Localization of Fibrinolytic Activity in the Developing Rat Eye
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Abstract:
The histological localization of fibrinolytic activity in the developing eye of rat was studied by means of the histochemical fibrin slide technique. The observation that fibrinolytic activity is related to small vessels provided a means of following the developing vascularization of the eye. The hyaloid vascular system was found fully developed, together with the tunica vasculosa lentis, at the 18th day of intrauterine life. Involution of these vessels begins between the third and the seventh day after birth. The retinal vessels begin to develop between the 16th and the 18th day of intrauterine life. The choroid acquires fibrinolytically active vessels in the second week of life. At this time also the ciliary body becomes vascularized. The patterns of appearance and disappearance of sites of fibrinolytic activity observed during the development of the eye are related to the functional morphology of the involved tissues.Keywords:
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Involution (esoterism)
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The scleral attachments of the ciliary body and choroid were found to be densest from the equator to the posterior pole, less dense at the ora serrata, and practically nonexistent under the ciliary body and between the ora and equator. The elasticity of the choroid is such that in the excised human eye about 2 mm. Hg pressure is necessary to distend the uvea against the sclera. The tensile strength of the choroid was found to be greater than 5 Gin. per centimeter. It was concluded that although the interciliary zomdes are under stress in vivo the elastic behavior of the ciliary body could not be entirely attributed to these zomdes. It is suggested that, since pressure in the suprachoroidal space is lower than intraocular pressure due to the elasticity of ciliary body and choroid, in the presence of ocular hypotony the suprachoroidal pressure may fall below atmospheric pressure, encouraging transudation into the space. The distribution of the transudate is explained by the distribution of the suprachoroidal lamellae.
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Uvea
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The uveal tract consists of three parts: iris, ciliary body and choroid. Iris is the colored part of the eye, which makes the pupil regulate the light rays. The ciliary body consists of a ring of muscles tissue that changes the shape of the lens and secretes the clear fluid (aqueous humor) that fills the inside of the eye (anterior segment). And the choroid tissue is thin filled with blood vessels that are part of the middle layer of the eye ball between the sclera (white outer layer of the eye) and the retina (the inner layer of nerve tissue at the back of the eye). The choroid is a layer of blood vessels and connective tissue that lines the back of the eye and supplies nutrients to the retina. Together, these three structures make up the uveal tract and play important roles in the anatomy and function of the eye. This book chapter will explain about the Uveal anatomy and Physiology, its understanding.
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The presence of atrial natriuretic factor (ANF) in choroid, retina and ciliary body of rabbit eyes has been studied. The peptide was extracted by reverse phase chromatography using Sep-Pak C18 cartridges. Immunoreactive ANF (Ir-ANF) was measured by a specific RIA. In the choroid, retina and ciliary body the ir-ANF concentrations were 444 +/- 94, 67 +/- 12 and 223 +/- 75 pg/g tissue weight (n = 16), respectively. The biological activity of the acid extract ANF was evaluated by a 125I-ANF binding assay to a retinal particulate preparation. Results demonstrate the existence of biological active ANF in choroid, retina and ciliary body of rabbit eyes. The presence of ANF and its specific receptors in the ocular tissues suggests that this hormone might play a physiological role in the intraocular fluid homeostasis.
