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B E Sumner

Publications and source records attributed to B E Sumner.

31 records · Page 2Linked to original sources
PubMed1975

An ultrastructural study of normal and injured hypoglossal nuclei after injection of horseradish peroxidase.

The left hypoglossal nuclei of normal rats, and rats which had received left hypoglossal nerve axotomies 7-21 days previously, were studied by electron microscopy after injection of horseradish peroxidase as a marker of extracellular space and pinocytosis. Quantitative analysis showed that the number of pinocytotically-derived structures in presynaptic boutons was significantly increased in rats at 7, 14, and 21 days after axotomy when compared with normal rats. It was suggested that presynaptic boutons which became detached from injured neurones retracted by a membrane cycling mechanism involving pinocytotic uptake of bouton plasmalemma, without compensatory membrane production elsewhere. It was confirmed that the channels in the microglial cells communicated with the extracellular space.

Animals↗
PubMed1975

A quantitative study of subsurface cisterns and their relationships in normal and axotomized hypoglossal neurones.

A quantitative ultrastructural survey was made of subsurface cisterns and their association with overlying structures in the left hypoglossal nucleus of normal rats, and rats which had received left hypoglossal axotomies 7-84 days previously. Subsurface cisterns in normal rats occurred in some hypoglossal neurones, and, sporadically, in proximal dendrites. They were mostly subsynaptic, and often associated with Nissl substance; From 7-14 days postoperatively, when many somatic boutons temporarily lost contact with the perikaryal surface, and were replaced by a microglial sheath, the percentage of perikaryon with underlying cistern was significantly reduced. The Nissl substance was also dispersed at this stage, and not restored until 28 days postoperatively. At 21 days normal percentages of subsurface cistern were restored, but the cisterns were now mostly subastrocytic, an astrocytic sheath having replaced the microglial sheath. From 63 days onwards the cisterns were mostly subsynaptic again as boutons returned to the regenerating perikarya and the temporary astrocytic sheath disappeared. It is suggested that subsurface cisterns might alter the overlying perikaryal surface in some way during neuronal regeneration, causing certain boutons to adhere there.

Animals↗
PubMed1974

The effect of injury on two hydrolases in the hypoglossal nucleus, with quantitative data on N-acetyl-beta-glucosaminidase.

N-acetyl-beta-glucosaminidase and acid phosphatase were studied histochemically in sections of hypoglossal nuclei of normal adult male albino rats, and rats from 1 to 56 days after axotomy of the left hypoglossal nerve, or after injection of botulinum toxin into the left side of the tongue. Both axotomy and botulinum caused a diminution of neurone perikaryal glucosaminidase reaction product on the operated side, but an increase of reaction product elsewhere in the operated nucleus. Whereas the effect of axotomy lasted from 5 to 42 days post-operatively, that of botulinum ceased between 28 and 42 days. Axotomy and botulinum both caused an increase of neuronal acid phosphatase (after a short incubation time) from 2 to 21 days post-operatively in injured nuclei. Glucosaminidase reaction product measured microdensitometrically in isolated cells showed a statistically significant diminution in injured neurones at 18 days after axotomy. There was no change in the amount of reaction product per cell in pericytes, astrocytes, or non-astrocyte glia. Sections scanned quantitatively showed that normal and operated nuclei had a similar amount of reaction product, thus the neuronal diminution must be balanced by the increase elsewhere, either in the elevated numbers of non-astrocyte glia, or in the neuropil.

Acetylglucosaminidase↗
PubMedDate not supplied

A quantitative study of vascular permeability to horseradish peroxidase, and the subsequent fate of the tracer, in rat brains after portocaval anastomosis.

Labelled blood vessel segments, exudation patches, and pericytic granular cells were counted in sections of rat brain which had been fixed and tested with DAB from 3 min to 24 h after intravenous injection of horseradish peroxidase (HRP). In normal rats, 3 min after injection, only 1% of the total blood vessel segments had walls penetrated by HRP, but in rats 14 days after portocaval anastomosis (PCA) 44% of the total segments had labelled walls, a frequency of 3033 permeable segments/mm3 of brain. In normal rats no exudation patches were found, but after PCA there were seven patches/mm3 of brain. Maximum vascular wall labelling and maximum exudation occurred in the cerebellum and medulla of the operated rats. Hardly any pericytic cells were labelled 3 min after injection. In operated rats 2 h after injection of HRP, labelled vascular walls were fewer and exudation had disappeared, but 204 pericytic cells/mm3 of brain contained HRP-labelled granules, i.e. 60% of the total pericytes. Highest numbers were found in the most anterior section of the brain sample. Later after injection these numbers declined. It is suggested that most of the protein which leaked into the brain after PCA returned to the blood whence it came, but that some was captured and hydrolysed by the granular pericytes.

Animals↗