No abstract

These vascular changes that are associated with colobomatous anomalies may impede the retinal circulation and be responsible for the fluctuating fluorescein pattern during fluorangiogram of affected animals. The lesions of the vascular wall may increase the subretinal fluid due to the leakage of fluid, thus causing the maculopathy or serous retinopathy, which is frequently associated with posterior pole coloboma.

Rupture of the posterior lens capsule with extrusion of lens fibers or entire lens cortex Rats with the plaques were euthanized by exsanguination under ether anesthesia for further examination.The posterior of the lens was examined under a dissecting microscope, and the plaques were composed of hemispherical aggregates on the capsule near the posterior pole of the lens (Fig. 2). The lens and vitreous were otherwise normal. The eyeballs were fixed in a combined fixative of 1°7o formaldehyde and 1.5% glutaraldehyde, embedded in paraffin, cut at 5 /-1m, and stained with hematoxylin and eosin for microscopic examination.Histologically, the lens fibers were swollen and extended into the vitreous (Fig. 3). A few mononuclear and multinucleated giant cells were occasionally associated with the site of rupture. However, there was no other inflammatory response. The plaques observed consisted of the clusters of swollen lens fibers within the vitreous, and the central white foci were sites of ruptured lens. The swollen lens fibers were basophilic in contrast to the unaffected fibers beneath the capsule which were eosinophilic and in parallel arrangement.In 2 males older than 104 wk, the entire lens extruded posteriorly into the vitreous. The edge of the lens capsule was coiled at the equator (Fig. 4). This lesion likely represents the most severe and the end stage of the posterior lens runture. There was minimal inflammatorv resdonse.

Abstract:Focal chorioretinal atrophy observed in untreated Sprague-Dawley

In order to investigate the effect of soft X-ray irradiation on ocular development, pregnant rats were exposed to a single 12.5 Gy irradiation on embryonic day 9 (ED 9). The embryos obtained by laparotomy on ED 12 and 21 were examined for ocular abnormalities under a binocular stereo-microscope and a light microscope. The ED 12 embryos were stained with osmium tetroxide to facilitate the observation. The stereo-microscopic examination on ED 12 and 21 revealed various types of ocular abnormalities characterized primarily by aplasia or hypoplasia of the optic cup and invaginated lens placode. The light microscopic examination further confirmed these findings histomorphologically, and the hypoplastic abnormalities were classified into three types: (1) hypoplasia of the optic cup and invaginated lens placode, (2) complete malformation of the optic cup and hypoplasia of the invaginated lens placode, and (3) complete malformation of the optic cup and invaginated lens placode. Because the lens was formed in the complete absence of the retina, the development and differentiation of the retina and lens do not seem to be tightly synchronized. Thus, this sequential analysis on ocular abnormalities during the early stage of development supports the notion that the presence of the retina is not always necessary for the development of the lens.