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Biomedical subjects

F C Stades

Publications and source records attributed to F C Stades.

At least 19 recordsLinked to original sources
PubMed1999

Persistent hyperplastic tunica vasculosa lentis and persistent hyaloid artery in a 2-year-old basset hound.

A 2-year-old Basset hound with unilateral persistent hyperplastic tunica vasculosa lentis and primary vitreous is described. There was leukokoria in the left eye, caused by bluish-white polar densities and haemorrhagic discoloration in the nucleus of the lens. Ultrasonographic examination of the eye revealed a small hyperechoic lens and a hyperechoic linear soft-tissue strand extending from the posterior pole of the lens through the optic disc. Power Doppler imaging revealed blood flow in this persistent hyaloid artery, but 5 months later, immediately prior to surgery, there was no flow in this artery. Ultrasonography, including Power Doppler imaging, was useful to confirm the diagnosis and to estimate the complications of surgery, especially the risk of vitreal haemorrhage after cutting of the persistent hyaloid artery. Comparison of the ultrasonographic images with those obtained by computed tomography suggested that the resolution of computed tomography is inadequate for identifying structures as fine as a persistent hyaloid artery.

Animals↗
PubMed1993

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.

Animals↗
PubMed1992

[Be wise--refer! Fact or fantasy?].

On the occasion of his retirement as an active specialist in Surgery dr. P.H.A. Poll describes the history of the development of the specialties in Veterinary Medicine in The Netherlands and carefully looks forward. As a tribute, his specialist colleagues, all related to the Companion Animal Hospital "De Wagenrenk", publish one or more case reports from there respective disciplines (ophthalmology, surgery, radiology, dermatology).

Animals↗
PubMed1991

The incidence of PHTVL/PHPV in Doberman and the results of breeding rules.

Between 1967 and 1987, in the Netherlands 3,775 Dobermans were examined for hereditary eye diseases. In 238 of these dogs severe persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV) was diagnosed. After a brief description of the clinical features the results of breeding over the recent years are discussed. The incidence (1978-1987) of severely affected dogs in the litter controls decreased from 5% to 1% in the individual controls from 19% to 8%. This is an encouraging downward tendency. Better results are to be expected once test mating and progeny-testing methods are accepted as breeding methods in dog breeding.

Animals↗
PubMed1990

Early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous. A transmission electron microscopic study.

This report provides transmission electron microscopic observations on the early pathogenesis of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV) in affected canine fetuses at days 28-44 postcoitum. The retrolental tissue by which this anomaly is characterized consists of loosely arranged fibroblasts in a randomly oriented meshwork of collagenous fibrils. Some of these cells contain melanosomes at day 44. In one day-44 eye, cells of neuroectodermal origin (Müller cells; fibrous astrocytes) were observed. From day 37 onward, the posterior subcapsular part of the lens contains rounded, increased intercellular spaces, resembling vacuoles, which deform the shape of the lens fibers. The posterior lens capsule develops normally until day 30. From day 35 onward the capsule has an amorphous ultrastructure, as opposed to the clearly laminated ultrastructure in reference eyes at day 35. In addition, the capsule's thickness increases until day 35, and, instead of growing thicker, decreases thereafter. Based on these results, it is hypothesized that a primary metabolic disorder in the lens fibers, subsequently leading to the formation of an abnormal posterior lens capsule, constitutes the primary defect in the sequence of events leading to PHTVL/PHPV.

Animals↗
PubMed1989

Early morphogenesis of the canine lens capsule, tunica vasculosa lentis posterior, and anterior vitreous body. A transmission electron microscopic study.

This study provides transmission electron microscopic observations on the early morphogenesis (from days 25-35 post coitum) of the canine posterior lens capsule, the tunica vasculosa lentis (TVL) posterior and the anterior part of the vitreous body. The presence of an anlage of the posterior lens capsule as early as day 25, recently described histologically, was confirmed by this study. In the period from day 25 to day 35, the polar part of the posterior lens capsule develops 2-29 continuous and parallel lamellae, matching 50 nm and 1.74 microns, respectively. At these early stages, the TVL consists of capillaries that are simple endothelial tubes. From day 28 onward, these can be classified as A-1-alpha capillaries according to the classification of Bennett et al. [3]. In direct proximity to the lens capsule, the vitreous body contains fibrillar material with a morphological appearance similar to that of the lens capsule. This material probably derives from both the capillary endothelial cells' basal lamina and the lens capsule. Only few cellular components were observed in the anterior vitreous body. The development of the described structures is grossly in accordance with that observed in other mammalian species. The observations presented serve as a reference for studies on the pathogenesis of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV), which is an important cause of leucocoria in children and in some dog breeds.

Animals↗
PubMed1988

Early morphogenesis of the canine lens, hyaloid system, and vitreous body.

This study deals with the early morphogenesis, from day 25 to day 35 post coitum (D25-D35), of the canine lens, lens capsule intraocular vascular system, and vitreous body. The breeding method used provides a higher accuracy as to the gestational age of the obtained fetuses than employed previously. The development of the lens, the intraocular vascular system, and the vitreous body of the dog's eye is analogous to that in other mammal species. The findings of this study, combined with data obtained from the literature, suggest that the period during which ocular development takes place is earlier in larger mammalian species than in the smaller ones. Previous descriptions of ocular development in other mammalian species, and one in the dog, reported that the development of the lens capsule starts posteriorly and proceeds towards the anterior part of the lens vesicle. In the present study, the periodic acid--Schiff positive anlage of the capsule was observed to fully surround the lens vesicle at D25, a development that is different and earlier than described previously in the dog and different from that described in other mammals. Moreover, a clear thickening of the capsule was not observed until capillaries of the tunica vasculosa lentis had reached its proximity.

Animals↗
PubMed1988

Early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous. The dog as an ontogenetic model.

Observations on (postnatal) persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV) in man and dog have been published previously. Up to the present, no evidence on the etiology of this entity was available. The hereditary occurrence of the disease in the Dobermann pinscher dog and the similarity of ocular development in mammals has provided a useful model in providing ontogenetic data. The present study deals with the early morphogenesis of PHTVL/PHPV, from day 25 to 44 post-coitum (D25-D44), in genetically affected dog fetuses. Normal beagle dog fetuses served as reference material, which has been described separately. At D30, the hyaloid system, including the tunica vasculosa lentis posterior, had developed further than in the reference fetuses. From that stage onward, a retrolental fibrovascular membrane developed. In some of the eyes of D37, posterior polar subcapsular cataracts and preretinal glial proliferations were observed. Capsular anomalies and distortions of the lens shape as seen in clinical PHTVL/PHPV were not observed, and are believed to be secondary entities. Extrapolation of some of the obtained data from dog to man is possible by the use of comparable gestational time scales. The anterior form of (PHTVL/PHPV) in man probably develops its main features in the period of approximately 43 to 66 days of pregnancy. Recently, anti-angiogenetic properties of normal vitreous have been described. This, and the fact that overdevelopment and subsequent incomplete regression of the hyaloid system plays a major role in the pathogenesis of PHTVL/PHPV, gives rise to the hypothesis that a changed amount or effectiveness of such (humoral) factors is an important factor in the etiology of this disease.

Animals↗
PubMed1987

Reconstructive eyelid surgery.

A review will be presented of some available eyelid reconstructive methods--such as the inverse triangles; and the H and rotation flap method for the correction of lid defects, e.g. after lidtumor removal. Emphasis will be put on the choice of method, handling, reconstruction and suturing of skinflaps and lid edges.

Animals↗