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Study of Lens Regeneration By Cytolysed Iris Implants Under
The Influence of Vitamin A in Froglets of Rana
Cynophlyctis |
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| Paper Id :
19346 Submission Date :
2024-10-12 Acceptance Date :
2024-10-23 Publication Date :
2024-10-25
This is an open-access research paper/article distributed under the terms of the Creative Commons Attribution 4.0 International, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. DOI:10.5281/zenodo.14185351 For verification of this paper, please visit on
http://www.socialresearchfoundation.com/resonance.php#8
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| Abstract |
Regeneration is a developmental process in which the lost Part of an organ is restored. This research Paper includes the result of Experiment made to study of lens regeneration by Cytolysed iris implants under the influence of vitamin A in froglet Stage of indian Skipper frog Rana cynophlyctis. The Experiment was completed in a series where animals were divided in to 2 groups, A and B after their lentectomy. In the animals of group A cytolysed iris and retinal tissue were implanted but were not treated with vitamin A it was found that only in 10%. Cases unidentified. Structures developed. In the animals of group B treatment of vitamin A was given after the implantation of cytolysed iris and bit part of retinal tissues. It was observed that regeneration had occurred in 96.7% Cases, out of which double lenses developed in a 60%. Cases, fused lenses in 16.7%Cases While 20%. Cases Showed single regenerated lens. |
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| Keywords | Regeneration, Rana Cynophlyctis, Froglets, Lens, Lentectomy Vitamin A, Cytolysed Iris Implants, Double Lenses. | ||||||
| Introduction | Regeneration is a developmental process in which the lost part of an organ is restored, it involves all those fundamental process including cell proliferation Cell movement, morphogenesis, histogenesis and growth which occur during ontogenetic development in the Embryonic Stage. In Amphibia ability of regeneration in anura is restricted to their larval period only as the tadpoles grow and metamorphic Changes are initiated the ability to regenerate gradually decline and in most of the anurans it finally disapears before metamorphic climax. The lens regeneration in eye starts from dorsal rim of the iris. During this process trane formation of iris into lens starts with depigmentatio followed by multiplication of iris cells.Later these cells are arranged to form vesicle. Subsiquently the cells in the posterior Wall of Vesicle differentiated into Lens fibres and finally a new lens is formed. A factor Controlling the differentiated state of the cells is found to be in the dorsal iris. Removal of this factor by Somehow leads to the initiation of lens regeneration. In previous studies Vitamin A was found to be Very important Chemical which removes the many restriction and enhanced the extent of differentiation of cellsand thus accelerate lens regeneration in maturetadpoles. In view of the above present investigation were wider Undertaken, to study the effect of vitamin A on lens regeneration in the froglet of Rana cynophlyctis. Jangir et al (1995, 1997), Shekhawat (1998, 1999), Jangir (200) and Ojha (2000) were studied that Vitamin A accelerates lens regeneration in Amphibian tadpoles and chick Embryes These Studies on Effect of vitamin A on lens regeneration Suggested the need to investigate whether dorsal iris or cytolysed iris implants could regenerate the lens under the influence of vitamin A. For this purpose iris and bit Part of retina was removed from the donors denucleated eye and homogenized the complete tissue in saline Water. Then this cytolysed tissue Extract was transplanted- auto plastically in the denucleated eye of froglet and Study were made about the influence of Vitamin A on lens regeneration from iris and cytolysed iris tissue. |
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| Objective of study | The significance of the above work is to provede evidence
using denuclationon and recombination techniques in vitro that treatment of
vitamin A result in formation of lens from dorsal iris and cytolysed iris
tissue in froglets of Rana cynophlychics. |
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| Review of Literature |
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| Methodology | For Experiment froglets of Rana cynophlyctis employed wereof the same age at the time of operation. The right eye was operated in allunder Local anesthesia (xylocaine2%.). A longitudinal slit was made in the cornea of normal eye extending the middle of pupullary space. The lens was extracted intact.The cytolysed iris tissuealong with bit Part of retina was injected into the denucleated eyes of operated froglet. For making the cytolysed implants eye ball were taken out from the donar froglets and lens were removed from these eye balls and the anterior half of these eye balls were taken and homagenized in saline,later which were used for transplantation. One or Two drops of cytolysed extract was injected in the host denucleated right eye only. Precautions were taken to inject the cytolysed tissue Just beneath the Cornea. in each operated all operation were done under stereoscopic binocularmicroscope. The vitamin A preparation used was Vitamin A palmitate (aqua Sol 50000 IU).The working solution of vitamin A was of 15 IU/ml strength.Solution was injected intraperitoneally on alternate day after lentectomy. The Experiment were carried out at room temperature (30°C)) For the preparation of working solution. The solution was prepared by dissolving a known quantity of this drug in a small amount of ethanol to make a stock. solution and then diluting a certain quantity from the stock solution with appropiate amount of water. The animals were preserved one day 3 and day 25 after operation for histological study. The preservation of the animals at similar intervals was also done in control group for comparitive study after keeping the animals in bouin solution for 24-30 hrsand were transferred in 70% alcohol. For histological study the eyes were removed from the preserved animals and dehydrated in alcohol series then cleaned in Xylene and were embedded in parrafin wax. The Eyes were sectioned and stained withhaematoxyleneand counter stained witheosin. The Experiment were made on 2 groups. The experiment were performed on 60 Animals and most of them were kept alive for 25 daysfollowing operation but some of each group were sacrificed, fixed and their eyessectioned. The day of operation was designated as 0. Plan of Experiment was as follow- Group A - The froglets with transplanted eyetissue but no treatment was given Group B - The froglets with transplanted eye tissue and does received vitamin A treatment. |
