161 terms

NATS semester 2

Events during Prenatal Development
• Cleavage (cell division) in the Preembryonic
• Growth - in the Embryonic and Fetal phases -
increase in size and numbers of cells
• Morphogenesis - the embryo takes shape due
to the movement of cells (embryonic)
• Differentiation - cells show specialized
structure and function - become part of
specific tissues, organs and organ systems
Pre-embryonic development: Week 1
Human Blastocyst
3 Stages of Pregnancy
1. Pre-embryonic
2. Embryonic
3. Fetal
Week 2: Implantation
• At the end of week 1 - reaches uterus as a
• implantation of blastocyst marks beginning of
embryonic development
- trophoblast and inner cell mass (2 distinct tissues)
• "hatches" out of zona pellucida
• Inner Cell Mass
• Uterus is in its secretory phase
• Uterine glands complete growth and release a
secretion high in glycogen
• Spiral arteries form in the endometrium
• once in uterus - blastocyst attaches to endometrium
(usually back wall of uterus)
• endometrium attachment through trophoblast
• blastocyst completely embedded after 12 days
• contact with mother's blood vessels
• Trophoblast secretes human chorionic gonadotropin
zona pellucida
- prevents blastocyst from
implanting before it reaches uterus)
- until this time 32-64 cells have been the size of the original fertilized egg
- implantation week 2
Inner Cell Mass
- implantation week 2
- gives rise to embryo which later becomes a fetus
- starts out with 8 cells
- about 4 for body
- about 4 for extraembryonic tissues - the yolk sac
and the amnion
- gives rise to tissues for placenta
- secretes enzymes to digest part of endometrium
- secretes human chorionic gonadotropin
• Acts like LH
• marker of clinical pregnancy through blood test
• preserves corpus luteum which releases progesterone and keeps uterine lining intact
Secretary phase
- Luteal phase in ovary
- Progesterone is released by corpus luteum
- Endometrium is maintained by progesterone
Spiral arteries form in the endometrium
Uterine glands
endometrium attachment through trophoblast
- secretes enzymes that digest tissues
- blastocyst burrows into lining
Trophoblast secretes human chorionic gonadotropin
- Acts like lutenizing hormone during pregnancy
- Maintains corpus luteum (progesterone secretion) and
uterine lining
Early Embryo Embedded in Uterine lining
Week 2-3 pregnancy
• embryonic disk forms when inner cell mass
detaches from trophoblast
• yolk sac forms - first blood cells formed here
• amniotic cavity surrounds embryo
Gastrulation - primary germ layers (primitive
streak, which also establishes midline of body)
• ectoderm
• mesoderm
• endoderm
Trophoblast reinforced by mesoderm = chorion
Early Embryo Embedded in Uterine lining pt 2
Gastrulation - 3 primary germ layers
• ectoderm
• mesoderm
• endoderm
- gastrulation
- nervous system, skin, hair nails, inner ear, retina,
lens, mammary glands
- gastrulation
- connective tissue, muscles, blood, teeth,
cardiovascular system, urogenital system, skeleton
- gastrulation
- liver, pancreas, bladder, thyroid, tonsils,
parathyroid, bronchi and trachea of lungs
Gastrula - embryonic germ layers
Week 3 pregnancy
• less than 1/8 inches
• Formation of the nervous system
- Neural folds become the neural tube
• Development of heart begins (migration of
cells from both sides of the body)
- Cells beat before the heart is fully formed
Weeks 4 and 5 pregnancy
• Chorionic villi have developed and penetrate
uterine wall to interact with mother's circulatory
system (part will contribute to placenta)
• allantois (4th extraembryonic membrane) within
body stalk that connects embryo to chorion - will
form blood vessels of umbilical cord
• limb buds appear
• head enlarges with sense organs prominent
• tail
• especially sensitive to toxins
5 Weeks
Weeks 6 to 8 pregnancy
• 1.5 inches
• becomes recognizable as human being
• neck region develops
• reflex actions begin (ex. startle response)
Extraembryonic Membranes
• Sex-determining region on
the Y chromosome
• Gene for a protein that "turns
on" particular genes in other
chromosomes by bending
• Allows undifferentiated
gonads to become testes
• Begins functioning Week 6-8
SRY image
6-weeks - Indifferent Stage
-potential to develop as male or female
Development of the sex organs
• Sex of an individual is determined at conception (XX
is female and XY is male).
• If the SRY (the sex-determining region on the Y
chromosome) gene is present at week 6 then testis- determining factor is produced and the embryo
develops into a male.
