DEVELOPMENT OF NERVOUS SYSTEM AND SENSORIC ORGANS 1 Functions of nervous system 2 oControl of other body tissues and organs oPerception of stimuli from the environment and reactions oPerception of stimuli from body and reactions oAbility to learn and memory creation oPerception of body and limb positition Nervous system anatomy and physiology: Video | Osmosis https://www.osmosis.org/learn/Nervous_system_anatomy_and_physiology Embryonic origin of nervous system 3 oPrimitive streak formation in epiblast layer of bilaminar disc oEpiblast layer cells migrate through primitive streak to space between epiblast and hypoblast, replacement of hypoblast cells oFormation of trilaminar disc: oEndoderm – inner layer oMesoderm – middle layer oEctoderm – outer layer oNervous system forms from ectoderm, originally epiblast Teach Me Anatomy Neurulation 4 oEctoderm influenced by factors produced by notochord oadjacent ectoderm differentiate into neuroectoderm oformation of thickened neuroectoderm layer – neural plate olateraly in neural plate – neural ridges, neural groove between them → neural ridges move towards each other, fusion along midline – formation of neural tube (basis for central nervous system) ointerface between ectoderm and neuroectoderm – region of neural tube fusion – formation of neural crest cells population (basis for peripheral nervous system) Teach Me Anatomy Neural groove Convergence of neural ridges Nervous system 5 oStructures formed during neurulation: oNeural tube – basis for development of central nervous system oNeural crest – basis for development of peripheral nervous system oNeural tube: obrain oSpinal cord oNeural crest: oPeripheral neurons oEnteric neurons oGlial cells Development of neural tube 6 obrain forms from cranial neural tube, spinal cord from caudal oclosing neural tube from cranial region (4. somite) to caudal – cranial and caudal parts stay temporarily open, formation of cranial and caudal neuropores (communication of neural tube with amnion) ofirst closure of cranial neuropore, later caudal neuropore oEnclosed neural tube divided along dorsoventral axis: oVentral – floor plate, development influenced by notochord oventrolateral – basal lamina/plate – motor neurons odorsolateral – alar lamina/plate – sensory neurons odorsal – roof plate, development influenced by surface ectoderm (epidermis) oSulcus limitans – divide basal and alar lamina O`Kane and Begg. Clinical Embryology Spinal cord brain Cranial neuropore Caudal neuropore Developmental defects of neural tube closure 7 oAnencephaly oCranial neuropore closure defect oReduced formation of brain, or its part (telencephalon) oOften lethal oSpina bifida oDefect of caudal neuropore closure oCleft, prolapse of spinal cord osurgery Initial differentiation of neural tube cells 8 oNeural tube lined by pseudostratified cylindrical epithelium oNeuroepithelium differentiate into two major types of progenitors: oneuronal progenitors (neuroblasts) – formation of central nervous system cells oglial progenitors (glioblasts) – formation of CNS supporting cells oNeural tube neuroepithelium differentiate into 3 basic layers: oInner (germinal/ventricular) layer – neural tube cavity lining epithelium oMantle layer – spinal cord grey matter oMarginal layer - periphery Germinal (ependymal) layer Formation of neural tube layers 9 Inner germinal layer Mantle layer Marginal layer neuroblast Neuronal protrusion Glial cell (astrocyte, oligodendroglia) oCells formed from glioblasts: oastrocytes – formed in mantle and marginal layer ooligodendroglia – especially in marginal layer Glial cell (astrocyte) Neural tube wall histogenesis 10 oDifferentiation of neural tube cells – from germinal neuroepithelium oNeuroblast lineage – development of neurons oApolar neuroblast – progenitor without protrusions oBipolar neuroblast – formation of two protrusions oUnipolar neuroblast – one protrusion oNeuron – formation of one axon, development of dendrites oGlioblast lineage – development of supporting cells oSpongioblast – glial cells progenitor oAstroblast – astrocytic progenitor (blood-brain barrier) oOligodendroblast – progenitor of oligodendroglia (CNS neurons myelination) oependyma – epithelial cells forming neural tube lining → important for development of choroid plexus omesenchyme – microglia development (nervous system monocytic cells) Radial glia 11 o ospecialized neural cells (bipolar morphology – similiarly to neuroepithelial cells oLong protrusions from ventricular zone (germinal epithelium) to marginal layer osupporting cells for migration of immature neurons from germinal epithelium to marginal layers of developing epithelium oprogenitor cell for development of: oneurons oGlial cells oimportant for differentiation of cells in specific CNS regions Brain development – primary brain vesicles 12 oBrain development in cranial region – region of neural plate extension oFormation of 2 flexures of neural tube: oCervical – flexure between hindbrain and spinal cord oCephalic – ventral flexure in the midbrain region oFrom neural plate extension, 3 primary brain vesicles formed: oprosencephalon – forebrain omesencephalon – midbrain orhombencephalon – hindbrain oBrain compactness and small space for its development → Cervical flexure Cephalic flexure Brain development – secondary brain vesicles 13 o3 primary vesicles transform to 5 secondary brain vesicles oRhombencephalon oMetencephalon – cranial part; pons Varoli, Cerebellum