The Cornea in Normal Condition and in Groenouw's Macular Dystrophy

The three most striking characteristics of the cornea are: a) Its structure or rather its perfectly regular architectonic, by virtue of which it is transparent. b) The absence of vessels, the cornea being nourished by the perilimbic vessels, the endothelial surface in communication with the aqueous humour and the epithelial surface in contact with the pre-corneal film. c) The very slow turnover of the cells, that is to say the keratocytes, with the result that the metabolism of the cornea is very weak. It is this third characteristic which justifies our present investigation. The keratocytes, which are apparently inactive, have in fact a latent activity. They can be activated by central corneal incisions and also by tissue cultures. Under either of those conditions, the keratocytes become very active, develop all the cytoplasmic organites and produce mucopoly­ saccharides as well as the precursors of the collagen (Fig. 1). In order to study the pathological keratocyte, we chose a storage disease, wherein the catabolism of the mucopolysaccharides is blocked, namely the macular dystrophy of the cornea. We undertook the same investigation both for normal and for pathologi­ cal corneas and studied the keratocyte 'in situ' and in tissue cultures using various microscopical and histochemical techniques. In macular dystrophy, we investigated also the deteriorations secondary to the changes in the keratocytes.

one: Normal keratocytes.- I: Material and methods.- I. Material.- II. Methods.- A. Histological and histochemical techniques.- B. Culture techniques for normal keratocytes.- C. Technique for the study of the corneal architectonic.- D. Histochemical techniques.- III. Discussion.- A. Mucopolysaccharides.- B. Collagen and reticulin.- C. Lysosomes.- D. Mitochondria.- IV. Microscopy.- V. Photography.- II: Normal keratocytes in situ.- I. Introduction.- II. Personal results.- Discussion and conclusions.- III: Architectonic of the cornea.- I. Introduction.- II. Personal results.- A. Flat sections.- B. Transversal sections.- C. Study of flat sections at the polarisation microscope.- D. Study of the transversal sections at the polarisation microscope.- E. Study of the mucopolysaccharides.- F. Topo-optical study.- G. Diffraction by X-rays.- H. Examination of collagen-mucopolysaccharide complexes at the high-resolution electron micoscope.- I. Macromolecular model of the corneal stroma.- Discussion.- IV: The keratocytes in the process of cicatrisation of the corneal stroma.- I. Personal observations.- A. Transformation of the keratocytes in a wound.- B. Histochemical evolution of the keratocytes in the course of cicatrisation.- Discussion and conclusions.- V: Keratocytes in tissue culture.- I. Introduction.- II. Personal observations.- A. Examination of the primary cultures in vivo during growth.- B. Examination of the sub-cultures in vivo during growth.- C. Examination at the phase-contrast microscope of living monolayers, mounted in Ringer’s solution.- III. Histochemical study.- IV. Electron microscopy.- V. Scanning microscopy.- Discussion and conclusions.- two: Pathological keratocytes (Macular dystrophy of the cornea).- VI.- I. Definition of macular dystrophy of the cornea.- II. Clinical characteristics.- III. Heredity.- Conclusions.- VII: Microscopical and histochemical study of macular dystrophy.- Personal observations.- A. Phase-contrast microscopy of fresh sections and of sections fixed before and after dehydration.- B. Optical microscopy of histochemically stained sections.- C. Polarisation microscopy and topo-optical staining.- D. Dark-field microscopy.- Discussions and conclusions.- VIII: Transmission electron microscopy of the corneal stroma in macular dystrophy of the cornea.- Personal observations.- A. Superficial layers of the corneal stroma.- B. Keratocytes.- I. First stage of the keratocyte degeneration.- II. Second stage of the keratocyte degeneration.- III. Third stage of the keratocyte degeneration.- IV. Fourth and final stage of the keratocyte degeneration.- C. Intercellular corneal stroma.- Discussions and conclusions.- IX: Scanning electron microscopy of the corneal stroma in macular dystrophy.- Personal observations.- Conclusion.- X: Changes of the epithelium, the base membrane, the endothelium and the Descemet’s membrane in macular dystrophy of the cornea.- Personal observations.- I. Deterioration of the epithelium and the base membrane.- A. Optical microscopy and histochemistry.- a. Examination at the clear-field microscope of stained sections.- b. Phase-contrast microscopy of fresh or histochemically stained sections.- c. Polarisation microscopy of histochemically stained sections.- d. Dark-field microscopy of stained sections.- B. Electron microscopy.- C. Scanning electron microscopy.- II. Changes of the endothelium and the Descemet’s membrane.- Discussion.- Conclusion.- XI: Histochemical and microscopical study of corneal cultures from macular dystrophy.- Personal observations.- I. Development of the cultures.- II. Examination of the implantation specimen.- III. Microscopy.- A. Implanted fragment.- B. Keratocytes in monolayer.- Discussion.- Conclusions.- XII: Transmission electron microscopy of cultures of the corneal stroma in macular dystrophy.- Personal observations.- Discussion.- Conclusions.- XIII: Scanning electron microscopy of cultures of macular dystrophy of the cornea.- Personal observations.- Comparative study of normal keratocytes and keratocytes affected by macular dystrophy.- Conclusions.- XIV: Vital staining of the lysosomes in normal keratocytes and in keratocytes from macular dystrophy.- Personal observations.- I. Normal keratocytes.- Cell division.- Dynamics of the vital staining.- II. Keratocytes in macular dystrophy.- Dynamics of the vital staining in keratocytes from macular dystrophy.- Conclusions.- XV: Active biological substance present in normal keratocytes and capable of acting on the stored mucopolysaccharides in macular dystrophy of the cornea.- Personal observations.- I. Experiment.- II. Results.- Discussion and conclusions.- XVI: Pathogenesis of macular dystrophy of the cornea.- XVII: Treatment of macular dystrophy of the cornea.- Summary.- Summary.