Anatomy Physiology SIXTH EDITION Chapter 29 part 1

Anatomy & Physiology SIXTH EDITION Chapter 29, part 1 Development and Inheritance Power. Point® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Frederic H. Martini Fundamentals of

Learning Objectives • Explain the relationship between differentiation and development and specify the various stages of development • Describe the process of fertilization • List the three prenatal periods and describe the major events associated with each • Discuss the importance of the placenta as an endocrine organ Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Learning Objectives • Discuss the structural and functional changes in the uterus during gestation • List and discuss the events that occur during labor and delivery • Relate basic principles of genetics to the inheritance of human traits Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

SECTION 29 -1 An Overview of Topics in Development Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Differentiation and development • Development • Gradual modification of physical and physiological characteristics • Differentiation • The creation of different types of cells Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Stages of development • Prenatal development • Embryological • Changes occurring the first two months after fertilization • Fetal • Begins at the start of the ninth week and continues until birth • Postnatal development • Commences at birth and continues to maturity Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

SECTION 29 -2 Fertilization Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Fertilization (conception) • Occurs in the uterine tubes • Within a day of ovulation • Spermatozoa cannot fertilize an ovum until after capacitation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 29. 1 Fertilization Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 1 a

Figure 29. 1 Fertilization Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 1 b

The Oocyte at Ovulation • Oocyte is in meiosis II • Surrounded by the corona radiate • Spermatozoa release hyaluronidase and acrosin • Enzymes required to penetrate corona radiate • Single spermatozoan contacts oocyte, fertilization begins • Oocyte activation PLAY Animation: Fertilization and Oocyte Activation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Oocyte activation • Oocyte completes meiosis II • Functionally mature ovum • Female pronucleus and male pronucleus fuse (amphimixis) • Polyspermy prevented by membrane depolarization and cortical reaction Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

SECTION 29 -3 The Stages of Prenatal Development Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Embryonic and Fetal Periods • Induction • During prenatal development differences in cytoplasmic composition trigger changes in genetic activity • Gestation periods • Three trimesters Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

SECTION 29 -4 The First Trimester Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

The First Trimester • Cleavage • Zygote becomes a preembryo then a blastocyst • Implantation • Blastocyst burrows into uterine endometrium • Placentation • Blood vessels form around blastocyst and placenta develops • Embryogenesis • Formation of a viable embryo Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Cleavage and blastocyst formation • A series of cell divisions that subdivides the cytoplasm of the zygote • Trophoblast – outer layer of cells • Inner cell mass – cluster of cells at one end of blastocyst Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 29. 2 Cleavage and Blastocyst Formation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 2

Implantation • Occurs about 7 days after fertilization • Trophoblast enlarges and spreads • Maternal blood flows through open lacunae • Gastrulation • Embryonic disc composed of germ layers • Endoderm • Mesoderm • Ectoderm Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 29. 3 Stages in Implantation PLAY Animation: Location of the Endometrium Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 3

Figure 29. 4 The Inner Cell Mass and Gastrulation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 4

Germ layers • Gastrulation • By day 12 surface cells move toward the primitive streak • A third germ layer forms • The three germ layers are: • Ectoderm – superficial cells that did not migrate • Endoderm – cells facing the blastocoele • Mesoderm – migrating cells between ectoderm and endoderm Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Extraembryonic Membranes • Four extraembryonic membranes: • Yolk sac • Amnion • Allantois • Chorion Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 29. 5 Extraembryonic Membranes and Placenta Formation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 5 a, b

Figure 29. 5 Extraembryonic Membranes and Placenta Formation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 5 c, d

Figure 29. 5 Extraembryonic Membranes and Placenta Formation Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 5 e

Embryo Anatomy • Yolk sac • Important site of blood cell formation • Amnion • Encloses fluid that surrounds and cushions developing embryo • Allantois • Eventually becomes bladder • Chorion Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 29. 6 A Three-Dimensional View of Placental Structure Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 29. 6 a

Placentation • Chorionic villi extend into maternal tissue • Forms intricate branching network for maternal blood • Umbilical cord connects fetus to placenta Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Hormones of the placenta • Trophoblast secretes hormones to maintain pregnancy • HCG • Estrogens • Progesterone • h. PL • Placental prolactin • relaxin Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings