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Biomedical subjects

I Grierson

Publications and source records attributed to I Grierson.

At least 163 records · Page 9Linked to original sources
PubMed1978

Effects of pilocarpine on the morphology of the human outflow apparatus.

The morphology of the outflow apparatus in human eyes which had been treated topically with either 2 or 4% pilocarpine on 4 occasions at 6-hourly intervals before enucleation was compared with an untreated control series of eyes from patients in a similar age range. In the pilocarpine-treated group the scleral spur was pulled posteriorly and internally, so that the angle formed by the scleral spur and the scleral sulcus was significantly greater in the treated than the untreated series. The change in attitude of the scleral spur produced widening of the spaces between the corneoscleral trabeculae and distension of the endothelial meshwork. It was shown from counts of giant vacuoles in the endothelium of Schlemm's canal that the incidence of giant vacuoles in the pilocarpine-treated group was greater than twice that in the controls. It would appear that pilocarpine produces alterations in the configuration of the outflow apparatus which would promote the drainage of aqueous humour.

Adult↗
PubMed1977

Pressure effects on the distribution of extracellular materials in the rhesus monkey outflow apparatus.

An electron-microscopic investigation was conducted to determine the distribution of extracellular materials in the rhesus monkey outflow apparatus at various maintained levels of intraocular pressure. Intraocular pressure was maintained at either 0,8, 15, 22, 30, or 50 mm Hg, by an intracameral needle attached to a reservoir system for a period of 1 h. Thereafter the eyes were fixed either by intracameral perfusion of glutaraldehyde at the appropriate pressure level, or by carotid perfusion of the fixative, or by rapid enucleation and immersion fixation. The electron-dense cationic stains, colloidal thorium and colloidal iron were used to indicate the presence of carbohydrate-rich extracellular materials in the drainage tissues. In the control tissue (15 mm Hg), heavy concentrations of stain were detected within the cores of the trabeculae and in the extracellular spaces of the endothelial meshwork. With pressure elevation there was a progressive decrease in the surface staining on the meshwork cells, an increase in staining intensity within the trabecular cores, and a 'washout' of extracellular materials from the spaces of the endothelial meshwork. The washout was thought to occur via giant vacuoles up to 30 mm Hg, but at 50 mm Hg the process was accelerated by loss of association between the cells of the canal endothelial monolayer. Over the entire pressure range 0 to 50 mm Hg, there was an increase in the staining on the apical surface of the canal endothelium which was associated with a decrease in the incidence of micropinosomes.

Animals↗
PubMed1977

Macrophage infiltration in the human retina.

The retinal tissues were examined by light microscopy and by scanning and transmission electron microscopy in a human eye in which there was extensive infiltration by macrophages. The stimulus to macrophagic infiltration was an immune response in a mixed sympathetic and lens-induced ophthalmitis which occurred after surgical treatment for glaucoma. The inflammatory infiltrate was so exuberant that the cells were considered to be predominantly exogenous and the sites of entry into the eye included the pars plana, the optic disc, and the retinal and choroidal blood vessels. Within the retina it appeared that the macrophages migrated via the nerve fibre layer and via the subretinal and subpigment epithelial spaces.

Glaucoma↗
PubMed1977

Light microscopic quantitation of the endothelial vacuoles in Schlemm's canal.

Twelve rhesus monkeys were used for an experiment in which intraocular pressure was maintained at various levels between 0 and 50 mm Hg for one hour. A quantitative light microscopic analysis was made of the changes in the vacuolation of the endothelium lining Schlemm's canal. At 0 mm Hg, giant vacuoles were not found; at 8 mm Hg the counts of vacuoles were significantly lower than the corresponding 15 mm Hg controls; at 22 and 30 mm Hg the counts were significantly higher than the 15 mm Hg counts; and at 50 mm Hg 71 counts of vacuoles were less than at 22 and 30 mm Hg. Within the range of 8 to 30 mm Hg, change in pressure was shown to produce alterations in both vacuole numbers and their dimensions. The number of vacuoles increased linearly with increase in pressure, whereas mean vacuolar volume increased in a nonlinear manner.

