IntroEmb_BOH [2024].ppt

Introduction to Embryology Dr Helen Ritchie School of Medical Sciences The University of Sydney Page 1 Last updated 11 June 2024  COMMONWEALTH OF AUSTRALIA Copyright Regulation WARNING This ma...

Introduction to Embryology Dr Helen Ritchie School of Medical Sciences The University of Sydney Page 1 Last updated 11 June 2024  COMMONWEALTH OF AUSTRALIA Copyright Regulation WARNING This material has been reproduced and communicated to you by or on behalf of the University of Sydney pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice  Periods of development Embryonic period – 0-8 weeks – Establishment of organ systems Foetal period – 9 weeks to term – Growth and maturation of organ systems The University of Sydney Page 3  Week 1 Fertilisation takes places in uterine tube = day 0 or 2 weeks LMP Union of genetic material in sperm and ovum The University of Sydney Page 4  Week 1: Fertilization to blastocyst formation Zona pellucida Morula: compact embryo formed through cell division Zona pellucida: is a layer of glycoprotein that prevents implantation Blastocyst: first of The University differentiation Sydney of the embryo. Page 5  Week 1: Fertilization to blastocyst formation Embryo is at the blastocyst stage Differentiated into: Inner cell mass (embryo) trophoblast (placenta) In vitro fertilization follows similar process. Embryos at blastocyst stage are cultured until this stage and implanted at the end of week 1. The University of Sydney Page 6  Week 2: implantation to bilaminar disc Week 2: Zona hatching Implantation Bilaminar formation Epiblast Hypoblast The University of Sydney Page 7  Week 3: gastrulation Gastrulation: Epiblast differentiation into three germ layers: Ectoderm Mesoderm Endoderm. Electron microscopic image The University of Sydney Page 8 Week 3: Trimlaminar embryo Outer layer (ectoderm) ectoderm Skin, brain + spinal cord notochord Middle layer (mesoderm) muscle, connective tissue (blood, bone), endoderm mesoderm cardiovascular system (functional end of 3rd week), kidney, gonads Inner layer (endoderm) lines viscera, organs of gastrointestinal tract (liver, pancreas) The University of Sydney Page 9 Week 3: gastrulation Fate of the 3 germ layers in orofacial region: ectoderm notochord Endoderm: submandibular and sublingual glands Mesoderm: heart and vascular tissues, muscle (e.g. masticatory, expression), bone and other endoderm mesoderm connective tissue. Ectoderm: parotid gland and enamel – via dermal ectoderm; dentine/pulp and supportive structure— via neural crest; cranial nerves, taste buds. Notochord forms The University of Sydney Page 10  Week 3: Neural tube Formation neural groove neural crest neural groove neural crest neural fold neural fold notochord Day 19 The University of Sydney Page 11  Week 3: Neural tube Formation Day 20 The University of Sydney Page 12  Week 3: Neural tube Formation Day 22 The University of Sydney Page 13  Week 3: Neural tube Formation anterior neuropore Closes Day 24 somites Day posterior neuropore Closes Day 26 23 The University of Sydney Page 14  Week 3: Neural tube Formation Human Age: 23 days; Human Age: 22 days; Transverse cut Transverse cut Neural crest cells Following the closure of the trunk neural folds, the neural crest cells migrate from the dorsal aspect of the neural tube and become mesenchymal cell type. Later give rise to teeth and support structures The University of Sydney Page 15 Week 4: Caudal body folding Developing brain heart oro-pharyngeal membrane Day The University of Sydney Page 16 18 Colouring Book of Embryology G. Matsumura, Mosby 1992  Week 4: Caudal body folding Brain oro-pharyngeal membrane Day 23 The University of Sydney Colouring Book of Embryology G. Matsumura, Mosby 1992 Page 17  Week 4: Caudal body folding oro-pharyngeal membrane Brai n Day 28 The University of Sydney Colouring Book of Embryology G. Matsumura, Mosby 1992 Page 18  Week 4: Ventral body folding Results in: gut endoderm internalization ventral body wall closure encasement of the fetus in extraembryonic membranes. The University of Sydney Page 19  18 20 22 days 23 28 The University of Sydney Page 20  Human embryo at 4w pharyngeal arches occipital somites cervical somites orelimb bud heart umbilicus Somite hindlimb bud block of mesoderm Forms muscle, bone The University of Sydney Page 21  Pharyngeal arch formation Day 23 Day 26 Day 28 Pharyngeal/visceral/branchial The University of Sydney Page 22 evelopment of pharyngeal arches Time of appearance I: D22 II, III: D24 IV, VI: D29 Contents muscle cartilage cranial nerves blood vessels The University of Sydney Page 23  Development of pharyngeal Arches The University of Sydney Page 24  Development of the pharynx Pharyngeal pouches form on the endodermal side between the arches pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. The University of Sydney Page 25 http://inside.ucumberlands.edu/academics/biology/faculty/kuss//courses/ Digestive%20system/PharynxDevelop1Parts.jpg Muscle superior somites invade pharyngeal arches somites I: masticatory muscles, mylohyoid, anterior belly of digastric, tensor tympani, TVP II: facial expression, posterior belly of digastric, stylohyoid, stapedius III: stylopharyngeus IV/VI: intrinsic laryngeal and pharyngeal The University of Sydney Page 26  Cartilage/bone ural crest cells from developing brain ade pharyngeal arches and form cartilage and cranial nerves Maxilla, mandible form later as membrane bones I: Meckel’s cartilage (mandible), Palatopterygoquadrate