✅ EMBRIOLOGÍA del OJO 👁🎨
Introduction and Development of the Eye
In this section, the speaker discusses the embryological development of the eye, focusing on key structures such as the optic cup and lens vesicle.
Embryological Development of the Eye
- The eye begins to form with shallow grooves on both sides of the prosencephalon in a 22-day-old embryo.
- These grooves develop into evaginations called optic vesicles, which later contact the overlying ectoderm to initiate lens formation.
- Optic vesicles then invaginate to form a double-walled optic cup. Initially separated by an intraretinal space, the two layers eventually fuse.
- The development includes the choroidal fissure allowing arteries and nerves to reach the eye's inner chamber.
- Cells from the surface ectoderm give rise to the lens placode, which forms into the lens vesicle by week five.
Differentiation of Retinal Layers
This part delves into the differentiation of retinal layers during eye development, highlighting features like pigmentary layers and photoreceptor cells.
Retinal Layer Differentiation
- The outer layer of the optic cup becomes known as the pigmented layer due to its pigment granules.
- The neural layer within differentiates into various cell types including rods and cones for light reception.
- Surrounding these layers are fibrous layers containing neuronal axons that converge at the optic disc.
- Light impulses traverse multiple retinal layers before reaching rods and cones for visual processing.
- A portion known as "blind spot" retains its thickness initially but later divides into iris-related and ciliary parts.
Formation of Iris and Ciliary Body
This segment explores how structures like iris, ciliary body, and suspensory ligaments form during eye development.
Iris and Ciliary Body Formation
- The iris comprises an unpigmented outer layer from the optic cup and an active tissue layer housing pupil muscles.
- The ciliary region exhibits pronounced folds externally giving rise to ciliary muscles internally connected via suspensory ligaments to support lens positioning.
Development of Lens Fibers
Here, details about how lens fibers elongate within developing lenses are discussed.
Lens Fiber Development
- Posterior wall cells elongate anteriorly forming primary fibers that fill up space within developing lenses by week seven.
Desarrollo del Nervio Óptico
This section discusses the development of the optic nerve, focusing on the connection between the optic cup and the brain through the optic stalk, as well as the formation of key structures like the choroidal fissure.
Development of Optic Nerve
- The optic cup connects to the brain via the optic stalk, which features a ventral groove known as the choroidal fissure. This area houses blood vessels and fibers.
- By the seventh week of development, the choroidal fissure closes, creating a narrow tunnel within the stalk. The increasing number of nerve fibers leads to fusion of its inner and outer walls.
- As more nerve fibers develop, cells in the inner layer contribute neuroglial support, transforming the optic stalk into the optic nerve. Blood supply includes an arterial branch that becomes central retinal artery.