12.1.4 POJA-L2568+2576+
2578+2579+3574+2581
Retina and choroid of the eye
12.1.4 POJA-L2568+2576+2578+2579+3574+2581
Title: Retina and choroid of the eye
Description:
(A, B): Retina, stain Azan, monkey. (C): Deeper part of the retina, stain basic fuchsin semi-thin plastic section, gerbil. The rectangle in (C) is detailed with electron microscopy shown in (D, E, F) with the choriocapillary layer and membrane of Bruch (double arrowed bar).
Electron micrographs (D, E) gerbil and (F) human.
(A, B): (1) Nerve nerve fibre layer and inner limiting membrane.
(2) Ganglion cell layer.
(3) Inner plexiform layer.
(4) Inner nuclear layer.
(5) Outer plexiform layer.
(6) Outer nuclear layer.
(7) Inner and outer segments of rods and cones.
(8) Retinal pigmented epithelium (RPE).
(9) Choroid with blood vessels and pigmented melanocytes.
(C :) Retinal pigmented cell layer (RPE) with choroid. The RPE shows apically abundant but slender pigmented projections in close contact with the outer segments of cones and rods. The smaller and dark pink granules are lysosomes. In the latter phagocytised remnants of membranous discs (containing lipids and iodopsin or rhodopsin) out of the tips of the outer segments are destroyed.
The white area at the base of the RPE represents the basal labyrinth formed by basal invaginations of the cell membrane (active transport). These invaginations are shown in (D, E).
In (C) the choriocapillaris shows many capillaries, pigment-loaded melanocytes and fibroblasts. The endothelial cells are fenestrated in the electron microscope.
The Bruch’s membrane is indicated by arrows in the rectangle in the light microscope (B, C). Ultrastructurally the Bruch’s membrane (double arrowed bars) appears to be composed of the basement membrane of the RPE, a collagen layer and an elastic layer (D - F).
Background 1: In light microscopy (B, C) the Bruch’s membrane is about 2 micron thick (young eye) that thickens with ageing.
The membrane shows prominent basophilia and with ageing more intense PAS-staining due to increased deposited ECM
(extracellular matrix). With progressive ageing as well as in diseases like diabetic retinopathy, pseudoxanthoma elasticum e.a.
abnormal deposits of amorph, granular material or calcification within the elastic material are shown. These ‘Drusen’ formations
could also be observed as discontinuous deposits of electron-dense/vesicular material between the RPE and the Bruch’s membrane.
Background 2: The blood-retinal barrier (BRB) is composed of an inner and outer barrier.
The inner barrier (BRB) is comprised by the endothelium of the choriocapilaris (analogue to the blood-brain barrier) and is thus involved
in retinal homeostasis. The endothelial tight junctions of the choriocapillaries mediate selective diffusion of molecules from blood to the pigmented retinal epithelium (RPE).
The outer barrier (BRB) is formed by tight junctions of the RPE and regulates a.o. the transport of dissolved nutrients out from the
choroid blood vessels. Alterations in this BRB can result in macular edema. Alterations are also associated with diabetic retinopathy
and age-related macular degeneration.
Keywords/Mesh: eye, retina, Bruch’s membrane, choriocapillaris, choroid, histology, electron microscopy, POJA collection
Title: Retina and choroid of the eye
Description:
(A, B): Retina, stain Azan, monkey. (C): Deeper part of the retina, stain basic fuchsin semi-thin plastic section, gerbil. The rectangle in (C) is detailed with electron microscopy shown in (D, E, F) with the choriocapillary layer and membrane of Bruch (double arrowed bar).
Electron micrographs (D, E) gerbil and (F) human.
(A, B): (1) Nerve nerve fibre layer and inner limiting membrane.
(2) Ganglion cell layer.
(3) Inner plexiform layer.
(4) Inner nuclear layer.
(5) Outer plexiform layer.
(6) Outer nuclear layer.
(7) Inner and outer segments of rods and cones.
(8) Retinal pigmented epithelium (RPE).
(9) Choroid with blood vessels and pigmented melanocytes.
(C :) Retinal pigmented cell layer (RPE) with choroid. The RPE shows apically abundant but slender pigmented projections in close contact with the outer segments of cones and rods. The smaller and dark pink granules are lysosomes. In the latter phagocytised remnants of membranous discs (containing lipids and iodopsin or rhodopsin) out of the tips of the outer segments are destroyed.
The white area at the base of the RPE represents the basal labyrinth formed by basal invaginations of the cell membrane (active transport). These invaginations are shown in (D, E).
In (C) the choriocapillaris shows many capillaries, pigment-loaded melanocytes and fibroblasts. The endothelial cells are fenestrated in the electron microscope.
The Bruch’s membrane is indicated by arrows in the rectangle in the light microscope (B, C). Ultrastructurally the Bruch’s membrane (double arrowed bars) appears to be composed of the basement membrane of the RPE, a collagen layer and an elastic layer (D - F).
Background 1: In light microscopy (B, C) the Bruch’s membrane is about 2 micron thick (young eye) that thickens with ageing.
The membrane shows prominent basophilia and with ageing more intense PAS-staining due to increased deposited ECM
(extracellular matrix). With progressive ageing as well as in diseases like diabetic retinopathy, pseudoxanthoma elasticum e.a.
abnormal deposits of amorph, granular material or calcification within the elastic material are shown. These ‘Drusen’ formations
could also be observed as discontinuous deposits of electron-dense/vesicular material between the RPE and the Bruch’s membrane.
Background 2: The blood-retinal barrier (BRB) is composed of an inner and outer barrier.
The inner barrier (BRB) is comprised by the endothelium of the choriocapilaris (analogue to the blood-brain barrier) and is thus involved
in retinal homeostasis. The endothelial tight junctions of the choriocapillaries mediate selective diffusion of molecules from blood to the pigmented retinal epithelium (RPE).
The outer barrier (BRB) is formed by tight junctions of the RPE and regulates a.o. the transport of dissolved nutrients out from the
choroid blood vessels. Alterations in this BRB can result in macular edema. Alterations are also associated with diabetic retinopathy
and age-related macular degeneration.
Keywords/Mesh: eye, retina, Bruch’s membrane, choriocapillaris, choroid, histology, electron microscopy, POJA collection