• Anti-Mϋllerian hormone secreted by the testes
prevents the development of female sex organs.
• Dihydrotestosterone (DHT) produced by the
• If no SRY gene
- Wolffian ducts regress
- No DHT
- Mϋllerian ducts develop into a uterus and
uterine tubes
- Development of external organs
- Wolffian ducts stimulated to become male
genital ducts
SRY present - testis determining factor is
SRY absent - testis determining factor is
not generated
female reproductive system development in the womb
- first week after fertilization
- first stage of pregnancy
- second stage of pregnancy
- Week 2 to end of 2nd month
- third stage of pregnancy
- 3rd month to 9th month
- growth and maturation
3rd and 4th Months pregnancy
- Fetal Development Begins
• body increases in length
• fingernails, nipples, eyelashes, eyebrows, hair on
• cartilage is replaced by bone, and remains on
• external genitalia becomes visible (testes descend
in last trimester)
• physician can hear fetal heartbeat in 4th month
• fetus grows to 6 inches
5th to 7th months pregnancy
• increase in fetal movement that mother can feel
• head bent down in contact with knees (fetal
• skin is translucent and covered in lanugo (fine
down), coated with vernix caseosa (white
substance) to protect delicate skin from the
amniotic fluid
• fetus now 300mm (12 inches) and 1.38kg (3 lbs)
• possible for baby to survive outside the uterus at
end of this period
Vernix caseosa and lanugo on newborns
8th and 9th month pregnancy
fetus rotates so head is pointed to cervix
• fetus has grown to about 530mm (20.5 inches)
and 3.4kg (7.5lbs)
• subcutaneous fat has been deposited
the placenta
Placenta after Delivery
• Usually fully formed by end of embryonic
• Fetal portion - from chorionic tissue
• Maternal portion - from uterine tissue
• After 8th week chorionic villi begin to
disappear except at region of placenta
• Blood does not mingle
• Oxygen and nutrients diffuse across placenta• Umbilical cord - takes fetal blood to and from
• Placenta replaces lungs, digestive system and
• Placenta produces progesterone and estrogen,
which suppress ovulation (negative feedback
to the brain) and maintain the uterine lining
• Chemicals in mother's body can pass to fetus
through placenta
Fetal Circulation: Note that fetal and maternal blood do not mix (unless
there is trauma, like at birth).
Fetal Circulation: Note that fetal and maternal blood do not mix (unless
there is trauma, like at birth). pt 2
Fetal Circulation
• Rather than going to the lungs for exchange of
gases, the fetal blood goes to the placenta
• Placenta also provides nutrients (like digestive
system) and removes wastes (like kidneys)
• Adaptive structures in place during fetal
development will disappear after birth:
- Ductus venosus
- Foramen ovale
- Ductus arteriosus
Ductus venosus
connects the umbilical vein to the inferior vena cava, bypassing the liver
Foramen ovale
connects the two atria in the fetal heart
Ductus arteriosus
a blood vessel in a fetus that bypasses pulmonary circulation by connecting the pulmonary artery directly to the ascending aorta
Fetal Circulation pt 1
Fetal Circulation pt 2
Fetal Circulation pt 3
Fetal Circulation pt 4
Some Possible Signs of Pregnancy
• Missed period, spotting or
light period
• fatigue
• queasiness
• moodiness
• frequent urination
• tender swollen breasts
• "morning sickness" (can go
on all day)
Detecting Pregnancy
• Detect Human Chorionic Gonadotropin in mother's urine or
blood (produced by placenta within to maintain corpus
- Home pregnancy urine test after missed menstrual period
- Blood test at doctor's office (can detect low levels before first
missed period)
• Due date
- 280 days (40 weeks) after the first day of the last menstrual period
- Quick method - count 7 days from this day, and subtract 3 months
- 80% of births are within 10 days of this date.
