Animal Body Function VIII PDF

Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 5th February 2024  www.egasmoniz.com/pt...

Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 5th February 2024  www.egasmoniz.com/pt Summary This presentation is for educational purposes only - Photoreceptor system - Anatomy of the eyeball - Histology of the eyeball - Anatomy of the accessory organs - Histology of the accessory organs Master’s Degree in Veterinary Medicine - References - König, HE, Liebich, HG. (2014).Veterinary Anatomy of Domestic Mammals:Textbook and Color Atlas (6th ed.). Stuttgart: Schattauer. - Evans, HE, Miller, ME (2013).Miller's Anatomy of the Dog(4th ed.). St. Louis, Missouri: Elsevier. Dyce, KM (2010).Textbook of veterinary anatomy (4)thed.). St. Louis, Missouri: Elsevier. Thomson, C., Hahn, C. (2012). - Mescher, A. (2021). Junqueira’s Basic Histology: Text and Atlas (16th ed.). New York: McGraw-Hill Education - Hans-Georg Liebich. Veterinary histology of domestic mammals and birds (5th Edition). 5m Publishing. 2019. ISBN 9781789180091 - Eurell, J.A., Frappier, B.L. (2006). Dellmann’s Textbook of Veterinary Histology (6th ed.). Blackwell Publishing. ISBN 9780781741484 - Bacha, W.J., Bacha, L.M. (2012). Color atlas of Veterinary Histology (3rd ed.). Wiley-Blackwell. ISBN 9780470958513 Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt - The eye is a photosensitive organ, which enables the conversion of a light stimulus (photons) into an This presentation is for educational purposes only electrical stimulus (nerve impulse) which will then be processed at the CNS level. - Is located in the orbit Master’s Degree in Veterinary Medicine - Konig, 2020 Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt Eyeball: This presentation is for educational purposes only - Fibrous layer/tunic - Vascular layer/tunic - Internal or nervous layer/tunic - Lens Master’s Degree in Veterinary Medicine Accessory organs - Extrinsic muscles of the eyeball - Eyelids - Lacrimal apparatus - Orbit (orbital fat body) - Orbital fasciae Optic nerve Konig, 2020 ABF VII Visual area Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Dyce, 2018 Eyeball: This presentation is for educational purposes only - Position in the head is related to the animal’s environment, habits and method of feeding; - - Predatory species (cat and dog) Master’s Degree in Veterinary Medicine - Eyes set forward – binocular vision (focus on near objects; perception of depth) - Prey species (horses, ruminants, rabbits) - Eyes more laterally – right and left fields of vision hardly overlap (large field of vision; little capacity for binocular vision) Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt This presentation is for educational purposes only Spherical shape (horses and cattle – some anteroposterior compression) - Anterior pole (1) - - Posterior pole (2) - Optic axis (3) Master’s Degree in Veterinary Medicine - Equator (4) - Meridian (5) - Optic nerve (6) - Limbus (7) Dyce, 2018 Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt Eyeball: This presentation is for educational purposes only - Fibrous layer/tunic - Vascular layer/tunic - Internal or nervous layer/tunic - Lens Master’s Degree in Veterinary Medicine Accessory organs - Extrinsic muscles of the eyeball - Eyelids - Lacrimal apparatus - Orbit (orbital fat body) - Orbital fasciae Optic nerve Konig, 2020 ABF VII Visual area Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( ) This presentation is for educational purposes only Cornea Sclera Master’s Degree in Veterinary Medicine - Dyce, 2018 Konig, 2020 - Composed by very dense collagenous tissue – gives the eye shape and stiffness - Limbus or Corneoscleral junction: where the sclera and cornea meets Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Located in the anterior pole of the eyeball Transparent and avascular layer Dyce, 2018 Composed by five layers: - https://histologyguide.com/slideview/MHS-229- 1. Anterior epithelium (epithelium anterius) Master’s Degree in Veterinary Medicine 2. Subepithelial basement membrane 3. Stroma (substantia propria cornae) 4. Posterior limiting lamina (Descemet’s membrane, eye/20-slide-1.html?page=2 lamina limitans posterior) 5. Posterior epithelium (epitelium posterior) Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Located