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Abstract
The size, shape, position, and orientation of the tissues of the vertebrate eye relative to each other fall within the narrow geometric tolerances compatible with the optical function of this organ. During embryonic development the establishment and maintenance of appropriate relationships among the several ocular tissues remit from an orderly complex of specific interactions among the tissues. Each tissue may be studied as a source of influence on other tissues or, alternatively, as a target of influences arising from other tissues. This paper focuses attention on the lens. The lens may be considered as a target of influences which emanate from the eyecup and neural retina and which are involved in lens induction, lens fiber differentiation, lens suture orientation, lens growth, and the orientation of the lens relative to the optic axis. The lens, in its turn, is a source of influence in the induction of corneal anterior epithelium from ectoderm and in the control of the accumulation of the vitreous substance. The accumulation of vitreous substances importantly influences the size and shape of the pigmented epithelium, choroid coat, and sclera. The analysis of each tissue as both a source and a target of influences permits the construction of flow sheets of tissue interactions in the developing eye. These floio sheets provide a rational basis for understanding the teratology of this organ and represent causal chains which must connect at many points with events at the molecular and chromosomal levels.