Causes for Concern
• May indicate pregnancy loss or ectopic
• severe cramps
• dizziness
• low back pain
• severe abdominal pain
• prolongued bleeding
First Trimester - Weeks 1 to 13
• Symptoms may not be noticed until halfway
through this period
• Pre-embryonic, embryonic phases
• Gain of about 4 pounds
• Discomforts
- experienced to different degrees by different women
- fatigue, nausea, swollen breasts, frequent urination
- Caused by hormones
- Aggravated by stress, foods high in protein and fat, travel
Recommendations in first trimester
• Seek medical advice
• Family history taken
• Diet high in complex carbohydrates; eat several small
meals to control nausea
• Mild exercise and rest reduces fatigue
• Drink plenty of liquids, especially water, to avoid
• Take vitamin supplement with folic acid (important for
cell formation - lack can cause malformations of the
spine and brain - ex. spina bifida)
• Decide on birth method and location
• Prenatal testing throughout pregnancy
"Morning Sickness"
• Occurs in the first trimester, usually 2nd to 8th
• Affects about 75% of women
• Nausea and vomiting
• Aversion to certain foods, and strong-smelling
or strong-tasting foods
- Ex. Meats
- Ex. Coffee
- Ex. Broccoli, cauliflower, cabbage, Brussel sprouts
"Morning Sickness" as an Adaptation
• Work of evolutionary biologist Margie
Profet, early 90s
• Women with morning sickness have
lower rates of miscarriage
• Theory that morning sickness and
nausea protect the embryo
• Toxins are expelled by vomiting
• Food aversions prevent mother from eating
- "phyotestrogens" (estrogen-like molecules from
plants like clover, willow, alfalfa are noted to cause
miscarriage in some grazing animals; pine needle tea
was used by some First Nations as an abortifacient)
- Plant molecules that block progesterone synthesis
(ex. Fennel stalks or seeds - used in Ancient Greece)
- Plant molecules that discourage grazing and insects
- causes strong smell and taste
- Meats that may contain microbes
To Avoid
• Alcohol - affects development, increases risk of
• Smoking - causes slow fetal growth, low birth rate,
miscarriage, developmental problems
• Drugs
- review all medications with health provider
• Ex. Aspirin can cause fetal heart and lung damage by constricting
the ductus arteriosis
- Recreational drugs can cause addiction in the newborn,
and may increase risk of miscarriage or birth defects
- Caffeine - some research suggests increased risk of miscarriage when consumption is high
Second Trimester - Weeks 14-26
• Often experienced as the best time of pregnancy
• Begin to feel movements of fetus
• More energy
• Often morning sickness subsides, along with
aches and cramps
• Increased appetite
• Snoring (increased hormones cause nasal
passages to be swollen)
• Varicose or spider veins, skin discoloration,
stretch marks
• Thicker hair, faster growing fingernails
Facial pigmentation changes due to pregnancy (melasma)
• Caused by stimulation
of pigment-producing
cells (melanocytes)
• Due to female sex
hormone production
• Also found in premenopausal
and those on hormonal
birth control
• Disappears over months
after pregnancy
Recommendations in Second Trimester
• Increased calories by 300
• Ultrasound exams, fetal heartrate monitoring
• Gain about 1 pound a week
• Light exercise - low impact walking,
swimming, or continue pre-pregnancy
activities less strenuously
• Heartburn when lying down - allow time after
eating and avoid trigger foods
Third Trimester - Weeks 27-40
• Fetus grows rapidly (.5 lbs in weight gain each
week due to baby)
• Fetus moves into pelvic region - most in head- down position resting on pelvic bones
• Pelvic bones separate
• Mother can feel tired
• -dropping/lightening - baby moves closer to
cervix (heartburn subsides and breathing
becomes easier)
• -effacing/dilating - cervix things and opens
Symptoms in Third Trimester
• Water retention
- Lower blood circulation in legs
- Edema - tissues swell due to fluid retention
- Sleep on left side; raise feet while resting
• Preeclampsia
- Protein in urine
- High blood pressure causing blood vessels to constrict and
reducing blood flow to uterus and vital organs (often
damage to kidneys)
- Signaled by edema that comes on suddenly, appears
around face or eyes, or causes feet and hands to feel tight
- Treated with bed rest or premature delivery (esp. if beyond 37 weeks)
• Gestational Diabetes
- At 26-28 weeks blood glucose test
- Treated with diet or insulin
- Exact cause unknown
- May be due to insulin resistance due to pregnancy
• Braxton-Hicks contractions ("false labour")
- Irregular contractions
- Do not cause changes to cervix needed for birth
• Nesting
- Bursts of energy with a strong desire to clean, organize and
decorate the home
• Pressure on organs
Weight Gain in Pregnancy
• 25-35lbs for the whole pregnancy
• 7.5 is baby
• 7.5 stored nutrients
• 4 blood
• 4 other body fluids
• 2 breast enlargement
• 2 uterus enlargement
• 2 amniotic fluid
• 1.5 placenta
• Spontaneous end to pregnancy (natural loss) before
the embryo or fetus can survive independently
• 1 in 5 pregnancies
• Caused by:
