The main structures involved in the development of the eye and adnexa are neuroectoderm of the prosencephalon, ectoderm of the cephalic lining, neural crest cells (ectomesenchyme), and mesoderm. Eye development begins with the formation of shallow optic grooves on each side of developing forebrain. As the neural tube closes, the optic grooves expand to form optic vesicles which remain attached to the brain by optic pedicles. Thickenings of the surface ectoderm over the optic vesicles give rise to the lens. As soon as the optic vesicle induces the formation of the lens placodium and then the lens vesicle, this invades the distal part (the dome) of the optic vesicle and forms the optical cup. This has two walls, one internal, the outline of the sensory retina, and another external, the pigmented epithelium of the retina. The optic stalk becomes the optic nerve. At the pupillary border, the neuroepithelium of the optic cups remains thin and will be the blind part of retina. The invaginated inner wall corresponds to the mantle layer (ML), which at the eye fundus is continued by differentiating optic nerves fibers. Photoreceptor cells, bipolar cells, horizontal cells, amacrine cells, ganglion cells, and interplexiform cells, Müller’s cells, astrocytes, and oligodendrocytes in the optic nerves are derived from the ML and microglia from the mesoderm of yolk stalk. The structural changes in retinal cells, the complex organization of their different layers from the embryonic period to birth, and the involvement of genes, transcription factors, growth factors, and other tissue factors are analyzed. The embryology and remodeling of the vitreous, as well as the different cell types involved in these processes, are also commented on in this chapter.