in the anterior pole of the eyeball Transparent and avascular layer Composed by five layers: - 1. Anterior epithelium (epithelium anterius) Master’s Degree in Veterinary Medicine - Corneal epithelium: nonkeratinized stratified squamous epithelium - Presence of microvilli on the surface of the superficial cells – retain the tear film on the corneal surface - Numerous free nerve endings are present among the epithelial cells 2. Subepithelial basement membrane Consists of a basal lamina and a layer of reticular fibers Liebich, 2019 In humans, primates and birds: Bowman’s membrane – modified layer of the substantia propria Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Located in the anterior pole of the eyeball Transparent and avascular layer Composed by five layers: - 3. Stroma (substantia propria cornae) Master’s Degree in Veterinary Medicine - Collagen fibers (type I is the most common) - Constitutes 90% of the corneal thickness - Principal cell: fibrocyte (located between collagen fibers) Corneal transparency dependent on the: - Optimal hydration of the stroma; - Maintenance of the regular arrangement of collagen fibrils. Liebich, 2019 These factors minimize the scattering of the incident light. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Located in the anterior pole of the eyeball Transparent and avascular layer Composed by five layers: - 4. Posterior limiting lamina (Descemet’s membrane, Master’s Degree in Veterinary Medicine lamina limitans posterior) - Corresponds to a thick basement membrane of the posterior epithelium - Present collagen type VIII 5. Posterior epithelium (epitelium posterior) - Also called corneal endothelium - Simple squamous epithelium Liebich, 2019 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Innervation of the cornea (sensory) Trigeminal n. (nerve V) → Ophtalmic n. (nerve V1) → Nasociliary n. → Long ciliary nerves - (This is assessed in the neurologic Master’s Degree in Veterinary Medicine examination with the corneal reflex) Animal Body Function VIII 2023/2024  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only ( Opaque layer ) ( Composed by dense connective tissue cornea: dense collagenous tissue )- – https://histologyguide.com/slideview/MHS-229- eye/20-slide-1.html?page=2 Dyce, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Dyce, 2018 Opaque layer https://histologyguide.com/slideview/MHS-229- - Composed by dense connective tissue Master’s Degree in Veterinary Medicine - Episcleral layer - Proper substance of the sclera - Lamina fusca of the sclera eye/20-slide-1.html?page=2 - Area cribosa - Scleral ring Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Opaque layer - Composed by dense connective tissue Master’s Degree in Veterinary Medicine - Episcleral layer: loose collagen fibers - Proper substance of the sclera (substantia propria): dense network of collagen fibers in parallel orientation - Lamina fusca of the sclera: layer adjacent to the choroid. Present elastic fibers, fibrocytes and melanocytes https://histologyguide.com/slideview/MHS-229-eye/20-slide- 1.html?page=2 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Opaque layer - Composed by dense connective tissue Master’s Degree in Veterinary Medicine - Area cribosa: present many fenestrations, through which the blood vessels and the axons that will give rise to the optic nerve pass Bacha, 2012 Legend: 3- Choroid; 9- Lamina cribosa; 13- Nerve fibers; 14- Optic disk; 15- Optic nerve; 19- Retina; 21- Sclera Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Rostrally, the sclera is covered by the conjunctiva. - Scleral ring (Annulus sclerae): In the limbus or corneoscleral Master’s Degree in Veterinary Medicine junction – the sclera thickens and is covered by fibroelastic tissue. Internal structure → corresponds to the place where the insertion of the ciliary muscles occurs (ciliary body) - Plexus venosus sclerae: adjacent to the annulus sclerae. Drains the aqueous humour and participate in regulation of intraocular pressure. Evans, 2013 Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt Eyeball: This presentation is for educational purposes only - Fibrous layer/tunic - Vascular layer/tunic - Internal or nervous layer/tunic - Lens Master’s Degree in Veterinary Medicine Accessory organs - Extrinsic muscles of the eyeball - Eyelids - Lacrimal apparatus - Orbit (orbital fat body) - Orbital fasciae Optic nerve Konig, 2020 ABF VII Visual area Animal Body Function VIII 2023/2024  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only Iris Choroid Ciliary body ( ) – Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only The choroid is a thick, highly vascularized layer: - Rostrally: is continuous with the stroma of the ciliary body - Extends posteriorly around the globe - https://virtualanimalanatomy.colostate.edu/ - External surface: connected with the sclera Master’s Degree in Veterinary Medicine - Internal surface: attached to the pigmented epithelium of the retina Layer rich in blood vessels, spread in loose connective tissue Blood vessels: important role in retinal nutrition Presence of choroidal melanocytes: give dark colour to the posterior cavity Guarantees that the light that enters and will be processed by the retina is exclusively the one that passes through the pupil Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Histologically, the choroid is divided into five layers. 1. Suprachoroid layer 2. Vascular layer - 3. Tapetum lucidum https://virtualanimalanatomy.colostate.edu/ 4. Choriocapillary layer Master’s Degree in Veterinary Medicine 5. Basal complex Retina Eurell, 2006 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Histologically, the choroid is divided into five layers. 1. Suprachoroid layer: stablish loose connection between the choroid and Bacha, 2012 the sclera. - - Connective tissue with numerous pigmented cells. 2. Vascular layer: thickest layer of the choroid. Master’s Degree in Veterinary Medicine - Composed by pigmented connective tissue and large vessels. - Large vessels – extend into the choriocapillary layer. Eurell, 2006 3. Tapetum lucidum 4. Choriocapillary layer: dense network of capillaries adjacent to the pigmented epithelium of the retina. Capillaries provide nutrients to the retina. 5. Basal complex (Bruch’s membrane): serves as a barrier between the blood in the choriocapillary vessels and the retinal pigmented epithelium. Animal Body Function VIII 2023/2024  – https://virtualanimalanatomy.colost www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Histologically, the choroid is divided into five layers. 3. Tapetum lucidum ate.edu/ - Present in the domestic mammals (except the pig and camelids); - - Absent in birds - Located dorsal to the optic disc Master’s Degree in Veterinary Medicine - Choroidal reflective layer; In the region where the tapetum lucidum is present, the retinal pigment epithelium is non-pigmented and translucent. Increases visual capacity in low light areas → reflets the light from the tapetum lucidum which results in additional retinal stimulation Tapetum lucidum cellulosum: carnivores Tapetum lucidum fibrosum: herbivores Cat Konig, 2020 Animal Body Function VIII 2023/2024  Bacha, 2012 – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Histologically, the choroid is divided into five layers. 3. Tapetum lucidum Tapetum lucidum cellulosum (22): carnivores - - Composed by a variable number of flat polygonal cells. Master’s Degree in Veterinary Medicine Tapetum lucidum fibrosum (22): herbivores - Formed by collagen fibres and few fibrocytes The refraction of light is caused by the spatial orientation of cells (carnivores) or collagen fibers (herbivores)  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only Eurell, 2006 – Choroid Animal Body Function VIII 2023/2024 Bacha, 2012  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only Iris Choroid Ciliary body ( ) – Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only The ciliary body is the thickened middle segment of the vascular tunic, between the choroid and the iris. - - Starts at the Ora serrata and ends with the beginning of the iris. - Participates in the formation of the framework of the iridocorneal Master’s Degree in Veterinary Medicine angle - Composed by: - Ciliary processes - Ciliary zonulae - Ciliary muscle Organized as: - Aqueous humor - Ciliary ring - Crown of ciliary body (corona ciliaris, Evans, 2013 pars plicata) Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Composed by: - - Ciliary processes: - Ciliary zonulae Master’s Degree in Veterinary Medicine - Ciliary muscle - Aqueous