Human Anatomy Bio 11 Embryology “chapter 3” Stages of development 1. “Pre-” really early embryonic period: fertilization (egg + sperm) forms the zygote gastrulation [~ first 3 weeks] 2. Embryonic period: neurulation organ formation [~ weeks 3-8] 3. Fetal period: growth and maturation [week 8 – birth ~ 40 weeks] Human life cycle MEIOSIS • compare to mitosis • disjunction & non-disjunction – aneuploidy e.g. Down syndrome = trisomy 21 • visit http://www.ivc.edu/faculty/kschmeidler/Pages /sc-mitosis-meiosis.pdf • and/or http://www.ivc.edu/faculty/kschmeidler/Pages /HumGen/mit-meiosis.pdf GAMETOGENESIS We will discuss, a bit, at the end of the semester. For now, suffice to say that mature males produce sperm and mature females produce ova (ovum; egg) all of which are gametes Gametes are haploid which means that each gamete contains half the full portion of DNA, compared to somatic cells = all the rest of our cells Fertilization restores the diploid state. Early embryonic stages blastocyst (blastula) 6 days of human embryo development http://www.sisuhospital.org/FET.php human early embryo development https://opentextbc.ca/anatomyandphysiology/chapter/28- 2-embryonic-development/ https://embryology.med.unsw.edu.au/embryology/images/thumb/d/dd/Model_human_blastocyst_development.jpg/600px-Model_human_blastocyst_development.jpg Good Sites To Visit • Schmeidler: http://www.ivc.edu/faculty/kschmeidler/Pages /sc_EMBRY-DEV.pdf • https://embryology.med.unsw.edu.au/embryol ogy/index.php/Week_1 • https://opentextbc.ca/anatomyandphysiology/c hapter/28-2-embryonic-development/ Human Early Development https://embryology.med.unsw.edu.au/embryology/index.php/Blastocyst_Day_3-6_Movie zygote 2 - cell human embryo https://wrhhs.org/chapter-3-first-week-of-development/ https://embryology.med.unsw.edu.au/embryology/in HUMAN EARLY DEVELOPMENT dex.php?title=File:Human-oocyte_to_blastocyst.jpg Timing of susceptibility during development https://www.exposingtruth.com/air-pollution-londons-invisible-child-killer/fetaldev/ ovulation implantation implantation Formation of extra- embryonic membranes Gastrulation via primitive streak GASTRULATION formation of 3 germ layers gastrulation https://discovery.lifemapsc.com/library/review-of-medical-embryology/chapter-18- week-3-of-development-trilaminar-germ-disk-embryo-formation-and-gastrulation Folding of the embryonic disc neurulation https://discovery.lifemapsc.com/library/review-of-medical- embryology/chapter-20-week-3-of-development-intraembryonic-mesoderm- somite-development-and-the-intraembryonic-coelom Neurulation formation of the neural tube and somites https://en.wikipedia.org/wiki/Neurulation Derivatives of the 3 germ layers: ECTODERM MESODERM ENDODERM https://universe-review.ca/I10-13-layers.jpg …. AND THEN ….. https://www.hopkinsmedicine.org/healthlibrary/conditions/pregnancy_and_childbirth/first_trimester_85,P0 1218 …. FINALLY !.