bar (part of sphenoid), malleus, incus II: stapes, part of hyoid, temporal bones III: part of hyoid IV+VI: larynx cartilage The University of Sydney Page 27  Pharyngeal arch cartilages The University of Sydney Page 28  Cranial nerves Neural crest cells from developing brain invade pharyngeal arches and form cartilage and cranial ne I: Trigeminal (V2, V3) II: Facial nerve (VII) III: glossopharyngeal (IX) IV+VI: vagus (X) The University of Sydney Page 29  Blood vessels Maxillary artery and external carotid artery : internal carotid I: common carotid V+VI: arch of the aorta The University of Sydney Page 30 Development of the Face The University of Sydney Page 31  Development of the face D24 frontonasal process maxillary process I stomatodeum mandibular process The University of Sydney Page 32  Development of the face D28 frontonasal process max proc nasal placode mouth mand proc II The University of Sydney Page 33  Development of the face D31 frontonasal process medial nasal proc eye nasal pit lateral nasal proc max proc mand proc The University of Sydney Page 34  Development of the face D35 frontonasal process medial nasal proc eye lateral nasal proc max proc mand proc The University of Sydney Page 35  Development of the face Adult face frontonasal process medial nasal proc max proc lateral nasal proc mand proc 10th Week The University of Sydney Page 36  Summary Nose –Nasal septum: Fused MNPs –Alae: Fused LNPs –Bridge: FNP Lips –Philtrum: fused MNPs –Upper lip: Maxillary process and MNP –Lower lip: fused mandibular processes The University of Sydney Page 37  Unilateral Macro (large)- cleft lip Micro (small)- stomia mouth Failure of fusion of Max Proc and Man Proc 10th Week The University of Sydney Page 38  Unilateral cleft lip Failure of fusion of MNP and Max Proc 10th Week The University of Sydney Page 39  Bilateral cleft lip Failure of fusion of MNP and Max Proc 10th Week The University of Sydney Page 40  Oblique facial cleft Failure of fusion of LNP and Max Proc 10th Week The University of Sydney Page 41  Median cleft lip Failure of fusion of MNP and MNP 10th Week The University of Sydney Page 42  Cleft lower lip Failure of fusion of MandP and MandP 10th Week The University of Sydney Page 43 Development of the Hard Palate The University of Sydney Page 44  Development of hard palate MNP tectal ridge/1°palate nasal septum Maxillar y process tongue palatal shelf/ 2 ° palate Fused MNP = tectal ridge Maxillary P = palatal shelf Adapted from: Langman’s Medical Embryology The University of Sydney 7 weeks TW Sadler Page 45  Development of hard palate Incisive foramen Elevation of palatal shelves Fusion with primary palate Tongue drops down Fusion occurs in AP 8 weeks direction in secondary Adapted from: Langman’s Medical Embryology TW Sadler palate The University of Sydney Page 46  Development of hard palate Upper 4 incisors nasal cavity nasal septum fused with palate tongue palatal soft palate: outgrowth of Oral cavity shelves posterior edge of palatal shelf fused 10 weeks Adapted from: Langman’s Medical Embryology The University of Sydney TW Sadler Page 47 https://embryology.med.unsw.edu.au/embryology/index.php/Palate_Development_2_Movie  Palate Fusion: 9th week Human gestation age 9th week Human gestation age 10th week Fusion of the palatal shelves with each other and with the nasal septum separates the nasal cavities from the oral cavity. The epithelial cells either undergo epithelial mesenchymal transformation or apoptosis to allow the fusion of the processes Ossification of the palate: in 8th week of intrauterine life, intramembranous ossification form the maxilla. The mid-palatal suture ossifies by 12-14 years. The University of Sydney Page 48 http://syllabus.med.unc.edu/ Malformations of the face and palate The University of Sydney Page 49  Facial clefts Orofacial clefts –1 in 700 Cleft lip with cleft palate –1 in 1600 Cleft palate w/o cleft lip –1 in 2800 –Males > female (2:1) –Occurs with another defect in third cases Cleft palate –1 in 1700 –female > male (2:1) The University of Sydney Page 50 http://www.keykidfoundation.org/facefix/KyranPalubon1d.jpg  Cleft involving primary palate Cleft anterior to incisive foramen Failure of fusion of palatal shelves with tectal ridge (cleft palate) Failure of fusion of MNP and Max process (cleft lip) Unilateral cleft lip and palate The University of Sydney Page 51 unilateral cleft of the primary palate  Cleft involving secondary palate – Cleft posterior to incisive foramen – Failure of fusion of palatal shelves Cleft of hard and soft palate The University of Sydney Page 52 http://b.thumbs.redditmedia.com/KunoLD4EUPFIo-W5.jpg  Cleft involving secondary palate Bifid uvula Cleft of Soft palate Failure of fusion of palatal shelves (late) – may indicate Failure of fusion of submucous cleft palatal shelves (early) The University of Sydney http://b.thumbs.redditmedia.com/KunoLD4EUPFIo-W5.jpg Page 53 https://embryology.med.unsw.edu.au/embryology/images/f/f6/Cleft_palate_001.jpg http://www.scielo.br/img/revistas/jaos/v15n3/a09f05.jpg  Submucous cleft – Involves hard or soft palate – Appears intact but there are muscle and bone deficits The University of Sydney Page 54 http://austinpublishinggroup.com/otolaryngology/fulltext/images/ajo-v1-id1011-g002.gif  Cleft involving secondary palate – Cleft posterior to incisive foramen – Failure of fusion of palatal shelves Cleft of hard and soft palate The University of Sydney Page 55 http://b.thumbs.redditmedia.com/KunoLD4EUPFIo-W5.jpg