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Background: Analysis of the innervation pattern of the thoracic duct in young and elderly human subjects has been performed. The subdivision of the vessels in cervical and lumbar region were taken in consideration., Methods and Results: Immunostaining for general nerve fibers with a PGP 9.5 marker disclosed a diffuse innervation of the thoracic duct in young subjects, which was strongly reduced in elderly subjects. In young subjects, tyrosine hydroxylase (TH) and neuropeptide Y (NPY) immunoreactive fibers, markers of noradrenergic postganglionic sympathetic fibers, were frequent; choline acetyltransferase (ChAT) immunoreactive fibers, marker of cholinergic parasympathetic nerve fibers, were also well represented. Therefore, the influence of sympathetic and parasympathetic nerve systems on the thoracic duct can be confirmed. The immunoreactivity of vasoactive intestinal peptide (VIP), a neuropeptide frequently present in cholinergic parasympathetic nerve fibers, was scarcely present. Dopamine-positive fibers were observed in few short nerve fibers. Substance P (SP)-positive fibers were widely distributed in the medial and intimal smooth muscle layers, suggesting their involvement as contractile modulating fibers and sensitive fibers. In elderly subjects, an evident reduction of all specific nerve fibers analyzed was detected, the ChAT-positive fibers being the most affected., Conclusions: The lymphatic vessel thoracic duct is able to regulate hydrodynamic lymph flow by intrinsic contraction of its smooth muscle layer. Therefore, analysis of the thoracic duct innervation pattern may be important in assessing the regulation of vessel contraction. These findings called attention to the reduction of lymphatic drainage functionality affecting fluid balance in the elderly.

The presence and distribution of acetylcholinesterase (AChE) and cholineacetyl transferase activities (Chat) were examined in the bronchus-associated lymphoid tissue (BALT) of juvenile, adult and old rats. Histoenzymatic and immunochemical methods were used in association with quantitative analysis of images and statistical analysis of the data. Our results showed that both AChE and Chat activities were primarily confined to the BALT lymphoid cells. Only a low level of activity was observed in the sub-pleural parenchyma of the lung and in the wall of the bronchus. Moreover, both AChE and Chat activities in the BALT are specifically located in the lymphoid cells. Histoenzymatic staining and corresponding values of quantitative analysis of images confirmed morphological and immunochemical results. Finally, the intensity of histoenzymatic staining for AChE and of immunochemical staining for Chat in BALT of rats strongly decreases with age. On the basis of our results we hypothesize that both AChE and Chat activities may play an important role in BALT and both these enzymes undergo specific age-related changes.

Background: In recent years anatomic research has demonstrated the presence of various types of nerve fibre in the cornea. The purpose of this study was to investigate the distribution of catecholaminergic fibres in various corneal layers and to study the effects of an experimental superficial corneal lesion on the pattern of catecholaminergic nerve fibre distribution in the various corneal layers., Methods: Three weeks after the creation of an alkali burn in the centre of the right cornea of five albino rabbits, the animals were killed, and histologic sections from the cornea of both eyes were stained for observation of catecholaminergic nerve fibres and photographed on black-and-white film. The photographs were examined using the Quantimet image analyser (Leica)., Results: Catecholaminergic nerve fibres were observed in the corneal epithelium and the deep stromal layers. Sections from injured cornea showed a drastic reduction in epithelial and superficial stromal catecholaminergic nerve fibres, whereas the nerve fibres in the endothelium and deep stroma were not damaged., Interpretation: Although catecholaminergic nerve fibres were observed in all corneal layers, the pattern of catecholaminergic fibres following the creation of a superficial lesion of the cornea seems to suggest that the superficial and deep nerve fibres may have a different distribution.

We have studied the cholinergic nerve fibers (CNF) of human uveoscleral tissue in normal and pathological conditions (intraocular pressure: (IOP) of various degrees ) and have performed a quantitative image analysis of CNF with the aim of studying an hypothetical association between IOP and the uveoscleral level of cholinergic neurotransmitter in nerve fiber of the enucleated human eyes. Eleven patients, previously enrolled in our medical protocols are affected by an increase of IOP of various degrees, were subjected to surgical enucleation of one eyeball for traumatic or neoplastic reasons and were the donors of samples of the uveoscleral tissue for CNF demonstration. The samples were also submitted to quantitative image analysis. An enzymatic activity, Acetylcholinesterase (AChe), is present in nerve fibers that innervate the human uveoscleral tissue. The AChe-positive nerve fibers represent about 7.2% of the observed area in normal conditions, while in patients with elevated IOP AChe activity is about 20.3% of the total observed area. The increase of AChe activity in our experiments, all performed under the same conditions, and therefore, with comparable results, may be related with the increase of IOP.

The innervation pattern of rat and mouse inferior vena cava was studied using catecholamine fluorescence and cholinesterase histochemical methods. Adrenergic nerve fibers innervate only abdominal portions of the inferior vena cava, while cholinergic nerves are chiefly distributed to the thoracic inferior vena cava and show a gradual decrease in the abdomen. Chemical sympathectomy performed with the neurotoxin 6-hydroxydopamine does not alter the pattern of cholinergic innervation of the inferior vena cava, suggesting the parasympathetic nature of cholinergic nerves.