oMyelencephalon – caudal part; Medulla oblongata oProsencephalon: oTelencephalon – cranial part; brain hemispheres, olfactory lobe oDiencephalon – caudal part; eye cups, thalamus, neurohypophysis, epiphysis oMesencephalon – no division hemispheres Rhombencephalon 14 oafter neuropore closure – expansion of lateral rhombencephalic walls dorsally oroof plates extend laterally and dorsally – formation of diamond-shaped structure – fourth ventricle oBrain ventricle covered by thin ependymal cell layer ocranialy – formation of metencephalon ocaudally – formation of myelencephalon dorsal ventral Sadler, 1990. Langman`s medical embryology Myelencephalon 15 omyelencephalon – caudal rhombencephalon omyelencephalon – connection of spinal cord and brain → Medulla oblongata oExtension of walls laterally – alar plates localized laterally, basal plates medially oFormation of dorsal (roof) and ventral (floor) plates oroof plate compose of one layer of ependymal cells covered by cells of developing vessels (mesoderm) – pia mater (vascular cover closely attached to brain) Sadler, 1990. Langman`s medical embryology oependyma and pia mater of 4. ventricle → tela choroidea, invagination to 4. ventricle – formation of choroid plexus (production of cerebrospinal fluid) odevelopment of cranial nerves - VI. abducens, VII. facial, VIII. vestibulocochlear, IX. glossopharyngeal, X. vagus, XI. accessory, XII. hypoglossal dorsal ventral 9., 10., 11. 12. Metencephalon 16 ometencephalon – cranial rhombencephalon ometencefalon – development of dorsally localized Cerebellum and ventrally localized pons Varoli odevelops similarly to myelencephalon – extension of walls laterally – alar plates laterally, basal plates medially dorsal ventral Sadler, 1990. Langman`s medical embryology oDevelopment of V. cranial nerve - trigeminal odorsolaterally – formation of rhombic lips (basis for Cerebellum) 5., 7. 6. Cerebellum development 17 ooriginates in dorsolateral parts of alar plate of rhombencephalon – rhombic lips oRhombic lips come together in mesencephalon region – proliferation of rhombic lip cells – formation of precursors of cerebellar hemispheres oFurther proliferation results in connection and fusion medially – one cerebellum formed covering 4. ventricle Edited: McGeady et al. Veterinary Embryology. 2009 mesencephalon metencephalon myelencephalon Alar plate Basal plate Rhombic lip diencefalon Mesencephalon 18 oslight developmental changes compared to other parts omedial expansion of alar and basal plates – reduction of neural canal – formation of mesencephalic aquaduct oBasal plate – formation of motoric nuclei of cranial nerves (III. oculomotor, IV. trochlear) ocrura cerebri – expansion of peripheral parts of basal plate – roots for descending nerves from cereberal cortex to pons and spinal cord Sadler, 1990. Langman`s medical embryology oneuroblasts from alar plates settle tectum (dorsal part of mesencephalon) – formation of 4 nuclei (colliculi) with visual and auditory function osubstancia nigra – migration of alar cells ventrally (dopamine production), motoric function rostral and caudal colliculi Prosencephalon 19 orostral part of brain – telencephalon rostrally, diencephalon caudally oCavity of diencephalon – 3. brain ventricle oCavity of telencephalon – paired lateral ventricles Diencephalon 20 oCaudal part of forebrain oDoes not form basal plates – formation from alar and roof plates oFormation of 3 medial protrusions from lateral walls: odorsally – epithalamus (1) omiddle – dorsal thalamus (2), subthalamus (3) oventrally – hypothalamus (4) oGrowth of thalamus (sensoric center of brain) medially to ventricle – reduction of cavity ohypothalamus – center for sleep, digestions, termoregulation, behaviour oventrally – formation of neurohypophyseal infundibulum oCaudal part of epithalamus – epiphysis cerebri – endocrine gland (melatonin) https://www.brainkart.com/article/Subdivision-of-Diencephalon-s-Structure_14831/ Hypothalamo-hypophysal system 21 HYPOTHALAMUS oVentral part of diencephalon (tuberal hypothalamus with the pituitary stalk, mammilary bodies) + caudal part of telencephalon (preoptical area) oSymmetrically duplicated parts divided by the 3rd ventricle o HYPOPHYSIS Diencephalon – infundibulum - Neurohypophysis (pars nervosa) Oral cavity endoderm – Rathke´s pouch - Adenohypophysis (pars distalis) o o o https://www.researchgate.net/publication/273833506/figure/fig13/AS:267977153052688@1440902140374/No rmal-development-of-the-pituitary-gland_W640.jpg https://www.researchgate.net/publication/273833506_Magnetic_resonance_imaging_of_sellar_and_juxtase llar_abnormalities_in_the_paediatric_population_an_imaging_review/figures?lo=1 Telencephalon 22 oThe most rostral brain region – central part lamina terminalis, 2 lateral diverticles – formation of hemispheres oCavities of lateral diverticles communicate with 3. ventricle of diencephalon oexpansion of hemispheres – reduction of lateral ventricles and 3. ventricle oDevelopment of telencephalon – first rostral expansion, further dorsal expansion, subsequent caudal expansion, finally ventral expansion – formation of C-shaped hemispheres oHemispheres cover diencephalon, mesencephalon and rostral rhombencephalon – formation of brain cortex Edited: McGeady et al. Veterinary Embryology. 