Development of the human perihypoglossal nuclei from mid-gestation to the perinatal period: A morphological study

•Four perihypoglossal nuclei (PHN) were identified at mid-gestation.•Topographic relationships among the four nuclei were conserved until perinatal period.•Dorsal PHN was composed of the intercalated nucleus and prepositus nucleus.•Ventral PHN was composed of the nucleus of Roller and interfascicular nucleus.•Neuronal cytoarchitecture of each PHN matured rapidly by 28–30 postmenstrual weeks.