Abstract
Purpose: :
The suprachoroid is usually presented histologically in slices vertical to the scleral plane, and appears as a membranous tissue of several layers consisting of melanocytes and fibroblasts as its cellular components. Because the cells lie laterally continuous, resembling cobblestones in appearance, it seems water-tight through its radial direction. A part of the aqueous humor through the uveoscleral flow is known to reach the suprachoroid, and fluid leaking from the choriocapillaris of the choroid is also expected to pass through the suprachoroid into the episcleral tissues. We studied the three-dimensional structure of suprachoroidal tissue in rabbits to examine the route through which ocular fluid can pass from inner to outer tissue to reach the sclera.
Methods: :
Pigmented rabbits were used. Eyeballs were enucleated and the posterior hemisphere immersed in Krebs solution. After removal of the vitreous, retina, and inner parts of the choroid, the suprachoroid on the sclera was observed under a stereomicroscope in Krebs solution.
Results: :
The suprachoroid appeared as a membranous tissue of several layers as seen in histological slices, but there were spaces between the layers, and each layer had numerous round-shaped pores of various sizes which made the inter layer spaces appear as a single united compartment in the stereomicroscopic observation. Because the pores existed randomly on each plane, some pores were lined up with the pores on the layer below while others were not. Parts of each layer continued into the next one forming a multistory parking garage-like structure that made the suprachoroidal tissue appear topologically as one whole plane. The layers were elastic and their outermost parts merged into the scleral tissue, showing a construction like strings on a bow-shaped sclera as seen in a cross section.
Conclusions: :
Three-dimensional morphologic observation of rabbit suprachoroidal tissue under the stereomicroscope suggested that the ocular fluid can pass the suprachoroid through the pores of its membranous tissue plane and the inter spaces between the layers from inner to outer tissue to reach the sclera. Furthermore, valve function to the ocular fluid in a direction vertical to the sclera can be expected from its characteristic morphology.
Keywords: anatomy • choroid • aqueous