Hello everyone! Welcome to my channel Today we are going to give Eye Embryology A short, simple topic and I tried to do it as practical as possible Let's start with the Optical Cup and Lens Vesicle In the 22 day embryo the eye appears as a pair of grooves shallow on both sides of the forebrain When the Neural Tube is closed the grooves form evaginations in the forebrain called optic vesicles Later they come into contact with the Superficial Ectoderm producing in it, the changes necessary for the formation of the lens Shortly after, the optic vesicles begin
to invaginate to constitute the Optical Cup double-walled Initially, the inner and outer layers of this cup are separated by a light called Intraretilian Space but soon the light disappears and the 2 layers come together Invagination is not limited to the central portion of the glass but includes a part of the bottom surface that forms the Choroidal Fissure This allows the hyaloid artery to reach to the inner chamber of the eye During the 7th week the lips of the Choroidal Fissure merge and the mouth of the optical cup becomes in a round opening known as the
Future Pupil During the previous processes the cells of the Superficial Ectoderm (initially in contact with the optic vesicle) begin to elongate to create the Placoda del Cristalino Then this one, invagina becomes in the lens vesicle In the 5th week the lens vesicle loses contact with the surface ectoderm to then be placed in the mouth or internal portion of the Optical Cup RETINA, IRIS AND CILIARY BODY It is called the Retina Pigment Layer to the Outer Layer of the Optical Cup characterized by small pigment granules The development of the Inner Layer or also known as Neural
of the Dome or Optical Cup it is more complex The 4/5 parts that constitute the Optical Part of the Retina contain cells around of the intraretinal space they differ in Rods and Cones The canes are more numerous and sensitive than the cones but without detecting color like cones. Along with this Photoreceptor Layer is the Cloak of the Mantle that generates Neurons and Support or Support Cells between them: the External Nuclear Layer, the Inner Nuclear Layer and the Layer of Ganglion Cells On the surface, there is a Fibrous Layer containing axons of neurons of the deepest
layers In this area nerve fibers converge on the Optical Stem which will become in the Optic Nerve Therefore, the light impulses they cross most of the layers of the Retina before reaching the Rods and Cones The 5/5 anterior part of the Inner Layer also known as the Blind Part of the Retina preserves the thickness of a layer Later it is divided into the Iridescent Part or Portion of the Retina that constitutes the Inner Layer of the Iris and the Ciliary Part or Portion of the Retina, that participates in the formation of the Ciliary Body Meanwhile,
the region between the Dome or Optical Cup and the Superficial Epithelium that covers it it is full of loose mesenchyme The Sphincter and Dilator Muscles of the Pupil are formed in this tissue In the adult the Iris is constituted by the Outer layer without pigment of the Optical Cup and for a layer of connective tissue very vascularized containing the pupil muscles The Ciliary Part of the Retina easily identified by its pronounced folds Outside, it is covered by a layer of mesenchyme that gives rise to the Ciliary Muscle Inside, it connects to the Crystalline through a
network of elastic fibers Known as Suspensory Ligament or Zonula Regarding CRYSTALLINE Shortly after the lens vesicle formed posterior wall cells begin to lengthen earlier to produce long fibers little by little they fill the light of the Vesicle Towards the end of the 7th week those Primary Crystalline Fibers reach the Anterior Wall of the Lens Vesicle However, the growth of crystalline does not end in this phase Why other secondary fibers constantly added to the central core CHOROID, SCLEROTIC AND CORNEA At the end of the fifth week The Primordium of the Eye it is completely surrounded by
a loose mesenchyme This fabric soon differs In an Inner Layer and in an Outer Layer Inner Layer produces a pigmented layer highly vascularized known as choroid The Outer Layer becomes the Sclera and it continues with the Duramadre around of the Optic Nerve It differs in another way Mesenchymal Layers that line the front of the eye The anterior chamber is formed by vacuolation and divide the mesenchyme in an Inner Layer in front of the Crystalline and Iris called the Iridopupillary Membrane and an Outer Layer that is continued with the Sclera known as Cornea's Own Substance The
Rear Chamber is the space between the Iris in front and the Ciliary Body behind The Anterior and Posterior Chambers communicate through the Pupil and they are full of a liquid called aqueous humor product of the Apophysis or Ciliary Process of the Ciliary Body Transparent Watery Humor circulates from the posterior chamber even inside the previous chamber supplying the nutrients to the cornea and the lens that lack vascularization BODY OR VITREOUS HUMOR The mesenchyme not only surrounds the ocular primordium from the outside In addition, it invades the interior of the Optical Cup through the Choroidal Fissure Here,
create the Hialoid Cups that during intrauterine life irrigate the Lens to constitute the Vascular Layer on the inner surface of the Retina In addition, it produces a network of fibers between the lens and the retina Later, the interstitial spaces of the network are filled with a transparent gelatinous substance thus creating the Vitreous Body The Hialoid Vessels of this region are obliterated and disappear during fetal life leaving behind the Hyaloid Duct And regarding the development of OPTIC NERVE The Optical Cup connects to the brain through the Optical Stem on whose ventral surface there is a groove
known as Choroidal Fissure In this groove, the Hialoid Glasses On his return to the Brain the Nervous Fibers of the Retina are between the cells of the Internal Wall of the Optical Stem During the 7th week of development Choroidal Fissure closes and a narrow tunnel appears inside the Optical Stem Due to the increasing number of Nerve Fibers the inner wall of the stem grows merging its inner and outer walls The cells of the Inner Layer provide a Neuroglia network where the fibers are held of the Optic Nerve And so, the Optical Stem is transformed into
the Optic Nerve The center of it will contain a portion of the Hyaloid Artery which will later be called Retina Central Artery And outside, you will be surrounded by an extension of the Choroid and Sclera known as Piamadre, Arachnoid and Duramadre Well, that's all we have reached the end of the video I hope it has been useful to you Thank you so much for watching and if you liked it and want to see more videos Subscribe