2009 oBiggest region – development of centers for learning and memory, intellect and emotions telencephalon telencephalon telencephalon Differentiation of cells in brain cortex 23 o3 basic zones – ventricular, intermediate, marginal oOnset of cortex formation – asymmetric division of radial glial cells – formation of radial glia and neurons oIntermediate progenitors (IP) migrate from ventricular to subventricular zone – symetric division of IPs – formation of identical neurons omigration of IPs to cortical zone through intermediate zone (future white matter) oCortical layer formed of (from inner to outer regions): oFusiform – smaller pyramidal cells, interneurons oInner pyramidal layer – bigger pyramidal neurons oInner granular – dense small granular cells oOuter pyramidal – pyramidal cells, short protrusions oOuter granular – dense small granular cells omolecular – stelate and basket cells Scott Gilbert. Developmental Biology 10th edition Developmental defects of brain 24 oMacrocephaly oExpansion of individual brain regions oMajor cause – enhanced proliferation of neurons and glial cells oHydrocephaly oHigher production and accumulation of cerebrospinal fluid in brain, often caused by altered connection between ventricles oEnlarged ventricles cause higher pressure in brain olead to headache, problems with balance, double vision, mental changes mouse brain atlas section10 mouse E12 Nasal cavity Lateral Ventricle Septum Olfactory bulb Cerebral cortex Hypothalamus Thalamus Midbrain Aquaduct of sylvii Cerebellum Fourth Ventricle Choroid plex Myelenceph. Pons Rathke pouch mouse E12 Development of spinal cord 27 odevelopment of spinal cord from neural tube caudally from rhombencephalon O`Kane and Begg. Clinical Embryology Spinal cord brain oalar and basal plates – formed by proliferation of neuroblasts in mantle layer oalar – formation of sensory and interneurons obasal – formation of motoric neurons ointensive proliferation, fusion of plates – typical butterfly shape of grey matter Obsah obrázku text, perokresba Popis byl vytvořen automaticky oEnclosed neural tube divided along dorsoventral axis: oVentral – floor plate, development influenced by notochord oventrolateral – basal plate – motor neurons odorsolateral – alar plate – sensory neurons and interneurons odorsal – roof plate, development influenced by surface ectoderm (epidermis) oSulcus limitans – divide basal and lateral plates Development of ventral and dorsal spinal cords 28 oFormation of motor neurons (basal plate): oVentral cord – motor axon outgrows from neuroblast – inervation of effector organ (muscle) oLateral cord – motoric axon outgrows from neuroblast to autonomic ganglion, axons outgrows from axons of autonomic ganglion – inervation of autonomic organ (gut) oFormation of sensory neurons (neural crest): osomatic neuroblast of dorsal ganglion – one protrusion outgrows towards dorsal spinal cord, other protrusion terminates in somatic sensory receptor (skin) Edited: McGeady et al. Veterinary Embryology. 2009 oviscelar neuroblast of dorsal ganglion - one protrusion outgrows towards dorsal spinal cord, other protrusion terminates in visceral sensory receptor (gut) Development of spinal nerves 29 ointerneurons – connection between CNS neurons oReceive information from sensory neurons or interneurons oTransmission of information to motor neurons or interneurons oefferent fibers – lead signals from CNS to tissues and organs, formed from basal plates oafferent fibers – lead signals from periphery to CNS, formed from neural crest cells otogether – spinal nerve, formed of dorsal (afferent) and ventral (efferent) fibers Edited: McGeady et al. Veterinary Embryology. 2009 Development of peripheral nervous system 30 oNervous system outside the brain and spinal cord: oCranial and spinal nerves oSensory and autonomic ganglia oSupporting cells oNeural crest: oAfferent nerve fibers oPostganglionic neurons oSpinal, head and autonomic ganglia oGlial cells oPlacodal tissues (ectodermal placodes of sensory system): opart of cranial neurons and ganglia oCNS – efferent somatic and autonomic fibers from basal plates Development of dorsal root ganglia (DRG) 31 oBodies of neurons responsible for transmission of sensory information from receptors (termoreceptors, nociceptors, proprioreceptors, chemoreceptors) to CNS oBodies of neurons separated by satellite glial cells – preventing transmission of signals between bodies oTrunk neural crest cells migrate ventrally omigration terminated medially from somites oformation of two cell populations: oSensory neurons oGlial cells (Satellite glia, Schwann cells) oneuron: oDorsomedial outgrowth (neural tube) oVentrolateral outgrowth (connected to developing spinal nerve) Autonomic nervous system 32 oGeneral visceral efferent system – involuntary regulation of systems (smooth and cardiac muscles, exocrine and endocrine glands) oDivided to: osympathetic oparasympathetic oin contrast with somatic efferent system (one neuron), autonomic system formed of two neurons oconnection takes place in autonomic ganglion (neural crest) Delloye-Bourgeois and Castellani, 2019. Front Mol Neurosci Sympathetic nervous system 33 oSympathetic fibers: opreganglionic - short opostganglionic - long oGanglia formed close to neural tube Delloye-Bourgeois and Castellani, 2019. Front Mol Neurosci oMyelination: oMyeline sheet formed from Schwann cells oPostganlionic axon not myelinated oSympathetic system develops: opreganglionic neurons – trunk and lumbar spinal cord opostganglionic neurons and ganglion - sympatoadrenal population of trunk neural crest Parasympathetic