Distribution of adrenergic and cholinergic nerves in the porcine myometrium during the oestrous cycle. A histochemical investigation.

The presence and distribution of adrenergic and cholinergic (acetylcholine esterase-containing) nerves within the porcine myometrium and cervix were investigated by histochemical methods. The pig myometrium showed a scanty intrinsic innervation. The acetylcholine esterase-containing nerve fibres were mostly vasomotor, while the adrenergic ones were also seen among non-vascular smooth muscle cells. The adrenergic nerves were distributed in both muscle layers, and they were more numerous adcervically. The cholinergic nerves were more numerous in the adtubal part of the cornua and the cervix than in the rest of the uterus, and they predominated in the circularly oriented muscle. The scantiness of the intrinsic innervation of the myometrium, compared to other areas of the pig genitalia, might reflect differences in the neurogenic modulation of the contractility.