Johannes Gottanka

Severity of optic nerve damage in eyes with POAG is correlated with changes in the trabecular meshwork.

Purpose:We wished to determine whether eyes with primary open-angle glaucoma (POAG) and differing severity of optic nerve damage also have differences in severity of trabecular meshwork changes. Methods:The trabecular meshwork and optic nerve from 26 eyes (14 donors) with the clinical diagnosis of POAG were studied. Severity of disease ranged from increased intraocular pressure (IOP) without damage to eyes with severe visual field loss. Optic nerve cross-sections were examined with light microscopy, and axonal counts were determined. We studied the trabecular meshwork around the circumference of each eye, examining sections from each quadrant with light and transmission electron microscopy. Morphometric measurements were made of the components of the cribriform region and statistically correlated with the axonal counts by the Pearson correlation coefficient. Results:In eyes with advanced POAG, as determined by visual field loss, measurements of structures in the cribriform region of the trabecular meshwork and axon counts were in the same range as those reported previously in POAG. Axon counts showed a significant negative correlation with the amount of sheath-derived (SD) plaque material in the cribriform region: eyes with lower axon counts had larger amounts of SD plaques. Six eyes from four donors with increased pressure but no clinical signs of optic nerve damage showed no changes in axon counts and no increase in plaque material. Conclusions:Increasing severity of optic nerve damage in POAG is accompanied by an increase in the amount of SD plaque material in the trabecular meshwork.

Histologic findings in pigment dispersion syndrome and pigmentary glaucoma.

PurposeTo investigate the morphologic changes in the trabecular meshwork in a case series of eyes with pigment dispersion syndrome and pigmentary glaucoma, and surgical trabeculectomy specimens from eyes with pigmentary glaucoma. Materials and MethodsTrabecular meshworks from 6 whole eyes from 3 donors and 7 trabeculectomy specimens were studied by light and electron microscopy. Axonal counts from the whole eyes were correlated with qualitative and quantitative data of meshwork changes. ResultsChanges in the meshwork varied around the circumference of the eyes, but in all 6 eyes in most regions of the circumference there were numerous pigment granules within trabecular cells; pigment was not found within intertrabecular or cribriform spaces. In some regions of the circumference there was trabecular cell loss, loss of intertrabecular spaces, fusion of lamellae, and an increase in extracellular material under the inner wall of the canal. Separation of the normal tendinous connection to the canal wall cells was noted in some regions of all eyes. This change could be associated with regions of pathologic separation of the inner wall from the cribriform region, associated with partial obliteration of the lumen of the canal with cells and cell processes. In eyes with pronounced axon loss, meshworks showed most pronounced loss of trabecular cells and increased extracellular material. Trabeculectomy specimens had similar changes and, in addition, showed damaged trabecular cells and collapse of intertrabecular spaces without fusion of lamellae, consistent with artifacts from manipulation during surgery. ConclusionsLoss of trabecular cells, fusion of trabecular lamellae with collapse of intertrabecular spaces, increase in extracellular material, and obliteration of the canal were found in various amounts around the circumference of eyes with pigment dispersion syndrome and elevated intraocular pressure, and pigmentary glaucoma. These probably all contribute to the development of increased intraocular pressure. Meshworks from trabeculectomy specimens showed these findings and also showed artifactual damage of cells and loss of intertrabecular spaces. This suggests that handling during surgery may cause single trabeculectomy specimens to give only an incomplete picture of the pathophysiology of pigmentary glaucoma.

Ultrastructural Changes in the Trabecular Meshwork of Juvenile Glaucoma

Trabeculectomy specimens from 11 patients with juvenile glaucoma were studied by electron microscopy and quantitatively evaluated. In all cases, large amounts of extracellular material arranged in a fingerprint-like pattern, resembling basement-membrane-like material (FBM) was found, similar to that described in steroid-induced glaucoma. This material was found mainly within the inner cribriform and outer corneoscleral regions of the trabecular meshwork, and caused the cribriform layer to be greatly thickened. FBM was also intimately associated with trabecular cells, which frequently appeared activated. In 3 cases, there was also an increase in fine fibrillar material which resembled that found in eyes with steroid-induced glaucoma. The amount of sheath-derived plaque material, which is increased in primary open angle glaucoma, was greatly increased in the subendothelial layer adjacent to Schlemms canal.

Oocytes develop from interconnected cystocytes in the panoistic ovary of Nemoura sp. (Pictet) (Plecoptera : Nemouridae)

Abstract The 2 ovaries of Nemoura sp. (Plecoptera : Nemouridae) are comb-like and house about 60–70 ovarioles each. By ultrathin serial sections through a whole ovariole of a last-larval instar, we gathered information on its ultrastructure and 3-dimensional architecture. The germarial region contains several clusters of interconnected oogonia or oocytes. The intercellular bridges (ring canals) are filled with fusomes. Most of the fusomes assemble to polyfusomes and some of the intercellular bridges move together and their cells assemble to rosettes. Results indicate that existence of polyfusomes is not sufficient for rosette formation. The oogonia or oocytes of each cluster develop synchronously. Oocytes detach from clusters next to intercellular bridges. A transdetermination of oogonia to nurse cells does not occur. Thus, the stone flies remain true panoists.