nervous system 34 oParasympathetic system develops: oPreganglionic axons – brain stem (part of cranial nerves – Oculomotor, Facial, Glossopharyngeal, Vagus) oGanglia and postganglionic neurons – from cranial, vagal and lumbosacral neural crest oParasympathetic fibers: oPreganglionic – long oPostganglionic – short oParasympathetic ganglia formed close to or directly in innervated tissue oMyelination: oFormation of myeline sheet from Schwann cells oPost-ganglionic axon not myelinated Enteric nervous system 35 oFormed from 2 sources: oVagal neural crest (hind brain), inervation of almost the whole gut – including first 2/3 of colon oLumbosacral neural crest, inervation of last 1/3 of colon and rectum Larsen Human Embryology, 2008 oNeural crest cells migrate to wall of developing gut, formation of nerve plexus: osubmucosa – Meissner`s plexus oExternal muscle layer – Auerbach`s plexus oControl of gut motility, secretion, transport of water and electrolytes, vascularization of mucosa Development of CNS meninges 36 oOrigin of meninges – different for brain and spinal cord oCranial brain – neural crest (forebrain) oCaudal brain and spinal cord – paraxial mesoderm oCNS meninges: oOuter layer – dura mater oMiddle layer – arachnoidea oInner layer – pia mater oneural tissue protection, attachement to bones (cranium, backbone), flow of cerebrospinal fluid Dasgubta and Jeong, 2019. Genesis oDevelopment from mesenchymal sheath - primary meninx oDifferentiation of primary meninx: oPachymeninx – dura mater oLeptomeninges – arachnoidea and pia mater Early Development of the Brain https://www.notesonzoology.com/zoology/development-of-brain-in-chick/2697 Three-Part Division of the Brain For years it was assumed that the avian brain was limited in function because it lacked a neocortex. he mammalian cortex is organized into six layers containing vertical columns of neurons that communicate with one another both horizontally and vertically. The avian brain, on the other hand, was thought to be arranged into discrete collections of neurons called nuclei, including a region called the dorsal ventricular ridge, or DVR, and a single nucleus named the wulst. Avian brain •Early development resembles the mammal brain • •Main difference – lack of neocortex • •In mammals - information flow among the brain's layers • •In birds - interconnected nuclei with bands of neurons • •Both microcircuits of info are analogic • •Increased optic region Study finds mammalian and avian brains share corticosensory microcircuit https://medicalxpress.com/news/2015-02-mammalian-avian-brains-corticosensory-microcircuit.html DEVELOPMENT OF SENSORY ORGANS 39 Functions of sensory organs 40 oDevelopment of structures specific for perception of stimuli oTastes and smells perception oSounds perception oOptical perception oWater flow perception and electric field perception oStructures for perceving body position and balancing Sensory Organs Brain Images: Browse 6,746 Stock Photos & Vectors Free Download with Trial | Shutterstock EYE ◦ 41 Anatomy Of Human Eye And Descriptions Stock Illustration - Download Image Now - Anatomy, Human Eye, Diagram - iStock Embryonic origins of individual eye parts 42 oNeural epithelium of diencephalon – retina, iris including smooth muscles, optic nerve, part of vitreous body o oSurface ectoderm – lens, cornea, conjunctiva, eyelids, lacrimal duct oPrechordal mesoderm (preotic mesoderm) – external occulomotor muscles oNeural crest (prosencephalon a mesencephalon) – part of epithelium and stroma of cornea, stroma of iris, stroma and muscles of ciliary body, sclera Williams and Bohnsack, 2015. Birth Defects Res C Embryo Today Randolph and Pavlath, 2015 Veterian Key Development of optic groove and optic vesicle 43 oformation of optic grooves on both sides of forebrain (neural ridges) oEnclosure of neural tube – formation of sacs from grooves – optic vesicles oOptic vesicles grow from forebrain through mesenchyme towards the surface ectoderm oDuring growth – connection between forebrain and optic vesicle is prolonged – optic stalk (basis for optic nerve) ointeraction between optic vesicle and surface ectoderm – induction of epithelial thickening (lens placode) in ectoderm (lens precursor) Veterian Key Optic groove Neural ridge Neural groove Optic grooves Neural groove Optic vesicle ectoderm Optic vesicle forebrain ectoderm Lens placode Lens placode Optic stalk Development of eye basis 44 oinduction of invagination epithelium of lens placode – formation of lens depression ofrom lens placode is formed circular structure – further invagination – separation of structure from surface ectoderm – formation of lens vesicle oconcurrently invagination of optic vesicle epithelium – formation of doublelayered epithelial structure – optic cup oepithelial double layer of optic cup – basis for development of retina Veterian Key Invaginating lens placode forebrain Optic vesicle Lens placode Surface ectoderm Optic cup mesenchyme stalk Lens vesicle Surface ectoderm Developing lens Surface ectoderm Epithelial double layer of cup Development of retina 45 obasis – epithelial double layer (outer thinner, inner thicker) of optic cup osmaller anterior (A) part – iris and ciliary body olarger posterior (B) part - retina lens Intra-retinal space vessels Optic nerve Developing eyelid ectoderm Undifferentiated mesenchyme Pigmented retina layer Neural layer of retina A B oPosterior part: oInner epithelial layer – neural layer