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Biomedical subjects

J R Garrett

Publications and source records attributed to J R Garrett.

At least 145 records · Page 8Linked to original sources
PubMed1977

The autonomic innervation of rabbit salivary glands studied electron microscopically after 5-hydroxydopamine administration.

In submandibular glands of rabbits both adrenergic and cholinergic axons are intimately associated with parenchymal cells of the intercalary ducts and the granular tubules, lying beneath the basement membrane and often in the space between the parenchymal cell and an associated myoepithelial cell. The submandibular acini receive a less intimate and less plentiful innervation by adrenergic and cholinergic axons which remain outside the basement membrane and are still associated with Schwann cells. Occasional axons of both adrenergic and cholinergic type occur beneath the basement membrane of submandibular striated ducts in intimate association with basal parts of the cells. In the parotid glands numerous adrenergic and cholinergic axons are found beneath the basement membrane of acini and intercalary ducts in intimate association with the cells.

Adrenergic Fibers↗
PubMed1977

Adrenergic influences on the permeability of rabbit submandibular salivary glands to blood-borne horseradish peroxidase.

Horseradish peroxidase (HRP) administered close-arterially, has been found to enter rabbit submandibular saliva elicited by parasympathetic nerve stimulation. Adrenalin, superimposed on parasympathetic nerve stimulation, increased the passage of HRP into the saliva. Use of alpha- and beta-adrenoceptor agonists, either separately or together, and use of alpha- or beta-adrenoceptor antagonists together with adrenalin indicate that both alpha- and beta-receptor stimulation is necessary for this increase in glandular permeability to occur. Histochemical assessment showed that HRP had permeated the interstitial spaces of the gland and entered the spaces between adjacent parenchymal cells. However, in unstimulated glands it had only reached the lumina of striated ducts, but after adrenalin administration, peroxidase was also observed within acinar lumina. This work indicates that the predominant pathway taken by the HRP was via intercellular spaces and it is suggested that the permeability between junctional complexes of parenchymal cells is capable of being modified in vivo.

Animals↗
PubMed1977

Effects of secretory nerve stimulation on acid phosphatase and peroxidase in submandibular saliva and acini in cats.

The effects of parasympathetic or sympathetic nerve stimulation either alone, or in combination, on the acid phosphatase-containing central acinar cells and the peroxidase-containing demilunar cells of the cat submandibular salivary gland have been investigated by histochemical and cytochemical techniques. The results obtained with these techniques were correlated with biochemical assays for both enzymes in the saliva secreted. The results indicate that, although both sets of nerves probably affect both sets of cells, the predominant secretory effect of parasympathetic stimulation is on the central cells and, conversely, the predominant secretory effect of sympathetic stimulation is on the demilunes. Sympathetic stimulation appeared also to have initiated synthesis of peroxidase in the demilunar cells, especially when it was superimposed upon parasympathetic stimulation.

Acid Phosphatase↗
PubMed1977

Supporting effects of myoepithelial cells in submandibular glands of dogs when acting against increased intraluminal pressure.

1. In dogs under chloralose-urethane anaesthesia secretion from the submandibular gland was recorded with the outflow at gland level and at heights of up to 50 cm above the gland.2. With the outflow level increased, secretion elicited by sympathetic nerve stimulation was far better maintained before than after injection of the alpha-adrenoceptor blocking agent dihydroergotamine.3. When the outflow level was raised while no secretion occurred, fluid flowed into the gland. Part of this amount was returned on lowering the outflow to gland level. This volume was assumed to have been accommodated in the distended luminal system, whereas some fluid was obviously lost into the gland tissues.4. Both these fractions of the fluid flowing into the gland when the outflow level was high could be reduced by injecting the alpha-receptor agonist phenylephrine. Bradykinin, which like phenylephrine is known to contract salivary myoepithelial cells, had the same effect on the two inflow volumes.5. It is concluded that myoepithelial contraction reduced the distensibility of the luminal system and in addition supported the acini, thereby diminishing backflow into the glandular tissues and enabling the gland to discharge saliva against a high pressure.6. Morphologically it was found that in resting glands PAS-positive saliva was displaced from the ductal system when the outflow cannula was raised, but it was preserved in the lumina under similar conditions when the myoepithelial cells were being stimulated by phenylephrine or bradykinin.7. Although sympathetic secretion could be maintained against a head of pressure, so long as it was accompanied by myoepithelial contraction, the increased force caused by the secretion led to disruptive damage of striated ducts which are the first part of the luminal system not supported by myoepithelial cells.8. The morphological findings reinforce the belief that contraction of myoepithelial cells gives active support to the underlying parenchyma.

Animals↗
PubMed1977

Movement of horseradish peroxidase in submandibular glands of dogs after ductal injection.

Small volumes of solutions of a tracer enzyme, horseradish peroxidase (HRP), have been injected retrogradely via the main duct of submandibular glands in dogs, and the distribution of the peroxidase reaction product within the glands has been studied light microscopically and electron microscopically at different times after the injection. Tissue taken immediately after injections of 0.25 ml, given over 10 sec, showed that HRP had penetrated into the interstitial spaces of the gland. It was usually irregularly distributed and appeared to have reached the interstices of the gland by passing through the intercellular junctions of adjacent acinar cells. In time the tracer gradually disappeared from the interstices of the gland. Most of this removal was probably via lymphatic and blood vessels, into both of which peroxidase rapidly passed after ductal injection. At 5 hours after the HRP injection only very weak interstitial staining was present and at later times none was detected. An inflammatory reaction occurred in the gland, starting within minutes after the injection of this foreign protein and reaching a peak after about 12 hours. The events in dogs and those occurring in rabbits under similar experimental conditions have been compared. This study has given some indication how foreign substances may be distributed after retrograde injection into salivary glands.

