Objective: The epicardiac neural ganglia of the adult human heart are distributed in the seven neural ganglionated subplexuses. The aim of the present investigation was to determine the distribution of the epicardiac ganglia in human fetuses of different age, because intrinsic cardiac nervous system of the human fetus has not been enough investigated so far.
Material and methods: In the present study seventeen human fetus hearts were investigated, in which epicardiac neural ganglionated plexus was visualized by histochemical method for acetylcholinesterase.
Results: Analysis of the total hearts preparations showed that: (1) the epicardiac neural ganglionated plexus of the fetus at fifteen weeks of gestation has already differentiated into seven ganglionated subplexuses, structure of which is typical for the adult human heart; (2) the epicardiac plexus of fetuses at 15-40 weeks of gestation contains on average 865+/-40 epicardiac ganglia, that may widely range in number from 644 to 1193; (3) the largest number of the neural ganglia is concentrated on the posterior surface of both atria, where up to 76% of all ganglia maybe located; (4) the difference between the number of epicardiac ganglia in the human fetuses at the early (15-25 weeks) and late (26-40 weeks) stages of fetogenesis is not statistically significant (p>0.05). In conclusion, both the distribution and the number of the epicardiac ganglia of fetuses ranging from 15 to 40 weeks of gestation are not age-dependent but varied substantially from heart to heart.