These are scanning electron microscopic images of the retina from the side of vitreous body. Image 2 and 3 are the higher magnification views of image 1. While (I) in image 1 is the cell just below inner limiting membrane, (G) is a ganglion cell and (V) is a blood vessel (capillary) in retina. Pericytes (P) in image 3 with processes (arrowhead) associate the endothelial tube in retina. The blood vessels in retina are quite different from those of choriocapillaris described here before.
These are SEM images of the capillaries in the mice skin (dermis of the back skin). These are regarded as normal capillaries. Pericytes (arrows in the upper and lower images) associate the endothelial tubes. The pericytes have cell bodies (arrows) and slender processes (arrowhead of the lower image). The connective tissue composed of collagen fibers was dissolved in advance and the blood vessels remained. The slender string like structures are elastic fibers remained after the treatment for removal of connective tissue.
These are the images of Bruch's membrane (No 1, B) and choriocapillaris (C). No. 1 is a view from RPE (retinal pigmented epithelium). No. 2 is a Bruch membrane composed of collagen fibers. No. 3 is a higher magnification view of the choriocapillaris in No. 1. No. 4 is a high magnification view of choriocapillaris. Endothelial cells of choriocapillaris have fenestrations.
Mice choriocapillaris has variation in morphology. In the upper image, choriocapillaris is a sheet of the endothelial cells (within the square line), while in the other areaschoriocapillaris shows mono-layered vascular network. In the middle image, the upper site is a sheet of the endothelial cells. The lower image is the high magnification view of the area surrounded with rectangle in the middle image. pericytes (arrows) fit the endothelial cells which have nuclear swellings. These findings show that remodeling of the choriocapillaris occurs in adult eye and it is by intussusception. Pericytes may remove from choriocapillaris in parallel with remodeling from sheets of endothelial cells to capillary network by VEGF from pigmented epithelial cells.
Pericyte processes and endothelial cells at outer (scleral) side of choriocapillaris. (P) is a pericyte process and (F) is a fenestrated endothelial cells. Lower image is a higher magnification view. Fenestration sparsely distributed around the pericyte process. Endothelial cells without pericytes have rich fenestration. Pericytes seem to restrict fenestration by VEGF. Indeed, endothelial cells have fenestration at inner (retinal) side of choriocapillaris, which is influenced by VEGF secretion from retinal pigmented epithelial cells (RPE).
This is a outer (scleral) side of the choriocapillaris that shows the pericyte associating the endothelial cells. The pericyte has long and slender processes indicated with white bars in the right high magnification image. The processes are branching. The pericyte observed here is similar to that of capillary in the ordinary vessels.