of retina (photosensory) oOuter epithelial layer – pigmented retina layer oseparated by intraretinal space Veterian Key Neural retina histogenesis 46 olayer adjacent to intraretinal space – photoreceptors (rods and cones) oOuter nuclear layer – bodies of receptor cells oOuter plexiform layer – formation of synapses between photoreceptors and bipolar neurons, horizontal cells (signal integration) oInner nuclear layer – bipolar, horizontal and amacrine cell bodies (signal transmission to ganglion cells) oInner plexiform layer – synapses between bipolar, amacrine and ganglion cells oGanglion cell layer – ganglion cell bodies oNerve fiber layer – ganglion cell axons oMüllerian cell (M) – glial cell, supporting retinal cell Origin of extraocular muscles 47 oExtraocular muscles develop from 2 sources: ononsegmented cranial mesoderm ocranial neural crest oNonsegmented cranial mesoderm oMuscle cells oCranial neural crest oMuscle connective tissue (muscle coat) Sefton and Kardon, 2019. Curr Top Dev Biol Extraocular muscles Randolph and Pavlath, 2015 Cranial mesoderm Developmental defects of eye Bi6140 Embryology 48 oMicrophthalmia oCongenital eye defect oSmall and insufficiently developed eye oDefect in formation of optic vesicle oUnilateral or bilateral oAnophthalmia oCongenital eye defect oMissing eye, ultrasound often reveals rest of the eye basis inside the head oDefective formation of optic vesicle oUnilateral or bilateral Obsah obrázku osoba, dítě, interiér, vysoký Popis byl vytvořen automaticky Obsah obrázku osoba, zubní kartáček, mladý, štětec Popis byl vytvořen automaticky EAR ◦ 49 Human ear | Structure, Function, & Parts | Britannica Development of ear 50 oEar formed of 3 parts: oexternal – auricle, external canal omiddle – middle ear cavity, Eustachian tube, bones and muscles oinner – saccule, cochlea, organ of Corti oEar basis develops: oin region of pharyngeal arches and hindbrain oformation of ectodermal thickening (ear placode) oplacode – basis for development of inner ear Anthwal and Thompson, 2015. J Anat Otic placode Pharyngeal arches Lens placode Invaginating neural tube Otic placode Development of inner ear Bi6140 Embryology 51 Moore and Persaud. The developing Human 8e oformation of ectodermal thickening in the hindbrain region – otic placode oepithelial cells of otic placode start to invaginate to mesenchyme around hindbrain – formation of otic pit oOtic pit separates from surface ectoderm – formation of hollow structure lined by cylindrical epithelium – otic vesicle, cavity filled with endolymph oOtic vesicle localized in region between surface ectoderm covered by mesenchymal cells – ear capsule osome epithelial cells – leave vesicle and form sensory ganglia of VIII. cranial nerve (vestibulocochlear) Optic groove Neural ridge Otic placode Otic placode section hindbrain Surface ectoderm mesenchyme section Otic placode Otic pit Otic placode Neural tube section Formation of otic vesicle Surface ectoderm Otic vesicle Otic vesicle Differentiation of otic vesicle 52 ofrom otic vesicle – formation of membranous labyrinth lined with epithelium oepithelium differentiation – regions with different thickness of epithelium oOtic vesicle divides into 2 parts: odorsal – utricular (vestibular basis – vestibular/balancing system) oventral – saccular (inner ear basis – hearing) odorsomedial – evagination leads to formation of endolymphatic duct, with terminal extension – endolymphatic vesicle (regulation of volume and pressure of endolymph) saccule Cochlear canal Utricular part (developing semicicular duct) Edited: McGeady et al. Veterinary Embryology. 2009 Development of vestibular system 53 ofrom dorsal utricle - semicircular ducts oFormation of 3 semicircular ducts: o2 vertically oriented o1 oriented under 90 O angle to vertical ducts oat the end of each canal - extension called ampullae containing sensory organs Semicircular ducts Edited: McGeady et al. Veterinary Embryology. 2009 Development of cochlear system 54 ofrom ventraly oriented saccule formation of evagination – cochlear duct oduct first prolongates and narrows and later convolutes oadjacent mesenchyme – differentiation to auditory cartilage Edited: McGeady et al. Veterinary Embryology. 2009 Obsah obrázku text Popis byl vytvořen automaticky ductus reuniens onarrow duct connecting saccule and cochlear duct – ductus reuniens Development of cochlear system 55 opart of cartilage adjacent to basillary membrane is vacuolated oformation of cavity between outer cartilaginous layer and membranous labyrinth – perilymphatic space filled with perilymph oPerilymphatic space divided to: oScala vestibuli – cochlear duct separated by vestibular membrane oScala tympani – cochlear duct separated by basilar membrane ocartilaginous labyrinth ossify – formation of bony labyrinth omigration of cells from medial sac wall medialy – formation of statoacoustic ganglion (together with neural crest cells) Edited: McGeady et al. Veterinary Embryology. 