Effects of duration and intensity of illumination on several parameters of the chick eye

Effects of duration and intensity of illumination on eye weight, eye diameter, corneal diameter and anterior chamber depth were investigated in Warren chicks. Increase in eye weight was observed in continuous light, LD 22:2 and continuous darkness. Shallow anterior chamber and small corneal diameter were observed in continuous light and LD 22:2, but not in continuous darkness. Continuous bright light (5000 lux) did not induce an increase in the eye weight but instead induced severe lesions in the anterior segment of the eye. Injection of corticosterone (500 micrograms) induced a significant reduction in the eye weight.     

Structure of the eye of Haideotriton wallacei, a North American troglobitic salamander

The eye of Haideotriton wallacei is more reduced histologically than those of othe troglobitic salamanders. The tiny eye is imbedded in a mass of adipose tissue. No extrinsic eye muscles are present. A rudimentary lens is present in about half of the eyes examined. In two instances the lens is surrounded by a small chamber; most eyes lack a chamber. The retina and iris are relatively undifferentiated. The relatively massive retina lacks rods and cones, an outer plexiform layer and subdivided nuclear layers. A tiny optic nerve runs to the brain.     

Relationships between Presence of the Eye Cup and Maintenance of Lens-Forming Capacity in Larval Xenopus laevis

The lentectomized eye of larval Xenopus laevis can regenerate a lens by a process of lens-transdifferentiation of the cornea and pericorneal epidermis. These tissues can form the lens only when they become in direct communication with the environment of the vitreous chamber (neural retina) indicating that the eye cup plays a fundamental role in this process.
In this work the role of the eye cup in the maintainance of the lens-forming capacity of the cornea and pericorneal epidermis was studied by allowing these tissues to cover the enucleated orbit for different periods, and then implanting them into the vitreous chamber of the contralateral eye. Under these experimental conditions the maintainance of the lens-forming capacity of the cornea and pericorneal epidermis showed no significant correlation with the time from enucleation to implantation.     

Noninvasive high-resolution in vivo imaging of cell biology in the anterior chamber of the mouse eye

There is clearly a demand for an experimental platform that enables cell biology to be studied in intact vascularized and innervated tissue in vivo. This platform should allow observations of cells noninvasively and longitudinally at single-cell resolution. For this purpose, we use the anterior chamber of the mouse eye in combination with laser scanning microscopy (LSM). Tissue transplanted to the anterior chamber of the eye is rapidly vascularized, innervated and regains function. After transplantation, LSM through the cornea allows repetitive and noninvasive in vivo imaging at cellular resolution. Morphology, vascularization, cell function and cell survival are monitored longitudinally using fluorescent proteins and dyes. We have used this system to study pancreatic islets, but the platform can easily be adapted for studying a variety of tissues and additional biological parameters. Transplantation to the anterior chamber of the eye takes 25 min, and in vivo imaging 1-5 h, depending on the features monitored.     

Implantation of embryonic pancreas into the anterior chamber of healthy and diabetic rats

The possibility of pancreatic-islet embryonic implantation into the frontal chamber of the eye in Wistar rats has been demonstrated. The implantation was followed by the induction of alloxan diabetes. Clinical diabetic compensation has been shown in a number of experimental animals (maximum time of experiments--45 days). The formation of islet-like structures in the frontal chamber of the eye was confirmed microscopically. The structures contained B cells in their cytoplasm. Cellular differentiation leading to the appearance of functionally active endocrine cells has been noted in the implants.     

Experimental data on the penetration of gentamicin into the media of the eye]