Animals↗
PubMed1977

The appearance of the outflow apparatus of the eye after staining with ruthenium red.

The outflow apparatus from adult baboon and rabbit eyes was stained with the inorganic dye ruthenium red. The ruthenium reaction product coated the surface of the trabecular meshwork cells and the canalicular endothelial cells. Deposits also impregnated the various connective tissue elements within the trabeculae and the extracellular spaces of the endothelial meshwork. A fine fibrillar network could also be identified with ruthenium red and this was present in the trabecular cores and the extracellular spaces of the endothelial meshwork. It was considered that the fibrillar network may represent a matrix of glycosaminoglycans and glycoproteins. The significance of these materials in relation to aqueous outflow was discussed.

Animals↗
PubMed1977

Posterior vitreoretinal malformation. A clinicopathologic case report.

A pathological examination was performed on the eye of a 2-year-old male child. The basic abnormality was a vitreoretinal malformation. Study of the tissue by light and electron microscopy provided evidence to suggest that the case should be considered as a primary abnormality of the posterior vitreous and that the retinal changes were the result of a traction deformity.

Child, Preschool↗
PubMed1977

Particulate phagocytosis by trabecular meshwork endothelium.

We studied the phagocytic response in the trabecular meshwork of rabbits to the debris released by photocoagulation of the iris. Four cell types exhibited phagocytosis: native meshwork endothelium, histiocytic macrophages, polymorphonuclear leukocytes and corneal endothelial cells. Nienty days after the photocoagulation both the lining cells and the trabecular beams of the meshwork had returned to normal.

Animals↗
PubMed1976

Post-mortem changes in the rabbit retina. A study by light microscopy.

The course of post-mortem changes in rabbit retina has been followed. Short post-mortem periods are accompanied by degenerative changes limited mainly to the visual cells and retinal pigment epithelium. Long post-mortem periods are associated with degenerative changes throughout the retina. Retinal tissue maintained at room temperature was less affected than that kept at body temperature (37degreesC). Post-mortem changes are similar to those observed following periods of pressure induced ischaemia and it is thought that the mechanical effects of pressure on retinal tissue are minimal at the level of resolution afforded by light microscopy.

Animals↗
PubMed1975

Pressure effects on the endothelium of the trabecular wall of Schlemm's canal: a study by scanning electron microscopy.

The scanning electron microscope was used to compare the appearances of the endothelial monolayer of the trabecular wall of Schlemm's canal in the rhesus monkey after exposure to intracameral pressures of 8, 15 and 22 mm Hg for one hour. Over this pressure range, the bulges in the spindle-shaped structures in the monolayer became rounder in shape and the number of openings on the surface was apparently greater at 22 mm Hg than at 15 and 8 mm Hg. A quantitative comparison between the tissue at 8 and 15 mm Hg showed a statistically significant increase in the number of openings on the bulges at 15 mm Hg.

Animals↗
PubMed1975

Pressure-induced changes in the ultrastructure of the endothelium lining Schlemm's canal.

In a transmission electron microscopic investigation of the endothelium lining Schlemm's canal subjected to graded levels of intraocular pressure (0 to 50 mm Hg for one hour), there was an increase in the number of vacuolar structures with the increase in pressure (range, 8 to 30 mm Hg). At 0 mm Hg, giant vacuoles were absent, while at 50 mm Hg their numbers were less than at 22 and 30 mm Hg. Vacuoles were invaginations either from the meshwork or from the canal surface of the endothelium. A few were transcellular channels that possibly served as a pressure-sensitive outflow system. In addition, the numbers of nonvacuolar transcellular channels and minipores increased with an increase in pressure while the numbers of pinocytotic and micropinocytotic vesicles decreased. The changes were not accompanied by alterations in organelles associated either with protein or energy production. At 50 mm Hg, breaches in the endothelium lining the trabecular wall were obvious and aqueous outflow was considered to be by nonphysiologic routes.

Animals↗