The Demonstration of a Blood-Ocular Barrier in the Albino Rat by Means of the Intravitam Deposition of Silver

Abstract

Silver nitrate administered to rats in their drinking water from 6 months to a year or more, results in generalized argyria (1). I n the central nervous system, the intravitam deposition of the silver, as revealed by histological and electron microscopical examinations (Wislocki and Leduc, (2); Dempsey and Wislocki, (3)), approximates the pattern of the hematoencephalic barrier.I n the further course of examining silver-treated albino rats, we have noriced that silver accumulates mainly in two regions of the eyes, namely, in the basement membranes of the ciliary processes and in Bruch's basal membrane between the retinal epithelium and the choriocapillary layer of the chorioid membrane. Silver also accumulates in traces, visible only with the electron microscope, in the basement membranes of the retinal capillaries. We regard the deposition of silver in these sites as manifestations of a bloodocular barrier.The purpose of this paper is to describe the deposition of silver in the several regions of the blood-ocular barrier of the albino rat, as revealed by histological examination and by the electron microscope. I n the discussion, the blood-ocular barrier will be compared with the hematoencephalic barrier. Materials and MethodsThe eyes of 4 male albino rats of the Sprague-Dawley strain, which had received 0.15 per cent silver nitrate in their drinking water for 10 and 13 months and had been maintained on a standard purina chow diet, formed the subjects of this investigation. At autopsy the eyes were excised and cut open in the equatorial plane and the lenses were removed. For histological study the anterior and posterior halves of the eyes were placed in Orth's fixative. The specimens were dehydrated, embedded in paraffau, and 5/~ sections were cut. The deparaflfinized sections were stained by the periodic acid-Schiff method and some were counterstained with Ehrllch's hematoxylin. Some of the sections were exposed to saliva for

Ocular argyrosis secondary to long-term ingestion of silver nitrate salts

“…However, a previous histopathologic study in albino rats did not show any accumulation of silver deposits in RPE cells,10 and furthermore, the fundus autofluorescence images from our patient did not show any signs of RPE damage. To our knowledge, there is only one previous report describing choroidal and retinal changes in patients with ocular argyrosis by means of fundus photographs and fluorescein angiography 9.…”

“…Wislocki and Ladman conducted an experiment in albino rats involving giving them water containing silver nitrate for a period of 6 months to a year and trying to demonstrate the blood-ocular barrier. They reported histopathologic data showing that silver accumulated in two regions of the eye, ie, the ciliary processes and Bruch’s membrane 10. They also noted that the longer silver nitrate was administered, the greater the amount that accumulated.…”

Ultrastructural morphology and protein content of the internal organic material of rat otoconia

“…Research efforts to identify the organic material within the otoconial membrane histochemically have yielded various results. Some authors have shown the presence of glycoprotein based on periodic acid Schiff (PAS) staining (Wislocki and Ladman, 1955;Belanger, 1960;Igarashi and Alford, 1969;Ross, 1973). Belanger (1953Belanger ( , 1956Belanger ( , 1960 using iron adsorption and metachromatic staining with toluidine blue, indicated the presence of glycosaminoglycan which may (Belanger, 1960) or may not (Vilstrup and Jensen, 1954) be sulfated.…”

“…In mammals, the mineral is calcium carbonate in the form of calcite. The precise composition of the organic phase is unknown, but it consists of protein and carbohydrate according to results from histochemical (Wislocki and Ladman, 1955;Belanger, 1960) and biochemical studies (Ross and Pote, 1984;Ross et al, 1985;Gil-Loyzaga et al, 1985).…”

Studies on the Structure of the Vitreous Body

“…In adult animals, vital staining and phagocytosis can be observed only after the administration of very large doses or after injury to the eye, such as puncture of the anterior chamber (Schnaudigel, 1913;Hamburg, 1957). This is probably due to the development of the hemato-ocular bar¬ rier in the adult animal (Towbin, 1933;Wislocki and Ladman, 1955). Injection of colloidal material into the vitreous body results in phagocytosis, accompanied by an increase in the number of cells in the vitreous body as a result of cellular infil¬ tration (Potiechin, 1878;Gray, 1933;Ham¬ burg, 1957).…”