Penetration of Soviet gentamicin into the humor of the anterior chamber and vitreous body of the eye with aseptic inflammation was studied after the antibiotic administration by various routed, i.e. instillations of 8 per cent antibiotic solution and 8 per cent antibiotic solution methylcellulose into the conjunctival sac, injections of 20 mg of gentamicin subconjunctivally and retrobulbarly, injections of gentamicin intramuscularly in doses of 0.6 mg/kg. The studies showed that gentamicin penetrated into the humor of the anterior chamber and vitreous body of the eye after all the administration routes mentioned above in concentrations sufficient for the antibiotic antimicrobial effect and persisted in the eye media for prolong periods of time (24--48 hours). The highest concentrations of the antibiotic in the tumor of the anterior chamber were achieved after its administration subconjunctivally or after instillation of its 8 per cent on methylcellulose, while in the vitreous body its highest concentrations were achieved after injections subconjunctively, retrobulbarly or intramuscularly. Instillations of gentamicin solution on methylcellulose provided higher and more persistant concentrations of the antibiotic in the humor as compared to instillations of its aqueous solutions. Retrobulbar injections of gentamicin had no advantages as compared to subconjunctival administration with respect to providing higher concentrations of the antibiotic in the eye media.     

Immune response to immunization via the anterior chamber of the eye. II. An analysis of F1 lymphocyte-induced immune deviation

Exposure to alloantigen via the anterior chamber of the eye elicits a transient suppression of cellular immunity, whereas humoral immunity is preserved--i.e. F1 LI-ID. The majority of lymphoid cells inoculated into the anterior chamber are retained within the posterior segment of the eye. The latter serves as a depot of alloantigen, allowing the chronic egress of small numbers of cells into the vascular tree. The persistence of this antigen depot is essential to the development of F1 LI-ID. Since there is a preferential distribution of cells that migrate from the eye to the spleen, the functional integrity of the latter is also necessary to elicit F1 LI-ID. It is concluded that an anatomically intact spleen, i.v. presentation of antigen, and persistence of antigen within the eye are all important to the elicitation of this phenomenon.     

Transdifferentiation of eye tissues in anuran amphibians: Analysis of the transdifferentiation capacity of the iris of Xenopus laevis larvae

Abstract. Lensectomized Xenopus laevis larvae are capable of regenerating a lens from the cells of the outer cornea. Unlike the outer cornea, the iris of larval Xenopus exhibits a high degree of phenotypic stability, even when it has been damaged to various degrees in order to stimulate its latent transdifferentiative competence. However, when isolated from its surrounding tissues and implanted in an appropriate site, the dorsal iris of larval Xenopus is capable of following a differentiative pathway different to that normally followed in situ. Our results show that, when such an implant is placed in the vitreous chamber of a lensectomized eye, the pigmented epithelial cells of the iris transdifferentiate into neural retina regardless of whether the iris stroma is present or not. Unlike the vitreous chamber, the environment of the anterior chamber of a lensectomized eye does not promote the transdifferentiative process of the iris. We suggest the existence of eye factors that promote retina-forming transformation of the iris and that are distributed in a gradient in lensectomized eyes.     

Effect of ectopic transplantations on the cytological structure of mouse rhabdomyosarcomas]

12 mouse rhabdomyosarcomas from V--XI transplant generations were investigated at their growing in the anterior chamber of the eye, in the testis, lungs and subcutaneous fibrous tissue. With these modes of transplantation rhabdomyosarcomas were seen differentiating to different levels and differed in their cell populations. The most differentiated rhabdomyosarcomas were in the anterior chamber of the eye: they formed myotubes with cross-striated myofibrilles; the least differentiated ones occurring in lungs. Rhabdomyosarcomas, inoculated in testes, intensively dessiminated in the lymph-nodes and in the organs of abdomen. It is concluded that the degree of tumor autonomy depends on the tumor--organism interactions.     

Hypoxia as pathogenic factor affecting the eye tissues: The selective apoptotic damage of the conjunctiva and anterior epithelium of the cornea

The effect of acute hypoxia on the occurrence of apoptosis in eye cells in rats placed in a pressure chamber was studied. Selective primary lesion of cells of the conjunctiva and the anterior corneal epithelium was found. A possible role of the simulated hypoxic conditions in the dry eye syndrome pathogenesis, which is accompanied by primary lesion of cells in the anterior eye surface tissues is discussed.     

