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Development: Regardless of
where the development takes place,
the developing embryo has certain
needs that must be met for survival
•nourishment
•proper temp
•oxygen
•protection
•means of getting rid of wastes
Pregnancy and Early
Development
Pregnancy, or gestation
– Is the carrying of developing young within the
female reproductive tract
– Is measured as 40 weeks from the start of the
last menstrual cycle in humans
• Gestation is pregnancy
– It begins at conception and continues until birth
– Human gestation is 9 months
– Mouse gestation is 1 month
– Elephant gestation is 22 months
• Structures develop that assist the developing
embryo
– The amnion, a fluid filled sac that encloses and
protects the embryo
– The yolk sac, which produces the embryo’s first
blood and germ cells
– The allantois, which forms part of the umbilical
cord
– The chorion, which becomes part of the
placenta
The Placenta
oxygenated blood from mother’s artery
deoxygenated blood to mother’s vein
villus
umbilical vein
umbilical artery
• The placenta allows for a variety of
substances to pass from mother to fetus
– Nutrients
– Waste
– Gas (oxygen & carbon dioxide)
– Protective antibodies
– German measles virus
– HIV
– Drugs (prescription and nonprescription)
– Alcohol
– Chemicals in tobacco smoke
Prenatal Development
• When the fertilized egg arrives in the uterus, it
implants itself in the thickened, spongy uterine wall.
• The gastrula forms, differentiation of cells and growth
occurs.
• The developing embryonic membranes become part
of the placenta and umbilical cord.
• After eight weeks of development the embryo is called
the fetus.
• The period of time between the fertilization of the egg
and the birth of the offspring is called gestation
– In humans the gestation period is nine months or
approximately 266 days.
Prenatal Development
• During this time, it is essential that the
expectant mother provide good prenatal care by
eating nutritious foods, avoiding alcohol,
tobacco, and drugs, and receiving proper
medical attention regularly.
• Using tobacco, alcohol
and drugs may cause
low birth rates,
premature births,
Fetal Alcohol Syndrome
as well as other
birth defects.
http://www.youtube.com/watch?v=OsXK8Y4-PAs
Over the counter drugs and pregnancy (3min)
http://www.ksl.com/?nid=148&sid=14491332
Drug dependent babies (5min)
http://rockcenter.nbcnews.com/_news/2012/07/05/12570381-prescription-drugaddiction-among-pregnant-women-becoming-monstrous-tidal-wave?lite
Prescription drugs and pregnancy (12minutes)
The Stages of Pregnancy
• Pregnancy is divided into three trimesters
The First Trimester
• A human embryo @ about 6 weeks
• A human embryo @ about 8 weeks
A human fetus @ about 10 weeks
• By the end of the first trimester (12 weeks)
– The fetus looks like a miniature human being
– The sex of the fetus can be determined by
ultrasound
A human fetus @ about 12 weeks
The Second Trimester
• The main developmental changes during the
second and third trimesters involve an
increase in size and general refinement of
the human features
• A fetus at 14
weeks, 2 weeks
into the second
trimester
• At 20 weeks, the fetus
– Is about 19
cm (7.6 in.)
long and
weighs about
half a
kilogram (1 lb)
– Has the face
of an infant
The Third Trimester
– Is a time of rapid growth
– Includes many important physical changes
At birth
– A typical baby is about 50 cm (20 in.)
long and weighs 2.7–4.5 kg (6–10 lb)
6 lbs. 13.5 oz
8 lbs. 3 oz
The Human Zygote
Fertilization
16 Cells
Two Cells
Morula Stage
Four Cells
Blastocyst Stage
Implantation
Human Gestation
3 Weeks
Human Gestation
3 Months
Summary of Human Development
Childbirth
• The birth of a child is brought about by a
series of strong, rhythmic contractions of the
uterus called labor
• Hormones play a key role in inducing labor
• There are three
stages of labor
• Dilation of the cervix
is the first stage
– Cervix reaches full
dilation at 10cm
– Longest stage of
labor (6-12 hours or
longer)
• Expulsion is the second stage
– Period from full dilation
of the cervix to delivery
of the infant
– Uterine contractions
occur every 2-3
minutes
– Mother feels urge to
push down with her
abdominal muscles
– Infant is forced down
and out of uterus and
vagina
• The delivery of
the placenta is
the final stage of
labor
– Usually occurs within
15 minutes after the
birth of the baby
• Hormones continue to be important after the
baby and placenta are delivered
– Decreasing progesterone and estrogen levels
allow the uterus to return to its pre-pregnancy
state
– Oxytocin and prolactin stimulate milk secretion
http://www.doctoroz.com/videos/normal-labor-and-birthanimation normal labor and delivery
Moving babies
http://www.youtube.com/watch?v=w7qVJiYBlbo
http://www.youtube.com/watch?v=JKlPGzrrQZA&feature=
related
Postnatal Development
• Following birth, the
placenta is discarded
from the mother’s body
and the mother begins
producing milk from
mammary glands
located in the breasts.
• The mother’s breast
milk is normally the
best natural food for
a newborn baby.
Applications of reproductive technology:
Reproductive technology has medical,
agricultural, and ecological applications.
