Structural Specializations of Human Retinal Glial Cells

Ramı́rez, José M.; Triviño, Alberto; Ramírez, Ana I.; Salazar, Juan; García–Sánchez, J.

doi:10.1016/0042-6989(95)00322-3

Cited by 75 publications

(65 citation statements)

References 38 publications

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“…2). The dark appearance of the cytoplasm of Mu$ ller cells represents a reliable criterion for their ultrastructural identification that has already been applied, by others, to Tupaia belangeri (Reichenbach et al 1995) as well as many other species (Holla$ nder et al 1991 ;Ramirez et al 1996). We never observed cell processes revealing transitions between electron-dense and electron-lucent cytoplasm.…”

Section: mentioning

confidence: 68%

To what extent are the retinal capillaries ensheathed by Müller cells? A stereological study in the tree shrew Tupaia belangeri

2000

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The cellular ensheathment of capillaries in the 3 outer capillary layers of the central retina of the adult tree shrew Tupaia belangeri was studied quantitatively by transmission electron microscopy. Using a stereological approach, the relative surface of capillary basal lamina ensheathed by Mu$ ller cells and by nonmacroglial cells (collectively termed non-Mu$ ller cells) was estimated in 5 animals. The participation of Mu$ ller cells was distinctly different in the 3 capillary layers studied. In the outermost capillary layer 1, the mean (standard deviation) percentage surface coverage by non-Mu$ ller cell processes was 46n8 (15n3) %. Much less of the capillary basal lamina was ensheathed by non-Mu$ ller cells in capillary layers 2 and 3 (3n0 (2n1) % and 0n3 (0n3) % respectively). The observed total variation of the stereological estimates for the surface fraction of Mu$ ller cells (expressed as the between-subject coefficient of variation) was significantly higher in capillary layer 1 (28n8 %) compared with capillary layers 2 (2n2 %) and 3 (0n3 %). In capillary layer 1, the high observed total variation was due to a high biological variation among animals for the fractions of both Mu$ ller cell and non-Mu$ ller cell ensheathment. The rare occurrence of direct contacts between the capillary basal lamina and the perikarya of either microglial cells (capillary layer 3) or amacrine cells (capillary layer 2) corresponded well to the low stereological values obtained for the relative capillary surface ensheathed by non-Mu$ ller cells in these capillary layers. Previously, extensive and frequent contacts between the basal lamina of capillaries belonging to capillary layer 1 and horizontal cells had been observed in single sections. The present study quantitatively demonstrates a marked paucity of macroglial investment of capillaries located in capillary layer 1 of Tupaia. It can be concluded that horizontal cells ensheath most of the capillary surface not invested by Mu$ ller cells. In the retina of the adult tree shrew Tupaia belangeri, the basal lamina of capillaries located between the nerve fibre layer and the ganglion cell layer (capillary layer 4) is invested by the processes of Mu$ ller cells and by astrocytes which are absent from the outer parts of the retina. Retinal capillaries in the 3 outer capillary layers (capillary layers 1 to 3) are incompletely invested by the processes of Mu$ ller cells. To an extreme, the perikarya and the processes of horizontal cells abut on up to 90 % of the basal lamina of single capillary cross sections located between the outer

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Section: mentioning

confidence: 68%

To what extent are the retinal capillaries ensheathed by Müller cells? A stereological study in the tree shrew Tupaia belangeri

2000

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“…5D,E). It is in the neuroligin 3 positive regions that extensive connections are made between the astrocytes and Muller cells, and between adjacent astrocytes (Ramirez et al, 1996). In the developing spinal cord, at both the embryonic and early postnatal stages, neuroligin is strongly expressed in the midline raphe glial structure (Fig.…”

Section: Discussionmentioning

confidence: 98%

“…Neuroligin 1/3 is expressed in the honeycomb-like array of astrocytes that is closely associated with the retinal ganglion cells and the blood vessels in the ganglion cell layer (Fig. 5D) (Ramirez et al, 1996). Neuroligin 1/3 also labels the astrocytic processes found in the nerve fiber layer (NFL) arranged along the blood vessels and surrounding bundles of axons, as well as the astrocytic processes of the inner nerve layer (INL) as they follow the capillaries.…”

Section: Neuroligin 3 Is Expressed In Retinal Astrocytesmentioning

confidence: 99%

Neuroligin 3 is a vertebrate gliotactin expressed in the olfactory ensheathing glia, a growth‐promoting class of macroglia

Gilbert

Smith

Roskams

et al. 2001

Glia

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The molecular mechanisms that drive glia-glial interactions and glia-neuronal interactions during the development of the nervous system are poorly understood. A number of membrane-bound cell adhesion molecules have been shown to play a role, although the precise nature of their involvement is unknown. One class of molecules with cell adhesive properties used in the nervous system is the serine-esterase-like family of transmembrane proteins. A member of this class, a glia-specific protein called gliotactin, has been shown to be necessary for the development of the glial sheath in the peripheral nervous system of Drosophila melanogaster. Gliotactin is essential for the development of septate junctions in the glial sheath of individual and neighboring glia. Mutations that remove this protein result in paralysis and eventually death due to a breakdown in the glial-based blood-nerve barrier. To study the role of gliotactin during vertebrate nervous system development, we have isolated a potential vertebrate gliotactin homologue from mice and rat and found that it corresponds to neuroligin 3. Using a combination of RT-PCR and immunohistochemistry, we have found that neuroligin 3 is expressed during the development of the nervous system in many classes of glia. In particular neuroligin 3 is expressed in the olfactory ensheathing glia, retinal astrocytes, Schwann cells, and spinal cord astrocytes in the developing embryo. This expression is developmentally controlled such that in postnatal and adult stages, neuroligin 3 continues to be expressed at high levels in the olfactory ensheathing glia, a highly plastic class of glia that retain many of their developmental characteristics throughout life.

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“…29,30) There is mounting evidence that glial cells are important in the maintenance of normal neuronal activity, and that they protect the integrity of the nervous system by regulating bidirectional communication. 31,32) Glial cells within the nervous system are cited increasingly frequently as participants in the patholog- ÃÃ Significantly different as compared to the control group, P < 0:01. ical course of neuronal damage due to mechanical, ischemic, and various other types of injury. A characteristic feature of nerve tissue injury or stress is the activation of glial cells, which is characterized by an increase in the size and number of glial cells and the upregulation of intermediate filament proteins within the affected tissue.…”

Section: Discussionmentioning

confidence: 99%

Short-Term Hyperhomocysteinemia-Induced Oxidative Stress Activates Retinal Glial Cells and Increases Vascular Endothelial Growth Factor Expression in Rat Retina

Lee¹,

Lee²,

Kim³

et al. 2007

Bioscience, Biotechnology, and Biochemistry

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Structural Specializations of Human Retinal Glial Cells

Cited by 75 publications

References 38 publications

To what extent are the retinal capillaries ensheathed by Müller cells? A stereological study in the tree shrew Tupaia belangeri

To what extent are the retinal capillaries ensheathed by Müller cells? A stereological study in the tree shrew Tupaia belangeri

Neuroligin 3 is a vertebrate gliotactin expressed in the olfactory ensheathing glia, a growth‐promoting class of macroglia

Short-Term Hyperhomocysteinemia-Induced Oxidative Stress Activates Retinal Glial Cells and Increases Vascular Endothelial Growth Factor Expression in Rat Retina

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