scholarly journals Location and chemical composition of anionic sites in Bruch's membrane of the rat.

1982 ◽  
Vol 30 (3) ◽  
pp. 245-252 ◽  
Author(s):  
R M Pino ◽  
E Essner ◽  
L C Pino
Keyword(s):  
Chemical Composition ◽  
Heparan Sulfate ◽  
Basal Lamina ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Ruthenium Red ◽  
Morphological Evidence ◽  
Anionic Sites ◽  
Bruch's Membrane ◽  
Bruch’S Membrane

The location and chemical composition of anionic sites in Bruch's membrane (BM) were examined using cationic probe molecules demonstrable in electron microscopic preparations and tissue digestion with specific degradative enzymes. Ruthenium red and native lysozyme revealed densities distributed at regular intervals in two major components of BM: the basal laminae of the retinal pigment epithelium (RPE) and choriocapillary endothelium (EN). Staining was not observed with succinylated lysozyme (anionic). Colloidal iron also failed to stain BM components. Following crude heparinase treatment at 43 degrees C (specific for heparan sulfate) anionic sites in the RPE basal lamina were not demonstrable with either ruthenium red or native lysozyme. Sites in the EN basal lamina were not affected. Chondroitinase treatment removed almost all of the ruthenium red-positive material in the EN basal lamina; lysozyme binding here was markedly reduced. No changes were observed in the RPE basal lamina after chondroitinase digestion. There was no morphological evidence for site removal by either neuraminidase or leech hyaluronidase, although a detachment of the RPE from BM often occurred after incubation of eye tissue in the latter. Pronase E removed all stainable material. These findings indicate that anionic sites in BM consist to a large extent of chondroitin sulfates and heparan sulfate.

Fine Structure of the Retinal Pigment Epithelium, Bruch's Membrane, and Choriocapillaris in the Northern Pike (Esox lucius)

1974 ◽  
Vol 31 (10) ◽  
pp. 1601-1605 ◽  
Author(s):  
C. R. Braekevelt
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Retinal Pigment Epithelium ◽  
Epithelial Cell ◽  
Basal Lamina ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Northern Pike ◽  
Bruch's Membrane ◽  
Bruch’S Membrane

The fine structure of the retinal pigment epithelium, Bruch's membrane, and the choriocapillaris has been studied by light and electron microscopy in the adult northern pike (Esox lucius).The pigment epithelium is composed of a single layer of large cells. Each epithelial cell has abundant mitochondria, smooth endoplasmic reticulum, myeloid bodies, phagosomes, and pigment granules. Rough endoplasmic reticulum and ribosomes are scarce.The scleral or basal border of the epithelial cell is not infolded whereas the vitreal or apical surface displays numerous, fine, elongated processes which surround the inner and outer segments of the photoreceptors.Bruch's membrane is composed of three layers. The innermost layer is the basal lamina of the pigment epithelium. The outermost layer is the basal lamina of the choriocapillaris endothelium. Between these basal laminae is a layer of fine fibrils. The overall thickness of Bruch's membrane is 3.5–4 μ posteriorly.The endothelial wall of the choriocapillaris bordering Bruch's membrane is typically very thin but nonfenestrated. Vesicles are common in the endothelial cytoplasm.This region of the pike eye differs morphologically from that described for most other vertebrates.

scholarly journals Genetic LAMP2 deficiency accelerates the age-associated formation of basal laminar deposits in the retina

2019 ◽  
Vol 116 (47) ◽  
pp. 23724-23734 ◽  
Author(s):  
Shoji Notomi ◽  
Kenji Ishihara ◽  
Nikolaos E. Efstathiou ◽  
Jong-Jer Lee ◽  
Toshio Hisatomi ◽  
...  
Keyword(s):  
Basal Lamina ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Bruch's Membrane ◽  
Bruch’S Membrane ◽  
Rpe Cells ◽  
Age Related ◽  
Deficient Mice