2009 Endolymphatic vesicle Semicircular canal ampullae saccule ductus reuniens Cochlear duct Cochlear duct cartilage Basilar membrane odifferentiation of basal cells in cochlear duct – formation of organ of Corti Vestibular membrane scala vestibuli Cochlear duct Nerve fibers ganglion scala vestibuli Organ of Corti scala vestibuli Cochlear duct scala tympani developing organ of Corti Development of middle ear 56 oTympanic cavity, Eustachian tube, bones and muscles oEpithelium of 1. pharyngeal arch pouch (endoderm) oTympanic cavity oEustachian tube omiddle ear ossicles – mesenchyme of pharyngeal arches epitel 1. faryngeální výchlipky Epithelium of 1. pharyngeal pouch epithelium of 1. pharyngeal cleft Basis of malleus and incus Basis of stapes Tympanic cavity Eustachian tube Development of middle ear ossicles 57 oMalleus, incus and stapes develop from 1. and 2. pharyngeal arches o1. pharyngeal arch – endochondral ossification of Meckel`s cartilage: oMalleus oincus o2. pharyngeal arch – endochondral ossification of Reichert cartilage: ostapes Scott Gilbert. Developmental Biology 10th edition Meckel`s cartilage malleus incus stapes Reichert cartilage Development of external ear 58 oexternal canal, auricle, tympanic membrane oepithelium of 1. pharyngeal arch cleft (ectoderm) oExternal auditory canal opartly tympanic membrane and auricle oproliferation of pharyngeal cleft cells – formation of transitional epithelial plug of ear canal - meatal plug oectodermal wall get to contact with endodermal wall, separated by thin mesenchymal layer – basis for formation of tympanic membrane oin human – external ear (auricle) develops from mesenchyme of 1. and 2. pharyngeal arch covered by ectoderm – basis for 6 auricular swellings Edited: McGeady et al. Veterinary Embryology. 2009 meatal plug Developing external auditory canal Developing external auditory canal Developmental defects of ear 59 oAnotia/microtia oInsufficient development of auricle and external auditory canal oAnotia – complete missing of external ear (rare) oMicrotia – small insufficiently developed ear oCochlear aplasia/hypoplasia oAltered development of middle ear labyrinth and adjacent structures oAplasia – complete absence of cochlear and vestibular apparatus oHypoplasia – smaller cochlear and vestibular apparatus NOSE ◦ 60 Topic Image Development of nasal cavity 61 oformation of nasal placodes – ectodermal thickening, epithelium growth and mesenchymal proliferation around placodes oPlacode deepening – formation of nasal pit, lateral nasal processes on sides, medial nasal processes are formed later odeepening and extension of nasal pit – nasal groove odeepening of nasal groove, approaching stomodeum – formation of nasal sac Som and Naidich, 2013. Am J Neurorad Medial nasal processes Separation of primitive nasal and oral cavities 62 omaxillary prominences grow medially – nasal sacs are pushed medially omedial nasal prominence form intermaxillary segment oclosing space between maxillary and medial nasal prominences – buconasal groove disappears → closing of the nasal sac lower part oprimitive nasal and oral cavities separated Obsah obrázku klipart Popis byl vytvořen automaticky Som and Naidich, 2013. Am J Neurorad Formation of nasal and oral cavities 63 oprimitive nasal cavity epithelium grows to underlying mesenchyme – formation of oronasal membrane (connection of primitive nasal and oral epithelium) odifferentiation of the olfactory epithelium dorsally ooronasal membrane breakdown ocommunication between oral and nasal cavitites through primitive choana osecondary palate formed from maxillary prominences, definitive choana formed caudally McGraw-Hill, 2006 brain epithelium oral cavity Differentiation of olfactory epithelium 64 odorsal part of nasal cavity – differentiation of olfactory epithelium o2 sources: oectoderm – sensory bipolar neurons, basal epithelial cells oneural crest – ensheathing supporting cells oSensory bipolar neurons: o1. outgrowth – nasal cavity o2. outgrowth – axon leading to olfactory lobe in brain obasal epithelial cells – stem cells of sensory olfactory neurons (basis for recovery of sensory neurons) oSupporting cells – glial cells of sensory olfactory neurons Developmental defects of olfactory epithelium 65 oAnosmia/hyposmia oAltered development of olfactory epithelium oMostly no differentiation of olfactory epithelium oDefective communication between epithelium and brain oCan be also caused by infections – ability to regenerate oAnosmia – complete absence of olfactory epithelium oHyposmia – partial defect in olfactory epithelium differentiation TASTE ◦ 66 Anatomy of Taste, Illustration - Stock Image - F031/7042 - Science Photo Library Development of taste system 67 oformation of taste placodes – cylindrical cells in cubic tongue epithelium – invagination to underlying mesenchyme – taste papilla oepithelial placodal cells in papilla differentiate to sensory cells and form taste buds ocells in placode and adjacent epithelial cells undergo morphogenesis which give rise to morphologically diverse taste papilla: ocircumvallate – posterior tongue ofoliate – lateral tongue ofungiform – anterior tongue otaste papilla – mesenchymal basis covered by epithelium Kramer et al. 2019 Chandrashekar et al. 2016. Nature Cells forming taste bud 68 otaste buds localized in multilayered epithelium, taste bud connected with oral cavity through taste pore oReceptor cells – individual types of receptor taste cells, connected to afferent sensory nerve fibers, differentiate from ectoderm oSupport cells – glia-like cells covering receptor cells omost numerous odevelops from precursors originating in neural crest oBasal cells – stem cells of taste buds – ability to recover taste cells Pagella et al. 2014. Cell Mol Life Sci INTEGUMENT ◦ 69 1,615 Integument Images, Stock Photos & Vectors | Shutterstock Functions of skin 70 oformation of outer layer of individuals body and other structures (hair, fingernails, feathers) oFormation of protective layer with multiple functions: obarrier against physical, chemical, mechanical and biological factors otermoregulation osecretion oimmune response opigmentation Origin and development of skin and its derivatives Bi6140 Embryology 71 omain source for development of external surface: oepidermis - ectoderm Introduction to Anatomy and Development, University College London Green et al. 2015. Nature Epidermis development 72 oepidermis – outer layer of skin ocuboidal epithelium, basal membrane in contact with mesenchyme oafter neurulation – 2 layers: oBasal layer – cuboidal epithelium, mitotically active operiderm – flat cells on surface, first differentiation of basal cells, cover developing body oBasal cells proliferate – formation of intermediate layer – onset of multilayered epidermis formation oBasal layer cells differentiate into cells specific for individual layers oduring differentiation – peridermal cells detach from epidermis surface Edited: McGeady et al. Veterinary Embryology. 2009 Periderm detachment Epidermis development 73 odifferentiation of basal cell layer below the periderm – formation of epidermis layers: ostratum basale ostratum spinosum ostratum granulosum ostratum corneum odifferentiation of basal cells induced by factors produced in underlying mesenchyme (mesoderm) – formation of keratinocytes in epidermis (keratin production) oformation of keratinizing multilayered squamous epithelium omelanoblasts migration (neural crest) to forming epidermis – formation of melanocytes (pigment production), or migration of Schwann cell precursors (also formation of melanocytes) Edited: McGeady et al. Veterinary Embryology. 2009 Keratinizing layer Intermediate layer Basal layer Basal lamina dermis Migration – important mechanism for development of diverse tissues and organs 74 ◦free migration – small body size (earlier then E12 stage), cells migrate efficiently perineural migration – large body size (later then E12 stage), cells do not migrate efficiently – participation of nerves Furlan and Adameyko, 2018 Schwan cell precursors (SCPs) – migrating precursors for different cell types Epidermal layers 75 oStratum basale – cuboidal to cylindrical cells, stem cells and keratinocytes, melanocytes, proliferating cell layer - regeneration of epidermis oStratum lucidum – tightly connected keratinocytes without nuclei and organeles oStratum granulosum – multiple layers of flat keratinocytes, contain keratohylian granules oStratum spinosum – the thickest layer formed of kerytinocytes, in deeper layers proliferating cells, cells produce keratin fibers and flatten oStratum corneum – multiple layers of dead keratinizing cells, formation of durable and strong surface Dermis development 76 odermis – layer underlying the epidermis oFormed from different sources: oparaxial mesoderm – basis for dermis formation in trunk region osomatic lateral plate mesoderm – basis for dermis development in trunk and limbs oCranial neural crest – basis for dermis in head region omesenchymal cells of dermis differentiate to fibroblasts (connective tissue cells) ofibroblasts produce collagen and elastic fibers osurface papillary layer – loose connective tissue ounderlying reticular layer – dense connective tissue, large amount of collagen and elastic fibers olocalization of nerves, vessels, glands and hair follicles Obsah obrázku mapa Popis byl vytvořen automaticky Developmental defects of skin Bi6140 Embryology 77 oCongenital skin aplasia (aplasia cutis congenita) ocongenitally missing skin olocal or the whole surface oThe most often - missing skin on head opatogenesis not clear – caused by drug use and other substances during pregnancy oinsufficient closure of surface ectoderm Obsah obrázku osoba, interiér, zavřít Popis byl vytvořen automaticky Obsah obrázku interiér, osoba, patro Popis byl vytvořen automaticky oCephalocele opermeation of intracranial structures through opening in the skull ocaused by insufficient separation of neuroectoderm from surface ectoderm oformation of sac filled with neural tissue covered by skin Origin and development of hair follicle Bi6140 Embryology 78 oOrigin of hair follicle: obasal layer of epidermis (ectoderm) grows through the underlying mesenchyme (dermis - mesoderm or neural crest) oformation of hair follicle ostages: oepidermal placode ohair bud ohair bulb ohair cone ohair Developmental stages of hair 79 oformation of epidermal thickening - placode in epidermis oepidermal placode cells rearrange, proliferate and invaginate to underlying mesenchyme – formation of hair bud omesenchymal cells condensate around the bud region – bud prolongation, mesenchymal cells surrounded by epithelial (hair papilla) – formation of hair bulb oHair papilla – germ cells, matrix cells, melanocytes oHair papila induces formation of inner epidermal cells – formation of germinal matrix: oHair fiber oepithelial root sheet oformation of cavity in hair bulb – connection of germinal matrix and surface Edited: McGeady et al. Veterinary Embryology. 2009 Epidermis proliferation mesenchyme Hair papilla Epidermis proliferation Hair papilla Root of hair Germinal matrix Developmental stages of hair 80 oouter epidermal cells line the cavity – outer hair sheet, localization of Bulge – hair follicle stem cells ogerminal matrix cells – proliferate and transfer to cavity in outer hair sheet – keratinization of cells and formation of hair fiber ocontinuous proliferation of basal cells in matrix cause pushing of the hair fiber towards the surface osurrounding mesenchyme: oconnective tissue osmooth muscles – arrector hair fiber muscle oinvagination of basal epidermal layer in hair region: osebaceous glands osweat glands Edited: McGeady et al. Veterinary Embryology. 