

(B) Then these neurons are here observed from the superior view of the heart, showing the position of ICN neurons located within the hilum in between the aorta, superior vena cava, and pulmonary artery. (See also Video S3). Scale bars: 500 μm.