1、DHS 2General EmbryologyLecture 1Original Lecture: Prof. Grant Townsend, University of AdelaideDr. Sausan Al Kawas University of SharjahCopyright 2006/07 The University of Sharjah slide 2ObjectivesTo provide a general description of human embryological processes as follows: Germ cell formation & fert
2、ilization Prenatal development Induction, competence, and differentiation Formation of three-layerd embryo Formation of neural crest Formation of human tissues Folding of the embryoCopyright 2006/07 The University of Sharjah slide 3Embryology Embryology is literally “the study of the embryo” More ge
3、nerally it refers to “the study of prenatal development” Embryo = 2-8 weeks Foetus = 9 weeks to birthUNSW Embryology 2007Copyright 2006/07 The University of Sharjah slide 4Embryology Ontogeny : stages of development of an individual Teratology : study of abnormal development (congenital malformation
4、s)UNSW Embryology 2007Copyright 2006/07 The University of Sharjah slide 5Mitosis and MeiosisCopyright 2006/07 The University of Sharjah slide 6Gametogenesis Gametogenesis is a process of formation and development of male(sperm) and female (ovum)gametes. During this process a reduction of the the num
5、ber 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 7Gametogenesis It also involves the chromosomal and the cytoplasmic changes. These alteration of the shape of the primary
6、 germ cells allow them to become ready for fertilization. Copyright 2006/07 The University of Sharjah slide 8Gametogenesis 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 be
7、come larger as a result of increase in the a mount of their cytoplasm and called ovum.Mature spermMature oocyteCopyright 2006/07 The University of Sharjah slide 9Fertilization The fertilization occur when sperm contacts an ovum to form a zygote in the uterine tube. The zygote, which contains 46 chro
8、mosomes, 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 AnatomyCopyright 2006/07 The University of Sharjah slide 10These images reproduced from Dr. Di MarzoGeneral EmbryologyMature Human EggFertilized Human Zygote 4 Cell Human EmbryoUNSW Embryology 2010
