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2a embryonic development
- 1. Survey of Embryonic Development
- 2. Human Anatomy andPhysiology, 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 Embryo 3-week embryo 4-week embryo 5-week embryo 6-week embryo 7-week embryo 8-week embryo 9-week fetus 12-week fetus
- 3. Sperm nucleus Acrosome Acrosomal reaction Granulosa cells of corona radiata Zona pellucida Extracellular space Oocyte plasma membrane Cortical granule 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 Sperm Corona radiata Zona pellucida First polar body Fusion of oocyte and sperm plasma membranes Cortical reaction Sperm nucleus engulfed by oocyte cytoplasm Oocyte cytoplasm Oocyte in second meiotic division (a) (b)
- 4. (a) Human Anatomyand 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 Extracellular space Second meiotic division of oocyte Second meiotic division of first polar body Detached sperm tail Sperm pro-nucleus Ovum nucleus Sperm and ovum chromosomes Zygote Male pronucleus Mitotic spindle Centriole Female pronucleus Polar bodies Corona radiata Zona pellucida (b) (c) (d) (e) (f) (g) (h)
- 5. (a) (b) (c)(d) (e) Sperm Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Degenerating zona pellucida Blastocyst cavity 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 Uterus Ovulation Endometrium Cavity of uterus Ovary Fertilization (sperm meets egg) Uterine tube Oocyte (egg) (a) (b) (c) (d) (e) Cleavage from zygote to blastocyst
- 6. 0 4 812 16 20 24 28 32 36 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. (a) Human Anatomyand Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Implantation of the blastocyst Endometrium Uterine endometrial epithelium Inner cell mass Trophoblast Blastocyst cavity Lumen of uterus Endometrial stroma with blood vessels and glands Syncytiotrophoblast Cytotrophoblast Inner cell mass (future embryo) Lumen of uterus (b) (c)
- 8. Human Anatomy andPhysiology, 7e by Elaine Marieb & Katja Hoehn Future opening between mouth and pharynx Head Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Formation of the three primary germ layers Bilayered embryonic disc Amniotic sac Yolk sac Amniotic sac (amnion) Yolk sac Cut edge of amnion Left Tail Primitive streak Hypoblast Right Epiblast Yolk sac (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
- 9. Human Anatomy andPhysiology, 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) Left Right Sections Tail Primitive streak Primitive streak Endoderm Mesoderm Definitive endoderm Epiblast Hypoblast Ectoderm (f) Bilayered embryonic disc, superior view (g) 14–15 days (h) 16 days
- 10. Head Human Anatomyand Physiology, 7e by Elaine Marieb & Katja Hoehn Neural Neural groove fold 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 Surface ectoderm Tail Yolk sac Cut edge of amnion Primitive streak Neural plate Future neural crest Notochord Notochord Cut edge of amnion Neural plate Primitive node Primitive streak Neural groove Neural crest Left Right
- 11. Tissues derived fromthe 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 andPhysiology, 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: Chorionic villus • Ectoderm 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) 71/2-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. Events of placentation,early embryonic development, and extraembryonic membrane formation Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Decidua basalis Maternal blood Chorionic villus Umbilical blood vessels in umbilical cord Amnion Amniotic cavity Yolk sac Extraembryonic coelom Chorion Decidua capsularis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Lumen of uterus (d) 41 / 2 - week embryo
- 15. Extraembryonic coelom HumanAnatomy 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
- 16. Maternal blood inlacuna (intervillus space) 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 Umbilical cord (g) Stratum basalis of endometrium Maternal portion of placenta (decidua basalis) Fetal portion of placenta (chorion)