Conception to Birth
Today’s Agenda
• Return & Discuss Tests
• Chicken Egg Lab
• Notes
– Obj. 1: Capacitation
– Obj. 2: Blocks to Polyspermy
– Obj. 3: Fertilization
• Fertilization WS
Obj. 1: Capacitation of Sperm
• Capacitation: the process by
which the acrosomal region of a
sperm becomes weakened
• This allows hydrolytic enzymes
to be released from the sperm
near the oocyte
Acrosomal reaction
Obj. 1: Capacitation of Sperm
Sperm are
incapable
of penetrating
an oocyte
unless
they are
capacitated
Obj. 2: Blocks to Polyspermy
Why would this be bad?
Polyspermy is prevented in humans
by:
– 1. Fast block to polyspermy
– 2. Slow block to polyspermy
Obj. 2 cont.
• 1. Fast block to polyspermy
–Depolarization of the
membrane
–Prevents other sperm from
fusing with oocyte membrane
Obj. 2 cont.
• 2. Slow block to polyspermy
–Releases cortical granules and
forms fertilization membrane
–Detaches all sperm in contact
with the oocyte membrane
Obj. 3: Fertilization
• Fertilization: fusion of the
sperm and egg nuclei
Obj. 3: Process of Fertilization
• 1. Sperm nucleus enters
oocyte
• 2. Secondary oocyte
completes meiosis II
• 3. Ovum & sperm nuclei
swell and become pronuclei
• 4. Pronuclei membranes
rupture, releasing
chromosomes
• 5. Chromosomes
replicate & undergo first
mitotic division
Fertilization Worksheet
Today’s Agenda
• Finish Fertilization WS
• Notes
– Obj. 4: Cleavage
– Obj. 5: Implantation
– Obj. 6: Gastrulation
• Play-doh activity
• Wrap-up
Obj. 4: Cleavage
• Cleavage: a period of rapid
mitotic divisions of the
zygote following fertilization
• Daughter cells increase in
number, but decrease in size
Obj. 4 Cont.
• Why is cleavage important?
–1. Enhances uptake of O2
and nutrients
–2. Provides a large number of
cells to serve as building
blocks
Zygote
4 cell stage
8 cell stage
Morula
• Blastula: hollow ball of spheres
–1. Trophoblast: help with
implantation and become
placenta
–2. Inner Cell Mass: becomes the
embryonic disk which the baby
will develop from
Obj. 5: Process of Implantation
• How does it work?
–The trophoblast adheres
to, digests, and implants
into the endometrial tissue
of the uterus
Transparency
Obj. 5 cont.
• Implantation begins about 67 days after fertilization
• Implantation is usually
completed by day 14
Obj. 6: Gastrulation
• Gastrulation: Cellular
rearrangements
that transform the
inner cell mass into
a three layered
embryo
Obj. 6 cont.
• The 3 germ layers are:
–1. Endoderm
–2. Mesoderm
–3. Ectoderm
Play-doh Activity
•Read Directions
•Make Play-Doh models
•Answer questions
Today’s Agenda
• Review WS
• Notes
–Obj. 7: Placentation &
Organogenesis
• Placental Coloring Activity
Matching Worksheet
Label Packet Diagrams
Can you put these in order?
• A.
• B.
• C.
• D.
• E.
• F.
4-Cell Stage
Zygote
Gastrula
Blastula
8-Cell Stage
Morula
Can you put these in order?
•
•
•
•
•
•
A.
B.
C.
D.
E.
F.
4-Cell Stage
Zygote
Gastrula
Blastula
8-Cell Stage
Morula
• ANSWER: B, A, E, F, D, C
What are the 3 germ layers?
• Endoderm
• Ectoderm
• Mesoderm
Label these on the drawing in your
packet:
• Endoderm
• Mesoderm
• Ectoderm
Obj. 7: Organogenesis
• Organogenesis: formation of
the body organs & organ
system
• All organs & tissues originate
from the 3 primary germ layers
Obj. 7: Placentation
• The Placenta: a temporary
organ that originates from
embryonic and maternal tissues
–It acts as the respiratory,
nutritive, and excretory organ of
the fetus
–It produces pregnancy hormones
–The mother and baby’s blood
never mix
4
7
5
8
6
9
Color your worksheet:
• Only color C, D, & H
• How does each structure
change between the first
picture and the last?
• Where would the mother’s
blood be? Draw an arrow on
your paper.
Today’s Agenda
• Quiz
• Fetal Development Intro.
–Obj. 8
• Group Activity
Obj. 8: Fetal development
• The baby is a fetus from week 9
to birth
• What happens?
–Further tissue and organ
specialization
–Growth and changes in body
proportions
Week 9
> 1” long
1 g: 0.03 oz
Week 40
~22” long
2.7 kg: 6-10 lbs
Today’s Agenda
• Maternal Changes
• Notes
–Obj 9-11
• Reading and discussion of
drug effects on a developing
baby
Maternal Changes:
• Anatomical
• Metabolic
• Physiological
Obj. 9: Maternal Changes
• Anatomical Changes
– Reproductive organs become
increasingly vascularized and filled
with blood
– The uterus and breasts enlarge
– The hormone relaxin loosens pelvic
ligaments and joints
Obj. 9: Maternal Changes
• Metabolic Changes
– Human Placental Lactogen: glucose
sparing for mother, promotes growth
of fetus, matures breasts for lactation
– Human Chorionic thyropin: increases
the rate of maternal metabolism
during pregnancy
Obj. 9: Maternal Changes
• Physiological Changes
–Nausea (morning sickness),
heartburn, constipation
–Increase in kidney function,
frequent urination
–Nasal stuffiness, dyspnea
–Blood volume and body water
increase, blood pressure
increases
Obj. 10: Parturition
• Parturition: the culmination
of gestation (birth)
• Labor: the series of events
that accompany birth
Overhead
Stages of Labor
• Stage 1: Dilation
– From onset of labor until cervix is
dilated to 10 cm
– Contractions become more vigorous
and frequent
– Infant’s head descends
– This is the longest stage (6-12 hrs.)
Stages of Labor
• Stage 2: Expulsion
– From full dilation to delivery of baby
– Contractions every 2-3 minutes,
lasting 1 min. each
– Normal length: 50 min (1st child), 20
min (2nd)
– Some mothers need a Cesarian
Section
Stages of Labor
• Stage 3: Placental Stage
–After baby is born, contraction
continue
–Placenta detaches from uterine
wall
–Placenta and umbilical cord are
examined for abnormalities
Obj. 11: The baby’s first breath
• Acidosis and the cold environment
excite respiratory control centers in
the brain
• Lungs are deflated and require
effort for first breath
• After first breath, lung surfactant
makes breathing easier
Other transitions:
• Umbilical cord and its vessels are
occluded
• Ductus venosus (the liver bypass in
a fetus) closes
• The foramen ovale closes in the
heart
Read about teratogenic effects
• What is a teratogen?
• When will it have the most
effect on the baby?
• Name 4 different teratogens
and their effects.