Early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV). Scanning electron microscopic observations.

This study provides scanning electron microscopic observations on the early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV) in canine fetuses at days 28 35 postcoitum (D28 and D35). From previous studies regarding PHTVL/PHPV it is known that a retrolental plaque of fibrovascular tissue is present in eyes of affected canine fetuses from the D33 stage. The contribution of vitreous cells to the formation of the plaque is supported by the results of this study. The lens capsules at the stages described were not found to contain abnormalities such as transparent (thinner) parts or rents, as have been described for postnatal cases of PHTVL/PHPV. These findings support the hypothesis that the capsular anomalies observed in postnatal patients are secondary entities.

A comparison between three brands of 10.0 nylon sutures.

10.0 nylon sutures from three different manufacturers were compared on the basis of the scanning electron microscopic aspect, the maximum tensile strength of the thread and the maximum tensile strength of the knot (single throw). Scanning electron microscopy revealed identical surface characteristics and identical diameters (approximately 30 micrometers) for all threads. Threads which had been pulled on became wavy and showed markedly thinned and flattened segments. Maximum tensile strength was measured by a simple device, which is described. The maximum tensile strength of the thread varied considerably between the three brands (from 31.3 gr, S.D. 2.0 gr, to 46.2 gr, S.D. 3.7 gr.) The maximum tensile strength of the knot (single throw) was approximately the same for all three (ranging from 25.9 gr, S.D. 4.1 gr to 28.2 gr, S.D. 2.6 gr).

Free running Neodymium-YAG laser coagulation of the human fovea. A light and electron microscopic study.

Free Running Neodymium-Yttrium Aluminum Garnet (FR Nd-YAG) laser coagulation of the macula was performed in seven human eyes. Follow-up varied from 1 to 15 days. Damage to the outer retinal layers was apparent immediately after exposure whilst that in the inner retinal layers developed subsequently. The choriocapillaris and major choroidal vessels were occluded. Visual acuity changed in an unpredictable way.

The ring of Soemmerring in man: an ultrastructural study.

The ultrastructure of lens remnants is described and illustrated after extracapsular cataract extraction in 11 pseudophakic human eyes, using scanning and transmission electron microscopy. The retained lens material formed a ringlike structure that was enclosed by the posterior and anterior capsule, as described extensively in the literature, and was found to contain dividing and differentiating epithelium. Both normal and degenerating subcapsular lenticular fibers and a central cataractous region were found. The sealing of the anterior capsular flap to the posterior capsule, although rather tight, had failed to prevent epithelial cells from escaping the ring in 9 out of 11 cases. Inflammatory cells near this sealing place and in the ring were found in all three specimens examined by transmission electron microscopy.

Cytology of human intraocular lenses. A scanning electron microscopic study.

Scanning electron microscopy of 9 intraocular lenses, removed from patients mainly because of corneal problems, revealed the presence of different types of adhering elements. Independent of clinically significant symptoms of infection, macrophages and/or epitheloid cells and/or granulocytes were observed. On their anterior surface, 3 lenses showed flat cells or cellular remains which are supposed to represent corneal epithelial cells. Membrane fragments were found on 3 other lenses. Most of the polymethylmethacrylate optics of the lenses showed some deformation and/or cracking and to evaluate them some additional studies with new intraocular lenses were performed. High pressure during the preparation procedure for scanning electron microscopy was found to be the cause.

The ring of Soemmerring in the rabbit: A scanning electron microscopic study.

The scanning ultrastructure of the remnants of the lens left in the eye after extracapsular lens extraction was investigated in the rabbit. Extracapsular lens extraction was performed in 25 eyes and the development of after-cataract followed by biomicroscopic examination. After survival times varying between 1 week and 12 months, the eyes were enucleated and the rings of Soemmerring treated for light microscopy and transmission and scanning electron microscopy. Soemmerring's ring consisted of the fused remnants of the dissected anterior and posterior lens capsule, enclosing the equatorial part of the former lens, left behind after the operation. The anterior capsule and, to a lesser extent, also the posterior capsule were multilayered and appeared to be thickened. While the remnant of the anterior capsule was lined by a monolayer of epithelial cells, the posterior part of the capsule was only partly lined by irregularly arranged epithelial cells. All epithelial cells were highly vacuolized. In transection the interior part of the ring consisted of normal fibers, irregularly oriented and irregularly shaped fibers, degenerated fibers, and globular amorphous masses. Many of the normal fibers contained cell nuclei. At the equator and at the posterior side of the fusing anterior and posterior capsule as well, the fiber organization resembled the lens bow region of normal lenses. Frequently, islands of epithelial cells were observed in the center of the ring. The vitreal face of the posterior capsule in the center of the ring (in the optic axis of the eye) seemed to be unchanged and on its pupillary surface, fibers of different size as well as fibroblastlike cells were found. However, clear-cut Elschnig's pearls were absent. Our results are compared with the observations summarized in the literature. It can be concluded that the epithelial cells in Soemmerring's ring retain their capacity for division and differentiation. The newly formed fibers seem to be pushed to the center of the ring and to degenerate.