2009 Hair papilla epidermis B Hair life cycle 81 opostnatal – changing proliferation and resting phases: oanagen oActive growth oProliferation of papillary cells okatagen oregression stage (recess) oproliferation in papilla is inhibited ohair root changed – club-shape otelogen oouter epidermal cells constriction in hair root region ohair follicle attached by strands of epithelial cells to recessing papilla orenewed anagen oformation of replacement hair oepithelial strands – formation of renewed hair bulb surrounding new hair papilla oold hair pushed out by replacement hair Edited: McGeady et al. Veterinary Embryology. 2009 anagen katagen telogen renewed anagen Developmental defects of hair 82 oCongenital hypotrichosis ohair absence during fetal period – often during whole life oisolated defect, no other skin defects ocaused by mutations in genes important for growth, proliferation and differentiation of hair bulb cells oCongenital hypertrichosis oalso called Werewolf syndrome ooverproduction of hair due to formation of more hair follicles ooften fetal hair preserved ocaused by mutation in genes responsible for formation and growth of hair follicles omutations often caused by drug use during pregnancy (antibiotics, anti-inflammatory drugs, immunosuppressive drugs) Romero and Grimalt, 2014. Shah et al. 2018. Ind J Dermatol Vener Leprol Origin and development of feathers 83 Dermal condensation epidermis Dermal papilla Early fibers (barbs) Medullar cavity Broken feather sheat ointeraction of epithelial thickening (epidermis – ectoderm) with condensing dermal cells (mesoderm, neural crest) oformation of conical papilla – epidermal surface, underlying dermal papilla odermal papilla continuously push out covering epidermis – formation of basic feather bud oinvagination of epidermal cells at the base of feather bud into dermis – formation of follicles covered with epidermis (ectoderm) Fibers (barbs) basis Feather sheat Dermal medulla Basis of follicle Edited: McGeady et al. Veterinary Embryology. 2009 ofollicle prolongation – feather bud tips start to form protrusions of follicles (fibers/barbs basis) oDown feathers – basal cells in papilla proliferate – formation of epithelial colar, formation of cellular protrusions to medullary cavity oseparation of protrusions and keratinization – formation of individual fibers Origin and development of feathers 84 ocontour feathers – early development identical with down Edited: McGeady et al. Veterinary Embryology. 2009 developing barbs epidermal collar epidermal sheath developing shaft barb ridges barbs shaft (main axis) epidermal collar oformation of epidermal collar at the base of developing bud oproliferation in the surface collar region – formation of basis for shaft (axis) of feather – prolongation towards distal part of bud osmaller barbs outgrow from main shaft on both sides – basis for vane bud crown of barbs epidermis epidermal colar Development of fingernail 85 oboth sides from the nail field – lateral nail folds – overgrow nail field, connected to proximal nail fold Cui et al. 2013. J Investig Derm proximal nail fold lateral nail folds ounder the proximal nail fold – formation of nail matrix – production of nail-forming material onail matrix cells are keratinizing – formation of nail plate onail plate grows distally over the nail bed towards the end of finger Developmental defects of fingernail 86 oCongenital anonychia opartial or total absence of fingernails on feet and/or hands ocaused by defects in nail matrix formation or inability to produce material for nail formation Khan et al. 2015. Br J Dermatol Etensel et al. 2002. Eur J Plast Surg Origin and development of scales in bony fish 87 Sire and Akimenko, 2004. In J Dev Biol oleptoid/elasmoid scales – concentrically shaped scales formed of 4 layers: osurface layer – formed of epidermis, almost the whole surface ozebrafish (Danio rerio) – formation of leptoid scales – the most often scale type oelasmodin – deepest layer, not completely mineralized, formed of collagen fibers in layers (plywood look) oExternal layer – thin well mineralized layer formed of collagen fibers oLimiting layer – highly mineralized layer with no collagen fibers Origin and development of scales in bony fish 88 Sire and Akimenko, 2004. In J Dev Biol olate morphogenesis – accumulation (condensation) of mesenchymal cells in scale papilla oearly differentiation – upper layers of papilla differentiate to scale-forming cells, accumulation of first scale parts between papilla-forming cells – external layer olate differentiation – deeper layers of papilla under the external layer differentiate to elasmoblasts – production and accumulation of elasmodin obending and invagination – epidermis bends around posterior part of developing scale – formation of overlay over the next scale, in anterior part invagination of scale to dermis Scale papilla External layer elasmodin elasmoblasts Fun facts ◦How quick is the transfer of infos in the brain? ◦How many watts can brain generate? ◦If eye would be a camera, what woudl be its resolution? ◦When ear lobe stop growing? 89 7000 m/s 23W 576 mega pixels