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Anatomy & Physiology
SIXTH EDITION
Chapter 29, part 1
Development and Inheritance
PowerPoint® 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
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Differentiation and development
• Development
• Gradual modification of physical and
physiological characteristics
• Differentiation
• The creation of different types of cells
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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
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SECTION 29-2
Fertilization
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Fertilization (conception)
• Occurs in the uterine tubes
• Within a day of ovulation
• Spermatozoa cannot fertilize an ovum until after
capacitation
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Figure 29.1 Fertilization
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Figure 29.1a
Figure 29.1 Fertilization
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Figure 29.1b
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
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Embryonic and Fetal Periods
• Induction
• During prenatal development differences in
cytoplasmic composition trigger changes in
genetic activity
• Gestation periods
• Three trimesters
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SECTION 29-4
The First Trimester
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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
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Figure 29.2 Cleavage and Blastocyst Formation
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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
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Figure 29.3 Stages in Implantation
PLAY
Animation: Location of the Endometrium
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Figure 29.3
Figure 29.4 The Inner Cell Mass and
Gastrulation
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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
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Extraembryonic Membranes
• Four extraembryonic membranes:
• Yolk sac
• Amnion
• Allantois
• Chorion
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Figure 29.5 Extraembryonic Membranes and
Placenta Formation
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Figure 29.5a, b
Figure 29.5 Extraembryonic Membranes and
Placenta Formation
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Figure 29.5c, d
Figure 29.5 Extraembryonic Membranes and
Placenta Formation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 29.5e
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
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Figure 29.6a
Placentation
• Chorionic villi extend into maternal tissue
• Forms intricate branching network for
maternal blood
• Umbilical cord connects fetus to placenta
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Hormones of the placenta
• Trophoblast secretes hormones to maintain
pregnancy
• HCG
• Estrogens
• Progesterone
• hPL
• Placental prolactin
• relaxin
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings