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ORIGINAL ARTICLE
Year : 1983  |  Volume : 31  |  Issue : 2  |  Page : 69-72

Relationship of glucose-6-phosphate dehydrogenase with structural development and growth of human fetal cornea


Department of Biochemistry, Institute of Post Graduate Medical Education and Research Calcutta, India

Correspondence Address:
Abhijit Sen
Professor & Head Department of Biochemistry I. P. G. M.E. R.. 244, Acharya J.C. Bose Road, Calcutta 700 020
India
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Source of Support: None, Conflict of Interest: None


PMID: 6662571

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How to cite this article:
Sen A, Mukherjee K L. Relationship of glucose-6-phosphate dehydrogenase with structural development and growth of human fetal cornea. Indian J Ophthalmol 1983;31:69-72

How to cite this URL:
Sen A, Mukherjee K L. Relationship of glucose-6-phosphate dehydrogenase with structural development and growth of human fetal cornea. Indian J Ophthalmol [serial online] 1983 [cited 2020 Oct 31];31:69-72. Available from: https://www.ijo.in/text.asp?1983/31/2/69/27440



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Cornea is both ecto and mesodermal in origin. The enzyme glucose-6-phosphate dehy­drogenase belongs to the hexose monophos­phate shunt which is essential for the synthe­sis of ribose, deoxyribose and reduced NADP. required for lipid synthesis. The G-6-PD activity is absent in stromal keratocyte.[1] The hexose monophosphate shunt activity is pri­marily located at the epithelial layer of cornea. About 70°/p of glucose oxidation in the corneal epithelium accounts for hexose monophos­phate shunt.[3] The D-ribose-5-phosphate generated by the pathway is used in the nucleic acid synthesis and the reduced NADP is used for the synthesis of the lipid content of cell membrane of the corneal epithelium. To the best of authors knowledge, the present work is the first ever attempt to analyse and co-relate the histological development with glucose-6-phosphate dehydrogenase level of human fetal cornea.


  Materials and mfthods Top


The human fetuses were obtained from the M. T. P. Clinic of the Department of Obstetrics and Gynaecology. They were taken out of the uterus in their entirety by hystero­tomy in multiparous mothers who did not want to continue their pregnancy and also opted for ligation at the same time. Informal consents were obtained from the mothers for the use of their fetuses and the project was cleared by the ethical subcommittee of the Institute. Normal fetuses obtained from mothers in good health were selected for the present study.

The eyes were immediately enucleated, the entire cornea of one eye was dissected out, weighed to the nearest tenth of a milli­gram and used for the biochemical estimation. The other eye was used for the study of his­tological development of cornea. The G-6-PD activity of cornea was estimated by the method of Warburg et a1[4], the histology of cornea was staining with eosin and haem­atoxylin.


  Observations Top


Histological development of human fetal cornea was followed from 7 to 24 weeks of gestation by haematoxyline-eosin staining. The surface ectoderm which remains near the optic cup, forms the corneal epithelium. The lens vesicle which appears in the inner side of surface ectoderm [Figure - 1], gets detached from it [Figure - 2] and forms the lens. Mesodermal invasion starts below the developing cornea.

The differentiation of these cells transform it into a fully formed cornea [Figure - 3][Figure - 4].

[Table - 1] shows the anthropometry of the fetuses and their G-6-PD content. The G-6­PD content was found to increase gradually from 0.45 µm/minute/gm. protein of cornea at 9 weeks to 2.5 µm,/minute/gm. protein of cornea at 16 weeks of gestation which stayedat this level up to 24 weeks of gestation. Estimation of G-6-PD level of fetuses above 24 weeks of gestation could not be undertaken on account of lack of availability of suitable fetuses at that age group. Likewise study with gestational period of less than 7 weeks were left out due to technical difficulty in the dissection of cornea at this period. The specific activities of G-6-PD of fetal ophthalmic tissue is lower than that of fetal liver. The G-6-PD level of adult cornea is almost double the level of fetal cornea and more than that of adult liver. The relationship of fetal body weight with the G-6-PD activities of fetal cornea is shown graphically in [Figure - 5].


  Discussion Top


Histological development of the cornea is characterized by an organised growth of sur­face epithelium, below which the mesodermal cells invaginate and become transformed into various layers of the cornea, The number of cells per unit area varies at different period of gestation. Presumably growth rate also varies paripassu. For growth, the syntheses of ribose and deoxyribose are necessary and the operation of G-6-PD shunt pathway would be needed.

The G-6-PD activity of cornea increase from a low level in earlier period to a high level around mid-gestation. This rapidly incre­asing level of G-6-PD is probably due to the greater demand made on it to meet the most active phase of growth of cornea at this period. In the later period of gestation the corneal growth rate is more or less steady as it has already attained its histological matu­rity, this keeps the G-6-PD level more or less the same. High G-6-PD level of adult cornea is probably due to its multi-layered epithelium which is the site of hexose monophosphate shunt for cornea,

Contrary to the observation of Masterson et al which was however on chick cornea, the human fetal corneas were observed to remain transparent during the period of gestation and no relationship could be established between the transparency of cornea and G-6-PD level in human fetuses.


  Summary Top


The histological development of healthy human fetal cornea belonging to 9 to 24 weeks of gestation were studied in relation to G-6­PD level. G-6-PD activities of human fetal cornea gradually increased from 9 to 16 weeks and then staved at that level up to 24 weeks of gestation. G-6-PD activities of human fetal cornea was lower than that of adult cornea. Human fetal corneas have been observed to remain transparent during the period of ges­tation.


  Acknowledgement Top


Grateful acknowledgements are due to Prof. S. K.Bhattacharjee, Head of the Depart­ment of Obstetrics and Gynaecology Mr. Santanu Sen of 1. E. G. Consultants (Pvt. Ltd) for kind help in this study. The study was supported by the l. C. M. R., New Delhi.[5]

 
  References Top

1.
Baum. J. L., 1963, Arch. Ophthalmol Chicago. 70 : 59.  Back to cited text no. 1
    
2.
Kinoshita. J. H..1962, Invest. Ophthalmol 1:178.  Back to cited text no. 2
    
3.
Kuhlman, R, E. and Resnik. R. A., 1959. Arch. Biochem. Biophys. 85 : 29.  Back to cited text no. 3
    
4.
Warburg, O., Christian. W, and Griese. A., 1935, Biochem. 2 : 282.  Back to cited text no. 4
    
5.
Masterson. E., Edelhouse, H. F. and Chander, G. J., 1978, Biochim. Biophys. Acta. 542 : 372.  Back to cited text no. 5
    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]
 
 
    Tables

  [Table - 1]



 

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Materials and mf...
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