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| Result and Discussion |
The cytolysed implants transplanted into the enucleated eye balls differentiated in this new location autonomously to give rise to lens regenerates showing various degrees of development in different cases. The results of development of transplanted implants in control and treated groups are described below. Control - Out of 30 implants made 2 were not taken and were sloughed off the three implants differentiated into unidentified structures. Histologically, they consisted of accumulated groups of unidentified cells. The group was looking simply pycnotized tissues (Fig-1). The remaining implants did not show any differentiational changes. Treated- In 30 froglets cytolysed extracts of iris and bit part of retinal tissues had been transplanted of these one graft was not taken and was thrown out, the remaining implants showing various degree of development in different cases. In 18 cases double lenses observed. Most of them were located in the anterior chamber near the dorsal and ventral iris on day 25 after operation. One of these two lenses was smaller in size. It seems that lens developed from the implanted tissues was comparatively smaller in size then that developed from Host's iris. Otherwise the stages of differentiation of the double lenses were identical (Fig - 2,3). Irrespective of their size attained by the end of experiment both of them possessed primary and secondary lens fibers similar to that of intact lens. Each lens was surrounded by normal cuboidal lens epithelium. Lens fiber pole directed medially towards the host neural retina. Many secondary lens fiber differentiations appeared in the equatorial zone. In 7 out of 18 cases iris like structure developed from the transplanted implants (Fig-4). It seems that transplanted implants transformed not only into second lens but also in to the iris part. This is quite interesting to note that the regenerated iris part always associated with the lens. As shown in table-1, there were some cases where abnormal lens development occurred. Three categories are listed: fused lens with vacuolated fibers, (Fig-5) herniated fibers or degenerating fibers. No clear correlation between these abnormalities and the type of operation or site of development of the implant could be determined. Vacuolated fibers were observed in a total of 11 cases. In these lenses, a few or many of the lens fibers had broken-down leaving clear spaces among remaining lens fibers which ranged from small to very large. These vacuoles involved primary lens fiber, secondary lens fibers or both. Listed under herniated fibers were those lenses where a mass of irregular bare fibers protruded from the lens fiber pole. Complete disintegration of lens fibers into acidophilic debris was also observed in two cases. One less severe abnormality was associated with the site where the lens vesicle was developing. Among the implants lying within the vitreous chamber when the pupil was occupied by thehost lens, an attenuation of the lens epithelium was quite often observed. This ranged from a continuous lens epithelium of very flat squamous cells. through an apparently discontinuous layer of these cells to a lens completely lacking a lens epithelium. They do not have a clear equatorial zone of lens fiber differentiation since lens fibers seemed to have formed from epithelial cells over the entire surface of the lens. Regarding the size of the regenerated lenses are no clear conclusion could be drawn.) In some cases the lens developed from the host iris was larger and other cases the lens transformed from the implants was larger.
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| Conclusion |
From the precent studies several conclusion of fundamental nature emerges which make it possible to advance certain plausible hypothesis. It has demonstrated that vitamin A induced and accele rated the lens formation from dorsal iris andimplant of cytolysed iris in froglets of Rana cynoph lyctis. The froglets of group a (control group) did not show lens regeneration, however, in vitamin A the treated group of froglets. (Group B) 96.7% froglets Showed lens for regenerati and double lenses were observed in 18 out of 30froglets. In remaining fused lens with vacuolated fibres, herniated fibres and in few lens with degenerating fibres were reported. Vitamin A might have removed the inhibition factor by some how, the exact mechanism is Still not well known. However Maden (1988) suggested that retinoid Enters to cell eighter via unidentified Surface receptor or by lipophilic inter Calation through the membrane and then bind to cytoplasmic binding protein and a complex is formed. Chytil and ong 1984, Patkovidh etal 1987 also reported to such binding proteins in most of the cells, one specific for retinoic acid, Cellular retinoic acid binding protein (CRABP) and one specific for retinol cellular retinoic acid binding protein. The complex then enter to the nucleus where it alter the pattern of gene CRPP transcription. Thus it can be suggested
that retinoic add play an important role in the trans mission of their ligands
from the cell memb. to the nucleus Where the patterns of gene activity may be
altered. |
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| References |
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