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Survey of Embryonic Development. Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing.

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Presentation on theme: "Survey of Embryonic Development. Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing."— Presentation transcript:

1 Survey of Embryonic Development

2 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Diagrams showing the size of a human conceptus from fertilization to the early fetal stage Fertilization 1-week conceptus 2-week conceptus 3-week embryo Embryo 4-week embryo 5-week embryo 6-week embryo 7-week embryo 8-week embryo 9-week fetus 12-week fetus

3 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Sperm penetration and the cortical reaction (slow block to polyspermy Fusion of oocyte and sperm plasma membranes Cortical reaction Sperm nucleus engulfed by oocyte cytoplasm Oocyte cytoplasm Cortical granule Oocyte plasma membrane Extracellular space Zona pellucida Sperm nucleus Granulosa cells of corona radiata Acrosomal reaction Acrosome Oocyte in second meiotic division First polar body Zona pellucida Corona radiata Sperm (a) (b)

4 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Events immediately following sperm penetration Daughter cells Anaphase of first cleavage division Sperm and ovum chromosomes Zygote Male pronucleus Mitotic spindle Centriole Female pronucleus Polar bodies Ovum nucleus Sperm pro- nucleus Detached sperm tail Sperm Extracellular space Second meiotic division of oocyte Second meiotic division of first polar body Corona radiata Zona pellucida (a) (b) (c) (d) (e) (f) (g) (h)

5 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Blastocyst cavity Degenerating zona pellucida Inner cell mass Blastocyst cavity Trophoblast Zygote (fertilized egg) 4-cell stage 2 days Morula 3 days Early blastocyst 4 days Implanting blastocyst 6 days Cavity of uterus Uterus Endometrium Ovulation Ovary Fertilization (sperm meets egg) Uterine tube Oocyte (egg) Sperm (a)(b)(c)(d)(e) (a) (b) (c) (d) (e) Cleavage from zygote to blastocyst

6 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Hormonal changes during pregnancy Ovulation and fertilization Birth Human chorionic gonadotropin Progesterone Estrogens Gestation (weeks) Relavtive blood levels

7 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Implantation of the blastocyst Endometrial stroma with blood vessels and glands Syncytiotrophoblast Cytotrophoblast Inner cell mass (future embryo) Lumen of uterus Uterine endometrial epithelium Inner cell mass Trophoblast Endometrium Blastocyst cavity Lumen of uterus (b)(c) (a)

8 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Formation of the three primary germ layers Bilayered embryonic disc Amniotic sac Amniotic sac (amnion) Yolk sac Cut edge of amnion Left Right Primitive streak Hypoblast Epiblast Yolk sac Future opening between mouth and pharynx Head (b)... turned 90˚(c) 3-D view(d) Section view in (e) (a) Embryo (See Figure 28.7b) (e) Bilayered embryonic disc, lateral-superior view Yolk sac Tail

9 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Formation of the three primary germ layers Head Cut edge of amnion Yolk sac (cut edge) RightLeft Sections Tail Primitive streak Primitive streak Endoderm MesodermDefinitive endoderm Epiblast Hypoblast Ectoderm (f) Bilayered embryonic disc, superior view (g) 14–15 days (h) 16 days

10 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Neurulation (a) 17 days (b) 19 days Amnion Amniotic cavity Neural plate Ectoderm Mesoderm Notochord Endoderm Yolk sac Tail Head Cut edge of amnion Primitive streak Surface ectoderm Neural plate Future neural crest Notochord Cut edge of amnion Neural plate Primitive node Primitive streak Neural groove Neural fold Neural groove Neural crest LeftRight

11 Tissues derived from the three germinal layers Ectoderm: nervous tissues, epidermis and melanocytes. Mesoderm: bones, muscles, mesenchyme, reproductive system, urinary system. Endoderm: digestive system, respiratory system, endocrine system.

12 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Events of placentation, early embryonic development, and extraembryonic membrane formation Maternal blood vessels Lacuna (intervillus space) containing maternal blood Endometrium Amniotic cavity Primary germ layers: Ectoderm Chorionic villus Chorion Amnion Yolk sac Extraembryonic mesoderm Chorion being formed Lumen of uterus Proliferating syncytiotrophoblast Cytotrophoblast Amniotic cavity Bilayered embryonic disc: Epiblast Hypoblast Endometrial epithelium Mesoderm Endoderm Forming body stalk Allantois Extra- embryonic coelom (a) 7 1 / 2 -day implanting blastocyst (b) 12-day implanted blastocyst (c) 16-day embryo

13 Embryonic membranes Amnion: encases and protects embryo against mechanical and temperature trauma. Yolk sac: transfers nutrients to embryo. Replaced by placenta in humans. Allantois: repository of embryo wastes. Replaced by placenta in humans.

14 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Decidua basalis Maternal blood Chorionic villus Umbilical blood vessels in umbilical cord Amnion Amniotic cavity Yolk sac Extraembryonic coelom Chorion Decidua capsularis Lumen of uterus (d) 4 1 / 2 -week embryo Events of placentation, early embryonic development, and extraembryonic membrane formation

15 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Events of placentation, early embryonic development, and extraembryonic membrane formation Placenta Decidua basalis Chorionic villi Yolk sac Amnion Amniotic cavity Umbilical cord Uterus Lumen of uterus Decidua capsularis (f)13-week fetus Extraembryonic coelom

16 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Events of placentation, early embryonic development, and extraembryonic membrane formation Myometrium Maternal veins Maternal arteries Umbilical arteries Umbilical vein Connection to yolk sac Chorionic villus containing fetal capillaries Fetal arteriole Fetal venule Amnion (g) Umbilical cord Maternal blood in lacuna (intervillus space) Stratum basalis of endometrium Maternal portion of placenta (decidua basalis) Fetal portion of placenta (chorion)


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