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PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 3 Copyright.

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Presentation on theme: "PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 3 Copyright."— Presentation transcript:

1 PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 3 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Embryology PART 1

2 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryology  Embryology – study of the origin and development of single individual  Prenatal period  Embryonic period – first 8 weeks  Fetal period – remaining 30 weeks

3 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Period Figure 3.1 (1 of 2)

4 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Fetal Period Figure 3.1 (2 of 2)

5 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Basic Body Plan  Skin – dermis and epidermis  Outer body wall – trunk muscles, ribs, vertebrae  Body cavity and digestive tube (inner tube)  Kidneys and gonads – deep to body wall  Limbs

6 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Basic Body Plan Figure 3.2

7 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Embryonic Period  Week 1 – from zygote to blastocyst  Conception – in lateral third of uterine tube  Zygote (fertilized oocyte) moves toward the uterus  Blastomeres – daughter cells formed from zygote  Morula – solid cluster of 12–16 blastomeres  “Mulberry”  Blastocyst – fluid-filled structure – ~ 60 cells

8 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Embryonic Period  Stages of first week  Zygote  4-cell  Morula  Early blastocyst  Late blastocyst (implants at this stage)

9 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Fertilization and the Events of the First 6 Days of Development Figure 3.3

10 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 2 – The Two-Layered Embryo  Bilaminar embryonic disc – inner cell mass divided into two sheets  Epiblast and the hypoblast  Together they make up the bilaminar embryonic disc

11 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 2 – The Two-Layered Embryo  Amniotic sac – formed by an extension of epiblast  Outer membrane forms the amnion  Inner membrane forms the amniotic sac cavity  Filled with amniotic fluid

12 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 2 – The Two-Layered Embryo  Yolk sac – formed by an extension of hypoblast  Digestive tube forms from yolk sac  NOT a major source of nutrients for embryo  Tissues around yolk sac  Gives rise to earliest blood cells and blood vessels

13 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Implantation of the Blastocyst Figure 3.4 (1 of 3)

14 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Implantation of the Blastocyst Figure 3.4 (2 of 3)

15 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Implantation of the Blastocyst Figure 3.4 (3 of 3)

16 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 3 – The Three-Layered Embryo  Primitive streak – raised groove on the dorsal surface of the epiblast  Gastrulation – a process of invagination of epiblast cells  Begins at the primitive streak  Forms the three primary germ layers

17 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 3 – The Three-Layered Embryo  Three Germ Layers*  Endoderm – formed from migrating cells that replace the hypoblast  Mesoderm – formed between epiblast and endoderm  Ectoderm – formed from epiblast cells that stay on dorsal surface *All layers derive from epiblast cells!

18 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Primitive Streak Figure 3.5e–h

19 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Notochord  Primitive node – a swelling at one end of primitive streak  Notochord forms from primitive node and endoderm  Notochord – defines body axis  Is the site of the future vertebral column  Appears on day 16

20 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Formation of the Mesoderm and Notochord Figure 3.6

21 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Neurulation  Neurulation – ectoderm starts forming brain and spinal cord  Neural plate – ectoderm in the dorsal midline thickens  Neural groove – ectoderm folds inward

22 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Neurulation  Neurulation (continued)  Neural tube – a hollow tube pinches off into the body  Cranial part of the neural tube becomes the brain  Maternal folic acid deficiency causes neural tube defects

23 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Neurulation  Neural crest  Cells originate from ectodermal cells  Forms sensory nerve cells  Induction  Ability of one group of cells to influence developmental direction of other cells

24 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Mesoderm Begins to Differentiate  Somites – our first body segments  Paraxial mesoderm  Intermediate mesoderm – begins as a continuous strip of tissue just lateral to the paraxial mesoderm

25 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Mesoderm Begins to Differentiate  Lateral plate – most lateral part of the mesoderm  Coelom – becomes serous body cavities  Somatic mesoderm – apposed to the ectoderm  Splanchnic mesoderm – apposed to the endoderm

26 PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 3 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Embryology PART 2

27 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Changes in the Embryo Figure 3.7a, b

28 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Changes in the Embryo Figure 3.7c, d

29 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape  Folding of embryo laterally and at the head and tail  Embryonic disc bulges; growing faster than yolk sac  “Tadpole shape” by day 24 after conception  Primitive gut – encloses tubular part of the yolk sac  Site of future digestive tube and respiratory structures

30 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape Figure 3.8

31 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape  Derivatives of the germ layers  Ectoderm forms  Brain, spinal cord, and epidermis  Endoderm forms  Inner epithelial lining of the gut tube  Respiratory tubes, digestive organs, and urinary bladder  Notochord – gives rise to nucleus pulposus within intervertebral discs

32 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape  Mesoderm – forms  Muscle  Bone  Dermis  Connective tissues (all)  Mesoderm differentiates further and is more complex than the other two layers

33 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Derivatives of Germ Layers Figure 3.10

34 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape  Mesoderm (continued)  Somites divides into  Sclerotome  Dermatome  Myotome  Intermediate mesoderm forms  Kidneys and gonads

35 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 4 – The Body Takes Shape  Mesoderm (continued)  Splanchnic mesoderm  Forms musculature, connective tissues, and serosa of the digestive and respiratory structures  Forms heart and most blood vessels  Somatic mesoderm – forms  Dermis of skin  Bones  Ligaments

36 PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 3 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Embryology PART 3

37 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Germ Layers in Week Four Figure 3.9a–d

38 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Week 5-8 – The Second Month of Embryonic Development  Limb buds form  Embryo first looks recognizably human (week 8)  Head is disproportionately large  All major organs are in place Figure 3.11

39 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Fetal Period  A time of maturation and rapid growth  Cells are differentiating during the first half of the fetal period  Normal births occur 38 weeks after conception  Premature birth is one that occurs before 38 weeks PLAY Ultrasound of Fetus

40 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Events of the Fetal Period Table 3.1 (1 of 3)

41 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Events of the Fetal Period Table 3.1 (2 of 3)

42 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Events of the Fetal Period Table 3.1 (3 of 3)


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