The intracardiac neurones of the fetal human heart in culture.

Dissociated cell culture preparations were employed to study intracardiac neurones of the atria from human fetal hearts at 9 to 21 weeks' gestation. Intracardiac neurones were not observed in cultures dissociated from the ventricles. Single neurones, as well as groups, could be identified by phase-contrast microscopy in all of the atrial cultures prepared from 14 to 21 weeks' gestation, and protein gene product 9.5-like immunoreactive neurones were detected in cultures from as early as 10 weeks' gestation. The neurones were mononucleate, with a prominent nucleolus or multiple nucleoli, and often had extensive neurites. Neurones tended to be bigger in cultures from later stages in gestation, and these cells appeared to be more mature with a complex pattern of neurite outgrowth. Many neurones from 15 to 20 weeks' gestation expressed somatostatin-like immunoreactivity in culture. A very low proportion of cultured neurones was immunoreactive for neuropeptide Y and its C-terminal flanking peptide. Neuropeptide Y-like immunoreactive neurones also contained 5-hydroxy-tryptamine-like immunoreactivity in culture, but dopamine beta-hydroxylase-like immunoreactive neurones were not detected. This study is the first description of human intracardiac neurones in culture and forms the essential baseline for further direct investigation of these cells.