The cholinergic innervation of coronary arteries and veins has been studied in the human. Structures resembling cholinergic nerve fibres are localised at the level of the extraparenchymal branches of the coronary arteries, organised in the adventitial plexus. Neither the coronary veins nor the intraparenchymal blood vessels are provided with a cholinergic innervation. Those findings are discussed.

Cholinergic innervation of the blood vessels of the female reproductive system was investigated in human by the cholinesterase method. The following results were obtained: 1. The uterine and vaginal arteries are provided with a rich cholinergic innervation. 2. The ovarian, tubaric and ovarian-uterine artery are poorly innervated. 3. The ovarian and uterine vein are not provided with a cholinergic innervation.

The cholinergic innervation of the aorta has been studied in some mammalian species. Cholinergic nerve fibers (CNF) are organized in the aorta of the rabbit, kid, lamb, and guinea pig in 2 plexuses. The plexuses of CNF consist of a superficial plexus localized in the adventitial layer and a deep one localized in the adventitial-medial transitional zone. Some CNF reach the outer layers of the media. In the aorta of the dog, mouse and rat CNF are organized in a single plexus localized in the adventitial layer. This nerve plexus is formed of CNF that for the most part are distributed to the vasa vasorum. The chemical sympathectomy don't alters the pattern of the cholinergic innervation of the aorta, indicating that stained CNF are parasympathetic in nature. The meaning of a cholinergic innervation of the aortic wall is discussed.

The cholinergic innervation of the human liver was studied. Slices (150--200 micrometer thick) of human liver and of the greater hepatic blood vessels (hepatic artery and vein, portal vein) were incubated in a solution of 6-hydroxydopamine (6-HDA) in order to obtain a selective degeneration of adrenergic nerves. Controls were prepared from samples incubated with buffer alone. The slices were cut on a cryostat into 15-20 micrometer thick sections and processed for the histochemical detection of cholinesterases. Cholinergic nerve fibres innervate the extra hepatic and the intrahepatic branches of the hepatic artery, the portal vein as well as the hepatic vein. Fewer cholinergic fibres innervate the hepatocytes and the hepatic sinusoids. The 6-HDA treatment does not seem to alter the pattern of the cholinergic innervation of the liver. The findings indicate the presence of a cholinergic parasympathetic innervation in the human liver.

The cholinergic innervation of the dura mater in the guinea pig, mouse and rat has been investigated. The dura mater is provided with a cholinergic innervation. After short incubation times (4--6 hours) we found acetylcholinesterase (AChE)-containing nerve fibers in close relationship with the main meningeal blood vessels. After longer incubation times, AChE-containing nerve fibers appear also in the meningeal tissue proper. Chemical sympathectomy, performed with the neurotoxin 6-hydroxy-dopamine, does not seem to interfere with the pattern of the dural cholinergic innervation. The findings are discussed.

The innervation pattern of parietal pericardium was studied in normal as well as chemically sympathectomized rats using the cholinesterase histochemical method. The existence of important regional variations in the distribution of cholinergic nerves within various portions of parietal pericardium studied was observed. The atria appear more richly innervated than ventricles, while the innervation of atria is characterized by the existence of thin and thick cholinergic nerve fibers not organized in plexuses and of elbow-shaped acetylcholinesterase cholinergic nerve fibers. Small blood vessels and islands of adipocytes receive a cholinergic innervation as well. The chemical sympathectomy does not alter the pattern of stained cholinergic nerve fibers. A possible afferent significance of the atrial innervation is discussed.

The cholinergic innervation of pancreatic islets was investigated in the human using operatory samples. In order to analyze the nature of stained cholinergic nerve fibers some specimens were incubated in a solution containing 6-hydroxydopamine (6-HDA) to obtain a selective degeneration of adrenergic nerves. Cholinergic nerve fibers are present in human pancreatic islets, and appear to be organized in an external peri-insular plexus. Some nerve fibers from the peri-insular plexus enter the islets and seem to innervate directly various types of endocrine insular elements. The 6-HDA treatment does not alter the distribution pattern of cholinergic nerve fibers within pancreatic islets.

Using the cholinesterase histochemical technique we investigated the innervation pattern of parietal pleura both in normal and chemically sympathectomized rats. AChE containing nerve fiber-like structures were observed within the parietal pleura. The apex, costal, and mediastinal surfaces of the pleura are poorly innervated, while the diaphragmatic pleura shows the richest innervation. In relation with thicker nerve fiber-like structures the existence of some elbow shaped AChE positive formation was observed. The chemical sympathectomy does not causes alterations in the distribution of AChE containing nerves in the pleura. The meaning of cholinergic innervation of parietal pleura is discussed.

The cholinergic innervation of extravascular portions of rat mesentery was studied in normal as well as 6-hydroxydopamine (7 OHDA) sympathectomized animals. We observed the presence of a cholinergic innervation unaltered by 6 OHDA treatment in extra-vascular portions of mesentery. Cholinergic nerve fibers coming from paravascular nerves forms loop]-like structures that innervate the mesentery proper. Also the islands of adipocytes of mesentery seem to be provided with a cholinergic innervation. The findings are discussed.