A histochemical and ultrastructural study of vascular innervation in selected human and animal tissues

Abstract

A review of the factors regulating peripheral blood flow is presented and the importance of the autonomic nervous system discussed. The purpose of this project was to extend the animal studies on vascular innervation to human tissues and in this way attempt to determine some of the constraints operating in the control of blood flow in particular vascular beds. A number of techniques designed to identify autonomic subpopulations were employed. Adrenergic nerves were demonstrated by the formaldehyde-induced fluorescence and glyoxylic acid fluorescence techniques, whilst possible cholinergic nerves were shown by acetylcholinesterase staining. The electron microsoope was also used to aid identification of autonomic subpopulations through an examination of vesicle populations in nerve endings. Extensive ultrastructural studies were undertaken on non- lactating human breast and no periarteriolar axon profiles were observed. Ultra-violet fluorescence microscopy and acetylcholinesterase staining also gave negative results indicating that blood flow through the non-lactating human breast is not controlled by autonomic nerves supplying the vessels. Studies on lactating rat mammary gland revealed a rich periarteriolar adrenergic innervation and the possibility remains that such an innervation may be present in the human gland when lactating. No acetylcholinesterase stained fibres were observed around the vessels but the arteriolar walls themselves stained strongly. Human axillary lymph nodes were examined in the electron microscope and periarteriolar adrenergic nerves demonstrated.