Adrenergic and cholinergic nerve supply in the porcine myometrium and cervix. A histochemical investigation during pregnancy and parturition.

The distribution of adrenergic and acetylcholinesterase-containing (cholinergic) nerves in the porcine myometrium and cervix was investigated neurohistochemically. In early and mid-pregnancy the number of adrenergic nerves increased from the adtubal part of the horns to corpus uteri, being more abundant in non-placental than in placental regions. No obvious difference in the distribution of cholinergic nerves was observed among the regions examined. The cervix was richest innervated by both types of nerves throughout gestation. The diameter of the adrenergic nerves decreased during pregnancy, while cholinergic nerves showed no such a decrease. In late pregnancy and at parturition the adrenergic innervation was richest at the adtubal part of the horns and in the cervix and scanty in the rest of the uterus. Adrenergic nerves were seen both in vascular and in non-vascular smooth muscle, while cholinergic nerves were mostly associated to blood vessels.