Topographical and Morphological Studies of the Cardiac Ganglia in the Prenatal Rat

Abstract

The loci and morphology of cardiac ganglia in the heart of prenatal rats were investigated at days 15 (D15), 18 (D18), and 21 (D21) of gestation. Ganglion cells were estimated in serial transverse sections of the hearts and adjacent organs.
All ganglion cells were distributed above the coronary sulcus. Six to seven various sized groups of ganglion cells were located: (1) between the right superior vena cava and ascending aorta, (2) between the right pulmonary artery and trachea, (3) between the right pulmonary artery and right bronchus, (4) dorsal to the right atrium, (5) dorsal to the left atrium, (6) in the region of the dorsal interatrial groove and interatrial septum, (7) in the region including the left bronchus, right inferior pulmonary vein, and left superior vena cava. The ganglia contained small, densely stained ganglion cells, some nerve fibers, small unidentified cells and capillaries. The irregular shaped ganglion cells were characterized by large, round nuclei, thin layers of cytoplasm, and a few short processes. Ganglia from D18 were encapsulated by connective tissue, and some ganglion cells were surrounded by satellite cells. The mean nuclear diameter of cardiac ganglion cells was 4.28μm at D15, 4.76μm at D18, and 6.05μm at D21, their mean somal diameters were 5.79μm, 6.23 μm, and 7.58μm, and their mean numbers were 1994.33±102.31, 5771.65±233.72 and 6430.37± 630.64, respectively.
It is concluded from these results that cardiac ganglion cells can be found in 6 to 7 atrial regions in the prenatal rat and their size, number, and maturity increase from D15 to D21, but they migrate with the growth of the fetus.