Ultrastructure of the Blood-Aqueous Barrier in Normal Condition and after Paracentesis
There is in the ciliary epithelium a barrier which prevents the passage of plasma proteins into the posterior chamber of the eye. The anatomical site of this blood-aqueous barrier is at the zonulae occludentes (tight junctions) located between the lateral plasma-membranes of the nonpigmented epithelial cells. Using the freeze- fracture technique we have studied these junctions in the pars plicata. As in many epithelia, they are formed by an anastomosing network of ridges on the fracture PF face and by a complementary set of furrows on the fracture EF face of plasma membranes. Features of these junctions are the presence of frequent parallel and closely associated double or triple ridges, and a few small gap junctions, associated with tight junctional elements of the zonulae occludentes. We also show that the number of junctional strands (ridges and furrows from apex to base) varies from a few strands to about 15, according to their position around the nonpigmented epithelial cells. These observations suggest that the rabbit’s ciliary epithelium is to be classified among the ‘tight’ or ‘very tight’ epithelia (Claude and Goodenough, 1973).
After paracentesis, we observed no breakdown of the zonulae occludentes. This supports the hypothesis that the site of leakage of the plasma proteins is elsewhere than ciliary epithelium.
KeywordsGlycerol Filtration Depression Syringe Glutaraldehyde
Unable to display preview. Download preview PDF.
- Davson, H.: The intraocular fluids. In: The Eye, H. Davson, ed., Vol. 1, pp. 67–186. New York-London: Academic 1969Google Scholar
- Gilula, N.B.: Development of cell junctions. Am. Zool. 13, 1109–1117 (1973)Google Scholar
- Gilula, N.B.: Junctions between cells. In: Cell communication, R.P. Cox, ed., pp. 1–29. New York: Wiley 1974Google Scholar
- Hogan, M.J., Alvarado, J.A., Weddel, J.E.: Histology of the human eye. An atlas and textbook. Philadelphia-London-Toronto: Saunders 1971Google Scholar
- Kreutziger, G.O.: Freeze-etching of intercellular junctions of mouse liver. Proc. 26th Ann. Meet. Electron Microscopical Soc. Amer., pp. 234–235, C. J. Arceneaux, ed., Baton Rouge: Claitor’s Pubi. Div. 1968Google Scholar
- Reale, E., Spitznas, M.: Freeze-fracture analysis of junctional complexes in human ciliary epithelia. Albrecht v. Graefes Arch. Ophthal. 195, 1–16 (1975)Google Scholar
- Shiose, Y.: Electron microscopic studies on blood-retinal and blood-aqueous barriers. Jap. J. Ophthal. 14, 73–87 (1970)Google Scholar