Observations on the phrenic nerves and the ductus venosus in human embryos and fetuses

Ductus venosus shunting in the fetal venous circulation: regulatory mechanisms, diagnostic methods and medical importance

“…In 1942 Barron described the sphincter at the inlet of the DV in his short report43, while 2 years later Barclay et al identified, with cineangiography, a ridge located at the inlet of the fetal lamb DV which projected slightly into the DV lumen36. In agreement with later investigators, Barclay et al postulated that this ridge functioned as a sphincter mechanism36, 41, 44. In 1984 Coceani et al also described in histological sections a smooth muscle sphincter in fetal sheep45.…”

The human ductus venosus between 13 and 17 weeks of gestation: histological and morphometric studies

“…Some authors have suggested that these nerves may supply a presumed sphincter [9][10][11][12][13][14] , or may even form part of a nerve bundle passively following the course of the ductus venosus through the diaphragm 25,26 . However, this study has uniquely identified individual cells immunoreacting to S100 (nerve) antibody within the single-cell layer of smooth muscle of the ductus venosus.…”

Ductus venosus flow velocity waveforms in relation to fetal behavioural states

“…The presence of an autonomic nervous mechanism in the regulation of the observed behavioural state dependent blood flow velocity changes seems more likely. Descriptions of functional adrenergic nerves in the origin of the ductus venosus in fetal lambs have appeared, as well as nerves originating from the phrenic nerves in the proximal and distal parts of the human ductus venosus adventitial layer (Pearson & Sauter 1971).…”