Animals↗
PubMed1976

Effects of heterologous cross-suture between the postganglionic sympathetic and the preganglionic parasympathetic nerve trunks of submandibular glands in cats.

After sectioning the postganglionic adrenergic sympathetic nerve trunk for the submandibular gland, as close to the submandibular artery as practicable, its central end was sutured to the peripheral end of the preganglionic cholinergic parasympathetic nerve trunk for the gland, the chorda, which had been sectioned where it left the lingual nerve. The effects of this heterologous cross-sature were studied at different times, up to 1 year afterwards, by assessing the physiological and pharmacological responses of the glands and the neuro-histochemical changes in the nerve trunks and in the nerves within the glands. In all cases adrenergic sympathetic nerves grew across the site of suture and down the erstwhile cholinergic parasympathetic trunk, eventually to develop connections in the gland. In some cases the functional adrenergic reinnervation of the submandibular gland appeared to result exclusively or predominantly from the direct downgrowth of adrenergic axons to the gland, via the crossed nerves. In other cases however, in addition to a direct glandular reinnervation, there was some physiological and morphological evidence which suggested that possible heterogneous synaptic contracts may have been created between postganglionic sympathetic axons and cholinergic ganglion cells in the chorda nerve.

Animals↗
PubMed1976

Histological effects of ductal ligation of salivary glands of the cat.

Forty-two submandibular, 32 sublingual and 31 parotid glands have been examined microscopically after ductal ligation avoiding the nerves for periods from 1 day to 1 yr. After an initial increase in size, there was over-all atrophy in all three glands. In the parotid gland the response was uniform and there was progressive atrophy until most of the acini were extremely atrophic. However, in the submandibular and sublingual glands the response was very variable, and although in some glands most of the acini were extremely atrophic, in other glands there was far less atrophy and most of the remaining acini appeared more or less similar to normal despite prolonged ligation. These results contrast with those of earlier experimental studies on ductal ligation, but have similarities with observations on the behaviour of human salivary glands.

Animals↗
PubMed1976

Inflammatory cells in duct-ligated salivary glands of the cat: a histochemical study.

Inflammatory cells were studied in submandibular, sublingual and parotid glands of cat following ductal ligation. Macrophages were seen within the parenchyma and associated with extravasated mucin, and were possibly of importance in removing secretory material. Neutrophils were seen interstitially and within the parenchyma. Eosinophils were involved in an initial inflammatory response in interstitial tissue. Fibrous connective tissue was more apparent.

Animals↗
PubMed1976

Acid phosphatase and peroxidase in "resting" acinar cells of the major salivary glands of cats and their possible movement into secretory granules.

After fixation of perarterial perfusion using an aldehyde mixture, salivary tissues were prepared for ultrastructural cytochemistry of acid phosphatase or peroxidase. Great variations in the distributions of the reaction product occurred, often within the same cell. Acid phosphatase staining occurred not only in lysosomes and sometimes in a GERL system, but a diffuse cytoplasmic component was also found in submandibular central acinar cells and to a lesser extent in parotid acini and variable staining occurred in the secretory granules of these cells. Peroxidase was variably associated with rough endoplasmic reticulum in submandibular demilunar cells, parotid acini, and more strongly in some sublingual cells. The secretory granules of the latter were darkly stained, but in parotid granules there was variable staining and least staining occurred in the granules of submandibular demilunes. These results are thought to indicate that not all enzymes present in secretory granules have reached there by an elective secretory process. Sometimes they appear to have entered the granules haphazardly, possibly having been enzymes associated with intracellular cisternal channels for transport or metabolism of other secretory substances and ultimately to have passed into the cisternal channels by chance or as part of a natural removal of redundant material.

Acid Phosphatase↗
PubMed1976

The effects of ductal ligation on the parenchyma of salivary glands of cat studied by enzyme histochemical methods.

Submandibular, sublingual and parotid glands of cat have been studied following periods of ductal ligation ranging from 1 day to 1 year. An increased prominence of granules of acid phosphatase, beta-glucuronidase and E600-resistant esterase reaction products was sometimes seen in acinar cells and atropic striated ductal cells, and probably represents increased lysosomal enzymic activity, which may be of importance in the adapation of the parenchyma to the altered environment. Other reaction products often appeared to be at normal levels in parenchymal structures that were not very atrophic, and at reduced levels in those that were very atrophic, suggesting a reduction of functional activity in these structures.

Acid Phosphatase↗
PubMed1976

Movement of horseradish peroxidase in rabbit submandibular glands after ductal injection.

Horseradish peroxidase (HRP) has been used as a tracer to study movements of solutions injected retrogradely via the duct of submandibular glands in rabbits. 0.1 ml of solution was injected either manually or by a constant hydrostatic pressure, and the subsequent distribution of HRP in the gland and duct at different times after injection has been examined histochemically at light and electron microscopical levels. Shortly after the injections, strong interstitial staining for peroxidase resulted from passage between acinar cells. Some sites of cellular uptake were observed and staining occurred in some ductal cells even when the duct had been cut at the hilum to minimize pressure effects. It is not known whether this diffuse uptake represents a physiological or pathological phenomenon. Some interstitial activity still remained 24 hr after injection but had disappeared by 48 hr. Inflammatory cells first appeared in the gland about 4hr after the injection and slowly increased up to about 24 hr after injection. The results indiate that the HRP reaches the interstices of the gland principally by penetration between acinar cells, and that the junctional complexes between striated duct cells appear to be more resistant to disruption by luminal pressures.

Animals↗