The role of cytokines in the regulation of ocular autoimmune inflammation

The eye is a unique place for the development of an immune response. Beyond the usual mechanisms of immune restraint, the eye evolved with its exclusive mechanisms such as anterior chamber associated immune deviation. Therefore, immune-mediated inflammation in the eye does not develop at the same pace as in other sites of the body. Here we will address such peculiarities as they regard to ocular autoimmunity, using the experimental autoimmune uveitis as a model to understand the participation of cytokines in the process of aggression against the eye, as well as their immunoregulatory role.     

Clinostomum attenuatum (Digenea) from the eye of Bufo marinus

Two specimens of the cane toad, Bufo marinus, were found with single worm infestations of the eye. One worm was excysted in the eye chamber, the other still encysted in the choroid layer; both worms were identified as Clinostomum attenuatum. This finding is both a new host record and a new site of development for this amphibian parasite.     

Mathematical model of flow in the vitreous humor induced by saccadic eye rotations: effect of geometry

Saccadic eye rotations induce a flow in the vitreous humor of the eye. Any such flow is likely to have a significant influence on the dispersion of drugs injected into the vitreous chamber. The shape of this chamber deviates from a perfect sphere by up to 10–20% of the radius, which is predominantly due to an indentation caused by the lens. In this paper we investigate theoretically the effect of the domain shape upon the flow field generated by saccades by considering an idealized model. The posterior chamber geometry is assumed to be a sphere with a small indentation, undergoing prescribed small-amplitude sinusoidal torsional oscillations, and, as an initial step towards understanding the problem, we treat the vitreous humor as a Newtonian fluid filling the chamber. The latter assumption applies best in the case of a liquefied vitreous or a tamponade fluid introduced in the vitreous chamber after vitrectomy. We find the flow field in terms of vector spherical harmonics, focusing on the deviation from the flow that would be obtained in a perfect sphere. The flow induced by the departure of the domain geometry from the spherical shape has an oscillating component at leading order and a smaller-amplitude steady streaming flow. The oscillating component includes a circulation cell formed every half-period, which migrates from the indentation towards the center of the domain where it disappears. The steady component has two counter-rotating circulations in the anterior part of the domain. These findings are in good qualitative agreement with the experimental results of Stocchino et al. (Phys Med Biol 52:2021–2034, 2007). Our results predict a significant reduction in the expected time for drug dispersal across the eye compared with the situation in which there is no fluid flow present.     

Matrices containing glycosaminoglycans in the developing anterior chambers of chick and Xenopus embryonic eyes.

The fibrous matrix present in the anterior chamber of the chick eye on the 4th day of development has been shown by autoradiography and histochemistry to contain chondroitin sulfate, protein, neutral polysaccharides, and possibly hyaluronic acid (HA). Its synthesis, probably by the mesenchyme of the angle of the eye, is completed by around 10 days of development. In the scanning electron microscope (SEM) it can be seen that, although the matrix thins as the eye grows, it does not disappear until the 15th day. The development of the Xenopus cornea is described; this animal has a matrix in its anterior chamber from soon after the formation of the inner cornea (stage 41) until metamorphosis 7 weeks later. In the SEM, this material appears as a dense, featureless aggregate rather than as a matrix of thick fibres; in the transmission electron microscope, it is seen to be a network of fine filaments containing small dark-staining granules. Histochemistry shows that it contains HA, protein, and neutral polysaccharides. The morphological evidence is compatible with the matrix being made by the inner cornea. The probable major role of the matrix is to separate lens from cornea in establishing the anterior chamber. In the chick embryo, at least, the matrix is also likely to help stabilise the endothelium during its formation.     

慢性高眼压下兔视网膜组织蛋白质组变化的初步研究

应用蛋白质组学技术对兔青光眼慢性高眼压视网膜组织的蛋白进行初步分析。左眼前房注入0.2mL复方卡波姆溶液制作成慢性高眼压模型,右眼为对照眼。28d后分离各组视网膜组织,用双向电泳分离试验组和对照组的蛋白,然后分析电泳图谱,对比、分析其表达蛋白质点的差异,寻找兔视网膜中与慢性高眼压相关的蛋白质。结果表明,慢性高眼压诱导视网膜组织3种蛋白质出现明显差异表达。质谱鉴定出3个蛋白质,分别为热休克蛋白70(heat shock 70 kD protein,HSP70),丙酮酸激酶(Pyruvate kinase)和烯醇酶(enolase)。通过双向电泳,发现兔视网膜蛋白质表达与对照眼相比有质和量的变化,这些变化涉及与神经节细胞(retinal ganglion cells,RGCs)糖酵解及应激反应有关的几组蛋白质,提示上述蛋白质组改变可能参与了慢性青光眼神经节细胞凋亡的过程。     