humor Liebich, 2019 Liebich, 2019 Organized as: Ciliary ring (orbiculus ciliaris, pars plana) Posterior portion of the ciliary body – relatively flat. Cover by fibers of the ciliary zonule (or zonule fibers). Crown of ciliary body (corona ciliaris, pars plicata): Evans, 2013 Anterior portion that contains the ciliary processes. Dyce, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Composed by: Ciliary processes: ridges that extend from the vascular region of the ciliary body. - Provide a large surface area - Serve as the origin for zonular fibers (that attach to - the lens) - Covered by a double layer of low columnar epithelial Master’s Degree in Veterinary Medicine cells, the ciliary epithelium. Evans, 2013 Liebich, 2019 Dyce, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Composed by: Ciliary processes Ciliary epithelium - -- Outer pigmented epithelial layer: Next to the basal lamina (correspond to the basal complex of the choroid), that continues with Master’s Degree in Veterinary Medicine the stroma of the vascular layer Cells contain melanin and correspond to the anterior projection of the pigmented retina epithelium - Inner nonpigmented epithelial layer: Basal lamina separates the cells from the posterior chamber. Lacks melanin. Contiguous with the sensory layer of the retina and with the pigmented epithelium of the iris. The cells of this double epithelium present extensive basolateral folds Eurell, 2006 with Na+/K+-ATPase activity → production of the aqueous humor. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Composed by: Ciliary processes Ciliary zonulae or zonular fibers (ZF) - Produced by the nonpigmented epithelial cells of the - ciliary epithelium → from the corona ciliaris (through the ciliary processes) and from the ciliary ring (flat part). Master’s Degree in Veterinary Medicine - They suspend the lens. Evans, 2013 Mesher, 2018 Liebich, 2019 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Composed by: Ciliary processes (CP) Ciliary zonulae (CZ) Ciliary muscle (CM) - - Composed by smooth muscle fibers oriented in a circular, meridional and radial position, intermingled with elastic fibers. Master’s Degree in Veterinary Medicine - Contraction of the muscles affects the shape of the lens – important for visual accommodation Mesher, 2018 Liebich, 2019 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only Histologically: - Ciliary epithelium - Vascular layer: - - Suprachoroid layer, vascular layer and basal complex → maintains the layers of the choroid Master’s Degree in Veterinary Medicine - Ciliary muscle - Direct anterior continuation of the choroid Evans, 2013 Animal Body Function VIII 2023/2024  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only Iris Choroid Ciliary body ( ) – Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Constitutes a flat ring that is attached at its periphery to the sclera - Located anterior to the lens - Separates the anterior and posterior chambers → - communication between the two chambers is made by a central opening, the pupil. Master’s Degree in Veterinary Medicine Function: prevent the entry of light, except those that will form the image (and will impress the retina). Evans, 2013 Liebich, 2019 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Organized as: - Margo pupillaris - Free margin of the iris Iridial granules (Granula iridica or corpora nigra) - ruminants and horses - - Margo ciliaris - Periphery of the iris. Continuous with the ciliary body and the iridocorneal angle Master’s Degree in Veterinary Medicine - Dilator muscle of the pupil (m. dilator pupillae) - Sphincter muscle of the pupil (m. sphincter pupillae) - Pectinate ligament – ligament that attaches the iris to the sclera, in the iridocorneal angle. Part of the aqueous drainage system. - Composed by: - Iridial stroma - Iridial muscles (Sphincter and dilator muscles) - Iridial epithelium or Posterior epithelium Eurell, 2006 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Organized as: - Margo pupillaris or Pupillary margin - Free margin of the iris Iridial granules (Granula iridica or corpora nigra) - ruminants and horses - - Present in the anterior and posterior pupillary margin. - Formed by proliferations of the pigmented epithelium and increased Master’s Degree in Veterinary