This technology has also stirred ethical
concerns as well, especially where this
technology applies to humans
1. Genetic engineering in the field of agriculture
• Crops resistant to insects, weed killer, frost
2. Cloning- used to make large numbers of
identical copies of desired organisms
3. Artificial insemination. Can freeze sperm
or embryos and use them at different
locations or at different times
• Scientist are also using these
technologies to help engendered
species
4. The use of reproductive hormones to control
and combat pest populations of insects without
using poisonous chemicals
5. Human reproductive problems:
• Hormonal therapy
• IVF (In-vitro fertilization)
REPRODUCTIVE HEALTH
• issues of human reproductive health
– Contraception
– Transmission of disease
– Infertility
Contraception : Is the deliberate prevention of
pregnancy
• prevents pregnancy in one of three ways
– Blocking the
release of
gametes
– Preventing
fertilization
– Preventing
implantation
Surgical Methods
Vasectomy
Cutting and tying
of sperm ducts
Tubal ligation
Cutting and tying
of oviducts
Birth Control
• Hormonal contraceptives
(the
pill, the patch, and the vaginal ring)
– These hormones work to inhibit the body's natural
cyclical hormones to prevent pregnancy. Pregnancy
is prevented by a combination of factors. The
hormonal contraceptive usually stops the body from
ovulating.
– No ovulation = no egg = no fertilization = no baby!
– No hormones taken for 7 days = menstruation
Barrier Method
Male and female condoms prevent sperm from
entering the vagina
Diaphragm fitted over the cervix & along with use of
spermacide to kill sperm
No sperms= no fertilization= no baby!
Sexually Transmitted Diseases
• Sexually transmitted diseases (STDs)
– Are contagious diseases spread by sexual
contact
• Viral STDs, such as AIDS, genital herpes, and
genital warts, cannot be cured but can be
controlled by medications
Human Reproductive Disorders
• Sexually transmitted diseases may be transmitted by
both males and females and may cause sterility or
death if not treated by a competent physician.
• Some sexually transmitted diseases in humans are
syphilis, gonorrhea, genital herpes, and AIDS.
REPRODUCTIVE TECHNOLOGIES
• Reproductive technologies
– Can help solve problems related to the inability
to conceive a child
• Infertility
– Is the inability to have children after one year of
trying
– Problems in the man, such as underproduction
of sperm or impotence
• Female infertility can result from a lack of
eggs or a failure to ovulate
• There are technologies available to help
treat the many forms of infertility
In Vitro Fertilization (IVF)
– Happens under artificial, laboratory conditions
-Begins with the surgical removal of eggs
and the collection of sperm
- Involves fertilization of eggs in a petri dish
• IVF
– Offers choices that nature does not
– Raises many moral and legal issues
http://www.sumanasinc.com/webcontent/animations/content/invitrofe
rtilization.html
IVF
• Show reproductive technologies ppt
Basic Concepts of Embryonic
Development
• The key to development in all organisms is
that each stage of development takes place
in a highly organized fashion
• About one week after conception
– The embryo, which has become a blastocyst,
implants itself in the uterine wall
– The outer cell layer, the trophoblast, becomes
part of the placenta
Gastrulation produces a three-layered
embryo
• Gastrulation is the second major phase of
embryonic development
– It adds more cells to the embryo
– It sorts all cells into three distinct cell layers
– The embryo is transformed from the blastula into
the gastrula
• The three layers produced in gastrulation
– Ectoderm, the outer layer
– Endoderm, an embryonic digestive tract
– Mesoderm, which partly fills the space between
the ectoderm and endoderm
Organs start to form after gastrulation
• Embryonic tissue layers begin to
differentiate into specific tissues and organ
systems
• In chordates
– the notochord develops from the mesoderm
– the neural tube develops from the ectoderm
• The neural tube becomes the brain and
spinal cord
Changes in cell shape, cell migration, and
programmed cell death give form to
the developing animal
• Tissues and
organs take
shape in a
developing
embryo as a
result of
– cell shape
changes
– cell migration
Embryonic induction initiates organ
formation
• Induction is the mechanism by which one
group of cells influences the development of
tissues and organs from ectoderm,
endoderm, and mesoderm
– Adjacent cells and cell layers use chemical
signals to influence differentiation
– Chemical signals turn on a set of genes whose
expression makes the receiving cells
differentiate into a specific tissue
http://player.discoveryeducation.com/?guidAssetId=B76C7495-F4F0-4CB4926E-BFD46A3060A8
Identical Twins “nature vs nuture”
The amazing conception happened after two eggs were fertilized at the same
time in the womb. Both Kylie and her partner Remi Horder, 17, are of mixed
race. Their mothers are both white and their fathers are black. According to the
Multiple Births Foundation, baby Kian must have inherited the black genes from
both sides of the family, whilst Remee inherited the white ones.
A mixed-race British mom, Kylie Hodgson, gave birth in 2005 to twins, one of
each — one black, the other white. The odds of such a birth are about a
million to one, experts said. Although occurrences of this nature sometimes
occur when a woman conceives twins fathered by two different men, this was
a much rarer case in which a single pairing produced twins with distinctly
different physical attributes (e.g., skin tone, hair color, eye color) rather than a
blending of their parents' characteristics. The parents, Kylie and her partner,
Remi Horder, are of mixed race themselves, both having been born to white
mothers and black fathers. Their twin girls — Kian and Remee — were both
born with blue eyes, with Remee having blonde hair and Kian having black
hair and somewhat darker skin than her sister. Since then, Remee's skin tone
has become lighter, while Kian's has become darker and her eyes have
turned brown.
In the womb
http://channel.nationalgeographic.com/channel/in-the-womb/videos/in-the-womb/
Life’s Greatest Miracle
http://www.pbs.org/wgbh/nova/body/life-greatest-miracle.html