Posterior microphthalmia and nanophthalmia in Tunisia caused by a founder c.1059_1066insC mutation of the PRSS56 gene

Congenital microphthalmia (CMIC) is a common developmental ocular disorder characterized by a small, and sometimes malformed, eye. Posterior microphthalmia (PM) and nanophthalmia are two rare subtypes of isolated CMIC characterized by extreme hyperopia due to short axial length and elevated lens/eye volume ratio. While nanophthalmia is associated with a reduced size in both anterior and posterior segments, PM involves a normal-size anterior chamber but a small posterior segment.     

The Hammer and the Eye: Beware

In reporting this small series of foreign-body injuries to the eye it is emphasized how normal an eye may appear and yet have a foreign body lurking in its anterior chamber. The patient''s account of the injury may be very deceptive and an x-ray picture of the eye must be taken if a foreign body is even remotely suspected, particularly if a hammer is mentioned. Prompt diagnosis followed by well executed surgery leads to good results in these cases.     

Supramolecular changes in preserved corneal tissue exposed to alpha-tocopherol]

Kinetics of chemifluorescence of the tissue of the cornea of isolated dog eyes (induced by 1% hydrogen peroxide) was confronted to the results of determination of the ultrastructural changes in the 30th day the eye preservation in a moist chamber at 4 degrees C with and without replacement of the chamber humour of the eye with alpha-tocopherol. The results of investigations pointed to profound changes of free radical processes in the structural components of the corneal cells with changes in the periods and conditions of preservation. It is supposed that these disturbances underlied the trigger mechanisms of the autolysis. Stabilization of the lipoprotein complexes of the cell in preservation is apparently determined by the capacity of antioxidants, particularly of alpha-tocopherol to maintain oxidative processes at a constant level.     

Visual-optical characteristics of caged and semifree-ranging monkeys

Five species of macaques and one species of mangabey comprising a total of 324 monkeys (132 males and 192 females) were given visual examinations which included measures of corneal curvature, depth of the anterior chamber, thickness of the lens, depth of the vitreous chamber, total axial length, total power of the eye and intraocular pressure as well as the refractive error of eye under cycloplegia in the anesthetized monkey. Cercocebus and Macaca mulatta demonstrated the greatest amount of myopia and Macaca fascicularis the least, with M. speciosa, M. fuscata, and M. nemestrina in order between these extremes. The M. nemestrina eye approximates that of the chimpanzee in size and relationship of the components. The findings indicate that males have larger eyes than females, the curvature of the cornea decreases as the axial length increases, and there is a close relationship between the length of the eye and the amount of myopic refractive error. There is some evidence that amount of myopia and the percentage of animals showing a myopic refractive error are related to the visual conditions and the behavior patterns of the different species.     

Inhibition of Lens Regeneration by Nickel Subsulfide in the Japanese Common Newt, Cynops pyrrhogaster

To investigate the effects of nickel subsulfide (Ni₃S₂) on lens regeneration, Ni₃S₂ was administered to the lentectomized newt eye by a single injection into the eye chamber. Lens regeneration was inhibited in the early stage of regeneration with about 60% of the treated eyes after 25 days, while all control eyes had a regenerating lens. The size of the regenerating lens in the treated eyes was the same as in controls. Lens regeneration was inhibited in all treated eyes containing Ni₃S₂ particles within the eye chamber. Inhibition of lens regeneration in the treated eyes was about 80% at 3 months, when all control eyes had already completed lens regeneration. Although the tendency toward pupil disappearance was prominent in the eyes having no regenerating lens, there were also a few eyes which had no regenerating lens and no signs of pupil disappearance. The significance of these results was discussed in relation to the regeneration and carcinogenesis.