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To review the ocular retention rates, visual results, and metastases in uveal tumours managed with eye wall resection techniques.This was a retrospective analysis of consecutive local uveal tumour resections performed by a single surgeon. All enucleation specimens were reviewed by one author. Both parametric and non-parametric analysis of data were performed.138 eyes were scheduled for eye wall resection surgery. The mean age was 52 years (range 11-86 years). Tumours involved predominantly the iris in 14 cases, iris-ciliary body in 57, ciliary body alone in 18 patients, and in 49 cases the choroid was involved (ciliochoroidal, iris-ciliary body-choroid, or choroid). 125 eyes harboured melanomas; posterior tumours were more likely to have epithelioid cells (p<0.05). The mean follow up was 6 years. The mean clock hours in iris and iris-ciliary body tumours was 3.5. In tumours that involved the choroid the mean largest diameter was 12.9 mm and the mean thickness 8.5 mm. 105 of 138 (76%) eyes were retained. Histological assessment of surgical margins did not correlate evidence of tumour in enucleated eyes or metastatic disease. Surgical margins of more anterior tumours were more likely to be clear on histological evaluation (p<0.05). Approximately 53% of retained eyes had a final visual acuity of > or =20/40; visual results were significantly better in more anteriorly located tumours (p<0.05). All retained iris tumour cases had > or =20/40 final visual acuity. In tumours that involved the choroid nine of 31 retained eyes kept that level of visual acuity. Eight patients developed metastases; all metastatic events developed in patients with tumours that involved the choroid, and seven of eight were mixed cell melanomas.76% of eyes were retained and 53% of these had a final visual acuity of > or =20/40. Only 7% of uveal melanoma patients developed metastatic disease with a mean follow up of 6 years. Survival did not appear to be compromised with eye wall resection and in very thick, more posterior melanomas it appeared that ocular retention and visual results were better than with radiation alone.
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Although metastases from malignant melanomas of the ciliary body and choroid are common, similar tumors from the iris are rare. In this article seven such cases are described. They represent 3.5% of 196 cases in our files that were followed up for a minimum of five years where the tumor was confined to the iris and did not involve the ciliary body or the choroid. To our knowledge, this is the largest series to be described in the literature. Of the seven patients who died of metastases, six were male and autopsies were performed on four. There is evidence that diffusely infiltrating, heavily pigmented tumors, and tumors whose cell nuclei show prominent nucleoli are those most likely to metastasize.
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Radioligand
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The present study was designed to demonstrate the comparative anatomical, histological study of Uvea in the eyes of two cyprinid fresh water teleost fishs Garra rufa (first species) and Chondrostoma regius (second species). Which belong to family Cyprinidae Each species differ in light intensity, in that G. rufa bottom dwelling but C. regius approximately surface dwelling. The two species omnivorous in nutritional nature. The choroid in the two species, essentially similar in that it composed of connective tissue consist of fibers, melanocytes, sinusoid, blood vessels and nerves. On the other hand, variations appeared in the thickness and nature of these components, but the choroid was more developed in C. regius. The distinct structures in the choroids of the two species were tapetum lucidum and argenteum layer which were more developed in C. regius. On the other hand there were variations in chotoid components intraocularly for each species. The choroid gland appeared at both sides of optic nerve in the choroid, and more developed in C. regius. The most important result in this study was the appearance of choroid fissure and falciform process in the eye of G. ruffa only. The ciliary body disappear in both species, but its position called ciliary region which was distinct in the eye of both species. The ciliary region extended between the retina and iris which composed of two portions, the first one originated from the choroid and the other from the retina. The length of ciliary region differs between the two species as well as intraocularly. The iris showed a wide variations in the shape, thickness, length and nature of its components between the two species and intraocularly. The iris components have two origins. The first one from the choroid (iris stroma), the second from the retina which were the non pigmented ciliary cells and pigmented epithelium.We can conclude that the presence of tapetum lucidum ,argenteum layer,Choroid glands in the Choroid of both species indicate that they posses high visual acuity ,high resolution power and strong image contrast but G. ruffa have more visual power because the appearance of Chroid fissure and falciform process.
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The authors describe a 62-year-old man with a malignant nonteratoid malignant medulloepithelioma of the ciliary body with extension into the anterior choroid and posterior chamber. He developed gradual loss of vision in his right eye, and a clinical diagnosis of malignant melanoma of the ciliary body and choroid was made.Histopathologic examination of the enucleated eye showed a malignant nonteratoid medulloepithelioma of the ciliary body with extension into the anterior choroid and posterior chamber.This report provides clinicopathologic evidence that intraocular medulloepithelioma can occur rarely in an adult. The lesion clinically may mimic a malignant melanoma. The authors also summarize five previously reported cases of this unusual lesion.
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