Medicine vascularization of the iris stroma. Secrete aqueous humor. Konig, 2020 Bacha, 2012 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Composed by: - Iridial stroma - Iridial muscles (Sphincter and dilator muscles) - Iridial epithelium or Posterior epithelium Master’s Degree in Veterinary Medicine - Eurell, 2006 Mescher, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Composed by: - Iridial stroma (S) Loose connective tissue that present melanocytes (pigmented layer) and fibrocytes. Highly vascularized - Epithelium is lacking or is discontinuous in the anterior surface of the iris Master’s Degree in Veterinary Medicine Eye color depend on the amount of pigmentation within the pigment containing cells of the stroma. Mescher, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Composed by: - Iridial stroma (S) - Iridial muscles - Sphincter (SPM) and dilator muscles (DPM) Regulate the size and the shape of the pupil - Mammals – smooth muscle cells Birds – striated skeletal muscle cells → allows to faster adjustments to Master’s Degree in Veterinary Medicine changes in light (comparing with the mammals) Mescher, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) - This presentation is for educational purposes only - Composed by: - Iridial stroma (S) - Iridial muscles - Sphincter (SPM) and dilator muscles (DPM) - Iridial epithelium or Posterior epithelium - Continuation of the inner nonpigmented epithelial layer of the ciliary processes. In ungulates – presence of iridial granules. Master’s Degree in Veterinary Medicine Pigmented epithelial layer Mescher, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) This presentation is for educational purposes only – Autonomic nervous system - - Sympathetic nervous system – innervates the dilator pupillae muscle, Master’s Degree in Veterinary Medicine the blood vessels of the iris; the ciliary processes; - Parasympathetic nervous system – innervates the sphincter dilator pupillae and the ciliary muscle Short ciliary nerves is formed: - Post ganglionic fibers of the Ciliary ganglion → Oculomotor nerve (parasympathetic nerve) - Post ganglionic fibers of the cranial cervical ganglion → Sympathetic ganglion https://vmerc.uga.edu/CranialNerves/plra.html  www.egasmoniz.com/pt Eyeball: This presentation is for educational purposes only - Fibrous layer/tunic - Vascular layer/tunic - Internal or nervous layer/tunic - Lens Master’s Degree in Veterinary Medicine Accessory organs - Extrinsic muscles of the eyeball - Eyelids - Lacrimal apparatus - Orbit (orbital fat body) - Orbital fasciae Optic nerve Koning, 2020 ABF VII Visual area Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt This presentation is for educational purposes only Origin: ectoderm Transparent biconvex structure suspended immediately behind the iris Insensitive and avascular tissue → receives nutrition from the aqueous - humor - Highly elastic – a property that decreases with the age Master’s Degree in Veterinary Medicine - Separates the posterior chamber from the vitreous body - Composed: - Lens capsule - Lens epithelium - Lens fibers The lens is suspended by the ciliary zonules - Lens + ciliary zonules + ciliary muscle → allows the process of visual accommodation Allows focusing on near and far objects by changing the curvature of the Evans, 2013 lens. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt This presentation is for educational purposes only - Composed: Lens capsule: - Refractive capsule form by the secretions of the lens epithelium; eye/20-slide-1.html?x=11948&y=19209&z=27.1 - https://histologyguide.com/slideview/MHS-229- - Composed by a basal lamina – type IV collagen and glycoproteins Master’s Degree in Veterinary Medicine - Place for insertion of the Zonular fibers Lens epithelium: - In the anterior surface of the lens; - Simple cuboidal epithelium - Only cells that are capable of replication. In some places can differentiate in lens fibers Lens fibers Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt This presentation is for educational purposes only - Composed: Lens capsule: - Refractive capsule form by the secretions of the lens epithelium; eye/20-slide-1.html?x=11948&y=19209&z=27.1 - https://histologyguide.com/slideview/MHS-229- - Composed by a basal lamina – type IV collagen and glycoproteins