Mayflies (Ephemeroptera), the most primitive' winged insects, have telotrophic meroistic ovaries

Germ line cell cluster formation in ovarioles of three different stages, each from a different mayfly species, was studied using ultra-thin serial sectioning. In the analysed ovariole of Cloeön sp., only one linear, zigzag germ line cell cluster was found, consisting of sibling cells connected by intercellular bridges which represent remnants of preceding synchronized mitotic cycles followed by incomplete cytokinesis. A polyfusome stretched through all sibling cells. At the tip of the ovariole, cytokinesis occurred without preceding division of nuclei; thus, intercellular bridges were lined up but the remaining cytoplasm between the bridges had no nuclei. The analysed Siphlonurus armatus vitellarium contained five oocytes at different stages of development. Each oocyte in the vitellarium was connected via a nutritive cord to the linear cluster of its sibling cells in the terminal trophic chamber. Each cluster had the same architecture as was found in Cloëon. The 3-dimensional arrangement and distribution of closed intercellular bridges strongly suggest that all five clusters are derived from a single primary clone. The position of oocytes within each cluster is random. However, each oocyte is embraced by follicular or prefollicular cells whilst all other sibling cells are enclosed by somatic inner sheath cells, clearly distinguishable from prefollicular cells. In the analysed ovariole of Ephemerella ignita, two small linear clusters were found in the tropharium beside two single cells, two isolated cytoplasmic bags with intercellular bridges but no nuclei, and some degenerating aggregates. One cluster was still connected to a growing oocyte via a nutritive cord. In all species the nurse cells remained small and no indications of polyploidization were found. We suggest that this ancient and previously unknown telotrophic meroistic ovary has evolved directly from panoistic ancestors.

The origin of extrinsic nitrergic axons supplying the human eye

Nitrergic nerve fibres of intrinsic and extrinsic origin constitute an important component of the autonomic innervation in the human eye. The intrinsic source of nitrergic nerves are the ganglion cells in choroid and ciliary muscle. In order to obtain more information on the origin of extrinsic nitrergic nerves in the human eye, we obtained superior cervical, ciliary, pterygopalatine and trigeminal ganglia from six human donors, and stained them for neuronal nitric oxide synthase (nNOS) and nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐D). In the superior cervical ganglia, nNOS/NADPH‐D‐positive varicose axons were observed whereas perikarya were consistently negative. Fewer than 1% of perikarya in the ciliary ganglia were labelled for nNOS/NADPH‐D. The diameter of nNOS/NADPH‐D‐positive ciliary perikarya was between 8 and 10 µm, which was markedly smaller than the diameter of the vast majority of negative perikarya in the ciliary ganglion. More than 70% of perikarya in the pterygopalatine ganglia were intensely labelled for both nNOS and NADPH‐D. In trigeminal ganglia, 18% of perikarya were nNOS/NADPH‐D‐positive. The average diameter of trigeminal nNOS/NADPH‐D perikarya was between 25 and 45 µm. Pterygopalatine and trigeminal ganglia are the most likely sources for extrinsic nerve fibres to the human eye.

Beta-adrenergic blocker therapy and the trabecular meshwork.

Abstract.Purpose: To determine whether β-adrenergic blocker (β-blocker) therapy for glaucoma causes changes in the trabecular meshwork due to underperfusion. Methods: Thirty-five eyes from 19 donors with primary open-angle glaucoma (POAG) were divided into three groups: eyes receiving β-blocker therapy along with standard medications, eyes receiving standard medications but no β-blockers, and eyes with elevated intraocular pressure but receiving no therapy. Transmission electron microscopy was used to assess the extracellular material of the cribriform region, the structure of the trabecular lamellae, and pigmentation of the trabecular cells. Six eyes from four normal donors were used as controls. Results: No specific changes in the trabecular meshwork were found in eyes receiving β-blocker therapy. The amount and composition of the extracellular matrix of the cribriform region and the morphology of the lamellae were similar among the three groups of eyes with POAG. Pigmentation of trabecular cells appeared to be a marker for aqueous flow, as significantly more cells contained pigment in regions of the meshwork with thin or normal lamellae than in regions with thickened and fused lamellae. These regions were variable around the circumference of the eye, and were similar between eyes with and without β-blocker therapy. Conclusion: β-Blocker therapy could not be proven to cause underperfusion changes in the trabecular meshwork or other discernible effects. Preferential pathways for aqueous flow probably exist within regions of the trabecular meshwork, as evidenced by lamellar appearance and pigmentation of the adjacent trabecular cells.

Alterations in anterior segment dimensions in eyes with retinitis pigmentosa

Abstract⊎ Background: In visually deprived primate eyes there is a correlation between alterations in growth parameters and changes in retinal neurotransmitters. Progressive retinal degeneration also leads to alterations in retinal neurotransmitters. In this study we wanted to investigate whether alterations in the dimensions of the anterior eye segment are also present in human donor eyes of patients with hereditary retinal degeneration. ⊎ Methods: Sagittal sections through anterior segments of 47 eyes from donors with different types of retinitis pigmentosa (RP) and of 59 eyes from normal donors were investigated morphometrically using a PC-based morphometric system. ⊎ Results:. In the RP eyes there was a significant shortening of the distance between the peripheral end of Descemets membrane and the posterior end of Schlemms canal and of the length of the pars plana of the ciliary body. These changes varied markedly among the different types of RP. The most pronounced shortenings were found in eyes of men with X-linked recessive RP, which had the most severe retinal changes. RP eyes showed, in contrast to normal eyes, significant age-related elongation of the ciliary body and the chamber angle. A significant increase of the axial diameter with age was also found in RP eyes. ⊎ Conclusion: Our study reveals for the first time that there are changes in the anterior segment dimensions in human eyes with hereditary retinal degeneration. Measurements of anterior eye segment parameters might provide additional indices for the severity of RP and for the diagnosis of RP subtypes.