The early stages of age-related macular degeneration (AMD) are characterized by the accumulation of basal laminar deposits (BLamDs). The mechanism for BLamDs accumulating between the retinal pigment epithelium (RPE) and its basal lamina remains elusive. Here we examined the role in AMD of lysosome-associated membrane protein-2 (LAMP2), a glycoprotein that plays a critical role in lysosomal biogenesis and maturation of autophagosomes/phagosomes. LAMP2 was preferentially expressed by RPE cells, and its expression declined with age. Deletion of the Lamp2 gene in mice resulted in age-dependent autofluorescence abnormalities of the fundus, thickening of Bruch’s membrane, and the formation of BLamDs, resembling histopathological changes occurring in AMD. Moreover, LAMP2-deficient mice developed molecular signatures similar to those found in human AMD—namely, the accumulation of APOE, APOA1, clusterin, and vitronectin—adjacent to BLamDs. In contrast, collagen 4, laminin, and fibronectin, which are extracellular matrix proteins constituting RPE basal lamina and Bruch’s membrane were reduced in Lamp2 knockout (KO) mice. Mechanistically, retarded phagocytic degradation of photoreceptor outer segments compromised lysosomal degradation and increased exocytosis in LAMP2-deficient RPE cells. The accumulation of BLamDs observed in LAMP2-deficient mice was eventually followed by loss of the RPE and photoreceptors. Finally, we observed loss of LAMP2 expression along with ultramicroscopic features of abnormal phagocytosis and exocytosis in eyes from AMD patients but not from control individuals. Taken together, these results indicate an important role for LAMP2 in RPE function in health and disease, suggesting that LAMP2 reduction may contribute to the formation of BLamDs in AMD.

scholarly journals Utilizing Recombinant Spider Silk Proteins To Develop a Synthetic Bruch’s Membrane for Modeling the Retinal Pigment Epithelium

2019 ◽  
Vol 5 (8) ◽  
pp. 4023-4036 ◽  
Author(s):  
Thomas I. Harris ◽  
Chase A. Paterson ◽  
Farhad Farjood ◽  
Ian D. Wadsworth ◽  
Lori Caldwell ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Spider Silk ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Bruch's Membrane ◽  
Bruch’S Membrane ◽  
Silk Proteins

Retinal Pigment Epithelium Wound Healing in Human Bruch’s Membrane Explants

2003 ◽  
Vol 44 (5) ◽  
pp. 2199 ◽  
Author(s):  
Hao Wang ◽  
Yoshihiko Ninomiya ◽  
Ilene K. Sugino ◽  
Marco A. Zarbin
Keyword(s):  
Wound Healing ◽  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Bruch's Membrane ◽  
Bruch’S Membrane

Bruch’s membrane pathology: A mechanistic perspective

2020 ◽  
Vol 30 (6) ◽  
pp. 1195-1206 ◽  
Author(s):  
Aishwarya Murali ◽  
Subramanian Krishnakumar ◽  
Anuradha Subramanian ◽  
Sowmya Parameswaran
Keyword(s):  
Extracellular Matrix ◽  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Vital Role ◽  
Age Related Macular Degeneration ◽  
Ocular Diseases ◽  
Bruch's Membrane ◽  
Bruch’S Membrane ◽  
Age Related

Bruch’s membrane, an extracellular matrix located between the retinal pigment epithelium and the choroid, plays a vital role as structural and functional support to the retinal pigment epithelium. Dysfunction of Bruch’s membrane in both age-related macular degeneration and other ocular diseases is caused mostly by extracellular matrix degeneration, deposit formation, and angiogenesis. Although these factors are dealt in greater detail with respect to the cells that are degenerated such as the retinal pigment epithelium and the endothelial cells, the pathology involving the Bruch’s membrane is often underrated. Since in most of the macular degenerations early degenerative changes are also observed in the Bruch’s membrane, addressing only the cellular component without the underlying membrane will not yield an ideal clinical benefit. This review aims to discuss the factors and the mechanisms affecting the integrity of the Bruch’s membrane, which would aid in developing an effective therapy for these pathologies.

Sign in / Sign up

Export Citation Format

Share Document