embryology胚胎学

DHS 2General EmbryologyLecture 1,Original Lecture: Prof. Grant Townsend, University of Adelaide,Dr. Sausan Al Kawas University of Sharjah,Copyright 2006/07 The University of Sharjah,slide 2,Objectives,To provide a general description of human embryological processes as follows:Germ cell formation & fertilizationPrenatal developmentInduction, competence, and differentiationFormation of three-layerd embryoFormation of neural crestFormation of human tissuesFolding of the embryo,Copyright 2006/07 The University of Sharjah,slide 3,Embryology,Embryology is literally “the study of the embryo”More generally it refers to “the study of prenatal development”Embryo = 2-8 weeksFoetus = 9 weeks to birth,UNSW Embryology 2007,Copyright 2006/07 The University of Sharjah,slide 4,Embryology,Ontogeny : stages of development of an individualTeratology : study of abnormal development (congenital malformations),UNSW Embryology 2007,Copyright 2006/07 The University of Sharjah,slide 5,Mitosis and Meiosis,Copyright 2006/07 The University of Sharjah,slide 6,Gametogenesis,Gametogenesis is a process of formation and development of male(sperm) and female (ovum)gametes.During this process a reduction of the the number of chromosomes takes place from diploid number (46) of primary germ cells to the haploid number (23) in the mature germ cell.,Copyright 2006/07 The University of Sharjah,slide 7,Gametogenesis,It also involves the chromosomal and the cytoplasmic changes. These alteration of the shape of the primary germ cells allow them to become ready for fertilization.,Copyright 2006/07 The University of Sharjah,slide 8,Gametogenesis,The large rounded primary male germ cells, lose most of their cytoplasm and develop head, tail and neck to assist in the movement of the sperms.The rounded female germ cells become larger as a result of increase in the a mount of their cytoplasm and called ovum.,Mature sperm,Mature oocyte,Copyright 2006/07 The University of Sharjah,slide 9,Fertilization,The fertilization occur when sperm contacts an ovum to form a zygote in the uterine tube.The zygote, which contains 46 chromosomes, rapidly divide by mitosis to form mass of cells as 2,4, 8, 16, 32. This mass of cells continue dividing in order to give the different tissues then organs of the human body.,Ref: Dental Embryology, Histology, and Anatomy,Copyright 2006/07 The University of Sharjah,slide 10,These images reproduced from Dr. Di Marzo,General Embryology,Mature Human Egg,Fertilized Human Zygote,4 Cell Human Embryo,UNSW Embryology 2010,Copyright 2006/07 The University of Sharjah,slide 11,General Embryology,FertilizationZygoteGenotype, environment, phenotypeInduction, competence, differentiationFormation of the three layered embryoMorula, blastocyst, bilaminar then trilaminar germ discEctoderm, endoderm, mesodermFormation of neural crest cellsFolding of the embryo,Copyright 2006/07 The University of Sharjah,slide 12,Copyright 2006/07 The University of Sharjah,slide 13,.,General Embryology,Ref: Dental Embryology, Histology, and Anatomy,Copyright 2006/07 The University of Sharjah,slide 14,General Embryology,Ref: Dental Embryology, Histology, and Anatomy,Copyright 2006/07 The University of Sharjah,slide 15,Structure of the blastocyt (blastula):,Copyright 2006/07 The University of Sharjah,slide 16,Implantation of the blastocyte:,Copyright 2006/07 The University of Sharjah,slide 17,Formation of embryonic layers:,second week,Ref: Dental Embryology, Histology, and Anatomy,Copyright 2006/07 The University of Sharjah,slide 18,Formation of the tri-laminar disc:,Third week,Formation of primitive streak at the midline causing the disc to have right and left half, each half will be as mirror to the other,Copyright 2006/07 The University of Sharjah,slide 19,Formation of primitive streak,Formation of the tri-laminar disc:,UNSW Embryology 2007,Copyright 2006/07 The University of Sharjah,slide 20,Formation of the mesodermal layer:,Movement of some cells of epiblast toward hypoblast at the primitive streak forms a third embryonic layer called mesoderm.,Copyright 2006/07 The University of Sharjah,slide 21,Formation of Neural Crest,The nervous system develops as a thickening within ectoderm giving the neural plate.,Copyright 2006/07 The University of Sharjah,slide 22,Formation of Neural Crest,Neural plate: will fold to form neural grooveNeural groove: fuses to form neural tubeNeural tube: Gives rise to brain and spinal cord,Copyright 2006/07 The University of Sharjah,slide 23,Formation of Neural Crest,UNSW Embryology 2007,Copyright 2006/07 The University of Sharjah,slide 24,Ref: Human Anatomy & Physiology/ Marieb,Copyright 2006/07 The University of Sharjah,slide 25,Formation of Neural Crest,Neural crest cells migrate throughout the body and give rise to:Cranial and sensory ganglia and nervesSympathetic neuronesSchwann cellsPigment cellsMeningesCartilage of branchial archesMost of the connective tissue of the face “ectomesenchyme”,Ref: Avery (2003) Chapter 1992,Copyright 2006/07 The University of Sharjah,slide 26,Formation of Neural Crest,Neural crest is essential in development of the face, neck and oral tissues.All tissues of a tooth and its supporting structures, except enamel, are derived from neural crest cells,Ref: Avery (2003) Chapter 1992,Copyright 2006/07 The University of Sharjah,slide 27,The embryonic layers are distinct from each other and give rise to specific tissues such as:,Nervous system.,Sensory epi.of eye , ear & nose.,Epidermis, hair and nails.,Mammary & cutaneous glands.,Epi.of sinuses,oral & nasal cavities.,Intra-oral glands.,Tooth enamel.,Formation of the tissues:,Copyright 2006/07 The University of Sharjah,slide 28,Formation of the tissues:,Muscle tissue,C.T,Bone .,Cartilage.,Pulp.,Dentin .,Cementum.,PL.,Alveolar Bone .,Copyright 2006/07 The University of Sharjah,slide 29,