PROBLEMS IN CORNEAL MORPHOGENESIS
ALFRED J. COULOMBRE
Laboratory of Neuroanatomical Sciences,
National Institute of Neurological Diseases and Blindness,
National Institutes of Health,
U.S. Public Health Service,
Department of Health, Education and Welfare,
Bethesda, Maryland, U.S.A.
I. Introduction
81
II. Induction of the Cornea
83
III. Anterior Epithelium
85
IV. Stromal Architecture and Properties
87
A. Postepithelial Layer....87
B. Stromal Fibroblasts
89
C. The Fiber Matrix
95
V. The Posterior Epithelium
99
VI. Descemet's Membrane
99
VII. Transparency of the Cornea
100
VIII. Growth and Shaping of the Cornea
103
IX. Corneal Morphogenesis in Relationship to Eye Morphogenesis
104
References
:
105
I. Introduction
During the development of the cornea of the vertebrate eye three
basic cell types (exclusive of nerve fibers) and a relatively modest list of
extracellular substances are brought together in space and time in such
a manner that a large number of quite different functions are served.
Ectodermal cells form the stratified squamous anterior epithelium at
the surface of the cornea. Mesothelial cells form the simple cuboidal
posterior epithelium. Stromal corpuscles (fibroblasts) of mesodermal
origin are scattered in the stroma, a collagenous layer which is sandwiched between the two epithelia and whose anterior portion is, in
some species, differentiated into a cell-free area called Bowman's
membrane. The acellular Descemet's membrane separates the posterior
face of the stroma from the posterior epithelium. A detailed description
of the adult cornea is given by Duke-Elder (1961) and by Maurice
(1962).
The functional problems which must be solved in the development of
the cornea are reflected in this fist of its properties : sensitivity to pain,
81