- genetic abnormalities that compromise development
- teratogens (radiation, chemicals, smoking, drinking and
- certain medications
- infections
• Chemical pregnancy - hCG levels rise (produced and
detected) then drop, leading to miscarriage - an egg
was fertilized then stopped developing before
• A miscarriage after the 20th week
• Less than 1% of all births
• Indicated by decreased fetal movement
• Persistent cramping or stabbing pain in lower
back, pelvis or abdomen
• Vaginal bleeding
• Wait 3 months before conceiving again
• Investigate factors
• Receive grief and psychological support
The Placenta and Risk of Birth Defects
• Potential for drugs and toxins to cross the
placenta and enter the embryo and fetus
• Environmental pollutants - ex. dioxin
• Teratogens - substances that cause
abnormalities in the embryo or fetus
If you think you may be pregnant or wish to be
• Consult with a doctor regarding medications
• Avoid all alcohol and recreational drugs
Placenta diagram
Thalidomide, 1950s
• Used as an anti-nauseant during pregnancy
• Children born with limb abnormalities, damaged
hearts and digestive tracts
• Drug company initially denied link
• Banned, then led to government policies on regulations of drugs
Fetal Alcohol Spectrum disorder
• Alcohol crosses the placenta
• Can increase risk of miscarriage
• Development can be impacted, and may result in:
- low birthweight
- features of the head and face
- intellectual disabilities
- Delayed growth
- Problems with hearing or vision
- Problems with bones, joints, muscles, kidneys, heart, genitals
- Behavioural problems
Smoking, Drugs
• mother's consumption affects fetus
• drug use can change blood pressure which
affects blood to fetus's brain - many other
health problems
• smoking results in ingesting toxins that reach
the fetus - poor health, respiratory diseases,
increased chance of cleft lip and palate
Prenatal Testing
• Helps parents know what to expect
• Helps plan for appropriate delivery method,
and any needed care
Methods of Prenatal Testing
• Ultrasound
• Nuchal translucency screening
• Chorionic Villus Sampling (CVS)
• Amniocentisis
• Cordocentesis
• Cell-Free Fetal DNA (cffDNA)
• Karyotyping and Genetic Testing
Methods of Prenatal Testing picture
Nuchal Translucency Screening
• At 11-13 weeks
• Ultrasound images used to measure spaces at
back of neck
• Fetuses with Down Syndrome accumulate
more fluid in this area
• Not a conclusive test
• Chromosomal analysis needed for diagnosis
2 Kinds of DNA Testing
• Karyotyping
- Looking for abnormalities in chromosome number
or shape
• Genetic testing
- Looking for abnormalities in the genetic sequence
of disease-causing genes (inherited diseases)
Chromosomal Abnormalities - Some
caused by "nondisjunction" during meiosis
Chromosome Abnormalities
Chromosome Abnormalities Turner
X monosomy (Turner Syndrome)
• Infertility
• Short stature (missing one copy
of gene for bone growth on X
• Neck webbing and swelling of
legs and feet due to lymphatic
• Some cardiovascular problems
• Can be treated with estrogen
replacement therapy
Pre-implantation genetic diagnosis
• Oocytes are harvested
from the ovary
• In vitro fertilization is
• Mother's DNA can be
investigated from the
polar body
• At the cleavage or
blastocyst stage, a hole
can be made in the
zona pellucida, for cell
• DNA is analyzed
Chorionic Villus Sampling
• Recommended in the first trimester (10-13 weeks)
• Sample of the chorionic villi is taken
• Guided by ultrasound
• Local anaesthesia may be used
• Fetal blood and tissue - cells and DNA
• Invasive and - slight increase risk of miscarriage
• After 15 weeks
• No anaesthesia needed
• Sample of the amniotic fluid (15-25cc) is withdrawn
• Fetal cells (usually skin and bladder) are present in the fluid
• Cells can be examined for chromosome analysis
• Fluid can also be examined for enzymes
• Results take 1-3 weeks
• After 18 weeks
• Also called "Percutaneous umbilical blood sampling"
• Guided by ultrasound
• Fetal blood sample normally taken from umbilical vein
(puncture of an artery has a higher risk due to possible
constriction of the artery)
• Detects chromosomal abnormalities
• Higher risk method reserved for higher risk pregnancies
- Risk of pregnancy loss = 1.3% for fetuses with no anomalies;
1.3% to 25% for fetuses with anomalies, or fetal growth
restriction (low weight for gestational age)
Cordocentesis, cont'd
Cell-free fetal DNA (cffDNA)
• DNA fragments from broken-down trophoblast
cells are capable of moving across fetal-maternal
• Found in maternal blood serum
• A less invasive approach
• Currently used for screening, and may be
followed by another more invasive traditional
method (the others listed above)
• Being developed for fetal diagnosis
Cell-free Fetal DNA, cont'd
Uterine contractions and labour
• Labour initiated through hormones released in
placenta and fetus
• Contractions occur throughout pregnancy
• Stronger and more frequent towards the end of
• Braxton Hicks contractions = "false labour"
• True labour = uterine contractions that occur
every 15‐20 minutes and last for at least 40
seconds each.
