104
ALFRED J. COULOMBRE
any stage in development, the cornea is at about the same stage of
maturation from its center to its margins would indicate that this
peripheral growth zone must be an extremely narrow one located at the
sharp line of junction between the corneal tissues and the adjacent
stroma with which it is continuous. Detailed information is needed concerning the mechanisms which underlie the increase in area of the cornea at
all stages during its maturation.
I X . Corneal Morphogenesis in Relationship to Eye Morphogenesis
The size, shape, position and orientation of the tissues of the vertebrate eye are so well regulated in the course of embryonic development
that the adult organ is an excellent optical instrument. It is becoming
increasingly apparent that the precise geometric relationships of the
parts of the eye are brought about by complex interactions among them.
The induction of the cornea by the lens and eye cup assures that from
the outset it will be properly positioned and aligned with them. Their
continued operation during a significant portion of development
probably keeps this alignment constantly adjusted.
A complex of interactions among the layers of the cornea determine
and maintain its structure, and are responsible for such diverse properties as its transparency, its deturgescence, its biréfringent patterns,
its avascularity, and its ability to regenerate. Systemic influences range
from the relatively non-specific fulfillment of nutritional requirements to
the role of thyroxin in precipitating corneal dehydration. Lopashov
(1963) has drawn together a wealth of material on the developing
vertebrate eye that illustrates that no simple step-by-step chain of
reactions can account for anything as complex as ocular morphogenesis.
Each tissue is under a barrage of internal and external influences at each
stage in its development. With the cornea, as with the eye as a whole,
the task is to identify these influences, to characterize them, and to
learn when and how and upon what target they act during development.
We have reached a point when it is both possible and profitable to map
these complex interactions not only to reflect current kijowledge but to
bring clearly into focus those gaps in our knowledge whose exploration
will inevitably force us to alter and perfect our maps.
Acknowledgements
I acknowledge gratefully the assistance of Mrs. Jane Coulombre and
Mrs. Sonia Rothschild with the library search; of Mrs. Ruth Jordan
with the secretarial work; and of Mrs. Mary Ann Welsh, Mr. Ed.
Etheredge and Mr. Edwin Moodhe with the illustrations.
ALFRED J. COULOMBRE
any stage in development, the cornea is at about the same stage of
maturation from its center to its margins would indicate that this
peripheral growth zone must be an extremely narrow one located at the
sharp line of junction between the corneal tissues and the adjacent
stroma with which it is continuous. Detailed information is needed concerning the mechanisms which underlie the increase in area of the cornea at
all stages during its maturation.
I X . Corneal Morphogenesis in Relationship to Eye Morphogenesis
The size, shape, position and orientation of the tissues of the vertebrate eye are so well regulated in the course of embryonic development
that the adult organ is an excellent optical instrument. It is becoming
increasingly apparent that the precise geometric relationships of the
parts of the eye are brought about by complex interactions among them.
The induction of the cornea by the lens and eye cup assures that from
the outset it will be properly positioned and aligned with them. Their
continued operation during a significant portion of development
probably keeps this alignment constantly adjusted.
A complex of interactions among the layers of the cornea determine
and maintain its structure, and are responsible for such diverse properties as its transparency, its deturgescence, its biréfringent patterns,
its avascularity, and its ability to regenerate. Systemic influences range
from the relatively non-specific fulfillment of nutritional requirements to
the role of thyroxin in precipitating corneal dehydration. Lopashov
(1963) has drawn together a wealth of material on the developing
vertebrate eye that illustrates that no simple step-by-step chain of
reactions can account for anything as complex as ocular morphogenesis.
Each tissue is under a barrage of internal and external influences at each
stage in its development. With the cornea, as with the eye as a whole,
the task is to identify these influences, to characterize them, and to
learn when and how and upon what target they act during development.
We have reached a point when it is both possible and profitable to map
these complex interactions not only to reflect current kijowledge but to
bring clearly into focus those gaps in our knowledge whose exploration
will inevitably force us to alter and perfect our maps.
Acknowledgements
I acknowledge gratefully the assistance of Mrs. Jane Coulombre and
Mrs. Sonia Rothschild with the library search; of Mrs. Ruth Jordan
with the secretarial work; and of Mrs. Mary Ann Welsh, Mr. Ed.
Etheredge and Mr. Edwin Moodhe with the illustrations.