Master’s Degree in Veterinary Medicine - Place for insertion of the Zonular fibers Lens epithelium: - In the anterior surface of the lens; - Simple cuboidal epithelium - Only cells that are capable of replication. In some places can differentiated in lens fibers Lens fibers Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt This presentation is for educational purposes only - Composed: Lens capsule: Lens epithelium: eye/20-slide-1.html?x=11948&y=19209&z=27.1 - https://histologyguide.com/slideview/MHS-229- Lens fibers - Elongate prismatic cells – form the most part of the lens; Master’s Degree in Veterinary Medicine - The lens fibers end up losing the nucleus and contains water, membrane proteins, enzymes, crystallins and electrolytes. - The shape of the lens is determined by the cytoskeleton (fibronectin, vimentin and actin) Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt Eyeball: This presentation is for educational purposes only - Fibrous layer/tunic - Vascular layer/tunic - Internal or nervous layer/tunic - Lens Master’s Degree in Veterinary Medicine Accessory organs - Extrinsic muscles of the eyeball - Eyelids - Lacrimal apparatus - Orbit (orbital fat body) - Orbital fasciae Optic nerve Koning, 2020 ABF VII Visual area Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Blind part of the retina, Non sensory portion - Pars caeca retinae - Optical part of the retina, Sensory portion – Pars optica retinae Master’s Degree in Veterinary Medicine - Both portions present an inner and an outer layer Ora serrata: boundary between the two portions of the retina; it also demarcates the choroid from the ciliary body Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Blind part of the retina, Non sensory portion - Pars caeca retinae - Region without photoreceptors. - Covers the iris and the ciliary body: - - Pars iridica retinae - Pars ciliaris retinae Master’s Degree in Veterinary Medicine Double layer of a cuboidal epithelium Corresponds to: Iridial epithelium or Posterior epithelium (Iris) Ciliary epithelium (Ciliary body) - The blind part exists because these region cannot be impressed by Evans, 2013 light rays. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Optical part of the retina, Sensory portion – Pars optica retinae https://virtualanimalanatomy.colostate.edu/ - Provided with light sensitive receptor cells – photoreceptors - - Responsible for the transduction of light energy into chemical energy → electrical impulses that are conducted by the optic nerve to the Master’s Degree in Veterinary Medicine visual centers of the brain. - Thicker when compared with the blind part - Composed: - Outer retinal pigmented layer (stratum pigmentosum) - Inner neural layer (stratum nervosum) - Optic disk Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Optical part of the retina, Sensory portion – Pars optica retinae - Composed: - Outer retinal pigmented layer (stratum pigmentosum) - Formed by simple cubic epithelium with pigment; Master’s Degree in Veterinary Medicine - Closely attached to the choroid → between the basal complex (choroid) and the outer segment of the photoreceptors - Flat or polygonal layer of cells resting on the basal lamina - Numerous melanin granules are present, except in the cells overlying the tapetum. https://histologyguide.com/slideview/MHS-229-eye/20- slide-1.html?x=11948&y=19209&z=27.1 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Optical part of the retina, Sensory portion – Pars optica retinae - Composed: - Outer retinal pigmented layer (stratum pigmentosum) - Functions: Master’s Degree in Veterinary Medicine - Transport of nutrients and metabolites from the capillaries of the choriocapillary layer to the inner neural layer; - Absorption of light by the melanin – supplement the choroid; - Forms part of the blood retina barrier (due to the tight junctions between the cells) - Retinal regeneration - Phagocytosis. Eurell, 2006  – www.egasmoniz.com/pt ( ) ( )- This presentation is for educational purposes only Optical part of the retina, Sensory portion – Pars optica retinae - Composed: - Outer retinal pigmented layer (stratum pigmentosum) Inner neural layer (stratum nervosum) – photosensitive layer Master’s Degree in Veterinary Medicine - Formed by neurons and glial cells - Optic disk Eurell, 2006