• Labour ‐ process of delivering child and placenta
Posterior pituitary gland
stores and releases oxytocin
Stage 1 - Cervix dilates and effaces
• Expulsion of mucus plug in cervix
• Uterine contractions as cause
• Disappearance of cervical canal
• Lower cervix pulls up toward head (called
"effacement") to become part of the lower
uterine wall
• Baby's head acts as a wedge in this process
• Rupture of amniotic membrane "breaking the
Stage 1‐ Cervix Effaces and Dilates
Stage 2 - Delivery of Infant
• Begins with a fully dilated uterus and ends
with birth
• Uterine contractions 1‐2 minutes, lasting 1
• Desire to push down that increases as head
descends into vagina
• Baby's head turns towards back
• An episiotomy (incision) may be performed
between the vagina and rectum to enlargen
the opening
• Head is delivered first in normal delivery
• Shoulders emerge one at a time
• Rest of baby delivered quickly following
• Umbilical cord clamped and cut
Stage 2 birth
Stage 3 birth
• Placenta is delivered
• Occurs about 15 minutes after baby
• Dislodged by shrinking of uterus
Natural Childbirth
• Choosing to give birth with little or no pain
• Lamaze, yoga, hypnosis and other techniques
that aim to eliminate tension and anxiety
during labour and birth
• Imagery, visualization, focusing, touch and
breathing are used to distract from pain (like
meditations we do in class)
• Birthing partner can reduce pain and anxiety
Lamaze method
• Painless childbirth, or "psychoprophylaxis"
• Pioneered by French physician Dr. Fernand Lamaze (1891-1957) in the 1950's
• Breathing, relaxation, focusing away from the pain
• Education for both parents
• Birth partner learns to support the birth mother
LeBoyer Method
• Pioneered by French obstetrician Dr. Frédérick Leboyer (1918-2017)
• Eases transition for newborn
- Darkened, warm and quiet delivery room
- infant placed on mother's abdomen
- umbilical cord not cut until it stops pulsating
- Infant immersed in warm water after birth (mimics amnionic fluid)
Pain Management birth
• Analgesics
- pain relief without loss of feeling or muscle movement
• Anaesthetic
- blocks all feeling
• Epidurals
- continuous IV drip of analgesics into area near spinal cord
- may have some ability to push
• Spinal blocks
- anaesthetic injected into spinal cord
• Systemic pain medication
epidural an
Possible Artificial Induction of
• 2 weeks after due date
• Certain medical conditions in mother
• Baby is too large and C‐section may be needed if later
• Water breaks without contractions (increases risk of infection)
• Living far from a birthing location
• Placenta stops functioning
• Medications administered vaginally to dilate and efface
• Pitocin - synthetic oxytocin
• Monitor baby's health
Cesarian section (C‐section)
• Planned or emergency surgical procedure,
whereby incision is made through abdomen,
uterus and amniotic sac
• General or local anaesthesia
• Fetus, placenta and umbilical cord lifted out
• cervix not dilating
• baby's heart rate is too slow or fast
• prolapsed umbilical cord (comes through cervix before baby, cutting off oxygen supply)
• placental abruption - placenta separates from the uterine wall too soon, cutting off oxygen supply
• outbreak of genital herpes (helps avoid infecting fetus)
• multiple births
• small pelvis/large baby
• placenta previa - placenta is low and blocks cervix
• preeclampsia - high blood pressure associated with pregnancy
• breech or transverse position of fetus
• known abnormality or illness of fetus
placenta blocking cervix
- sudden weight gain
- edema
- high blood pressure
• ducts end at nipple, and are divided in
breast to 15‐25 different lobules containing
• breasts enlarge, ducts and alveoli increase
• prolactin initiates milk production (anterior
• oxytocin causes lobules to contract
(posterior pituitary)
• colostrum comes first - protein‐rich thin
yellow fluid
• milk production continues if child is
suckling - nerve endings in nipple stimulate
hypothalamus which activates pituitary
lactation diagram
The hypothalamus produces oxytocin
which is stored in the posterior
pituitary and released into the blood.
