  In order to better understand the mechanisms underlying the physiology of
vision, it is a necessary prerequisite to know the embryological bases of eye
development and associated tissues. Eye formation starts during the fourth week
of human embryonic life, when the ocular primordium can be distinguished from
the lateral diverticula of the anterior brain by complex morphogenetic
movements. It requires the input of various germ layers of the embryo:
neuroectoderm, surface ectoderm, mesoderm and neural crest cells, in order to
elaborate the different components. Perturbations of the cellular interactions
and molecular mechanisms mobilized during these critical steps are responsible
for varied congenital anomalies. We will discuss, relative to this, the
embryological processes where their misregulation are at the root of ocular
malformations and which are developed in more detail in other chapters of this
book.