Oxytocin causes contraction of the
myoepithelial cells in the milk ducts,
causing milk ejection
Immediately after birth - the neonate (newborn)
• Umbilical cord is cut
• Mucus is removed from the airway with suction
• Vitamin K shot (to prevent rare bleeding disease)
• Examined for any visible problems
• Eye ointment to protect from infection
• Cleaned, dried and rubbed with a soft towel
• Weight, length, head circumference, heart rate,
temperature recorded
• Developed by Dr. Virginia Apgar in 1952
• Calculated in the first minutes immediately after
birth, to establish newborn health, or to indicate need to monitor if initial score is low
• Enables early treatment, if needed
• Appearance, Pulse, Grimace, Activity, Respiration
APGAR scale
A = Appearance
ex. Cyanosis
• A bluish appearance all over, or at the
• "blue baby syndrome"
• Caused by low blood oxygen
Possible Health issues associated with cyanosis
• Respiration:
- If premature, it could be that not enough surfactant covers the air sacs of the lungs - respiratory distress
syndrome ( treatment is to stimulate adrenal glands
to secrete more cortisol)
• Circulation
- The ductus arteriosis, ductus venosus and foramen ovale normally close due to changes in blood pressure after birth. If not, the lungs may not receive sufficient blood. Drug treatment or surgery may be needed.
• Birth to 1 year
• Maturation of nervous and muscular system
allows for motor skills development and
connections between neurons in the brain
• Interrelationship between systems - feedback
to nervous system from muscles, skin, joints,
eyes, ears etc.
Growth Charts
• Set by the World Health Organization (WHO)
based on data collected from a large number of
• Allow for monitoring of a child's growth process
• Head circumference, height, weight, by gender
• Tracks progress and presents expected growth
curve for the future
• Helps identify possible health issues
• Genetic conditions like Turner's or Down
Syndrome have distinct growth curves (slower
physical growth)
Tracking Weight using a Growth Chart
Piaget's 4 Developmental Stages
• A pioneer of the science of determining
stages of childhood development (children
are not small adults!)
• Other systems have developed since
• Piaget's 4 developmental stages ‐
- Sensorimotor (0‐2) - object permanence
- Preoperational (2‐7) - pretend play,
- Concrete operational (7‐11) ‐ conservation
- Formal operational (12+) ‐ reasoning
• Expectation of physical and cognitive abilities
at particular ages
• Helps track health and manage expectations
• Recommendations for parents and caregivers
can be offered to help encourage and
reinforce these developments
• Girls: begins between 10 and 14
• Boys: begins between ages 12 and 16
• Secondary sex characteristics appear
• Social and psychological changes
Secondary Sex Characteristics - Development at Puberty
• hypothalamus becomes less sensitive to feedback control from the sex hormones
As a result....
• GnRH production increases in hypothalamus
• GnRH stimulates anterior pituitary
• pituitary releases FSH and LH testes or ovaries
produce more hormone (ex. Testosterone, estrogen)
• when adult levels of gonadal hormone reached,
hypothalamus increases sensitivity to feedback
Hypothalamic‐Pituitary‐Gonadal Axis
• An "androgen", or "anabolic steroid"
• In men, produced in the testes, with some
production in the adrenal glands
• In women, smaller amounts are produced in
the ovaries, and adrenals
• LH (also called ICSH = interstitial cell
stimulating hormone) promotes androgen
production in the interstitial cells
• Puberty
- begins when the hypothalamus becomes less
sensitive to negative feedback control of
- Hypothalamus produces more GnRH
- LH and FSH production increased
• LH promotes androgen production in the
interstitial cells
• Maturation and function of penis and testes
• Secondary sex characteristics
Cross section of seminiferous tubule
Leydig cells, also called Interstitial Cells, are found in the space between seminiferous tubules and
produce testosterone
Seminiferous tubules before and after puberty
Primary and Secondary Sex characteristics: testosterone
• Primary sex characteristics ‐ maturation and
function of penis and testes
• Secondary sex characteristics
- Bodily characteristics other than reproductive system
- Appear during puberty
- Facial and body hair
- Muscle growth
- Thickened skin
- Bone structural changes
- Increased activity in oil and sweat glands (can cause
- Enlargement of larynx and vocal cords
• Oogenesis
• Growth and activity of mammary glands
• Growth of uterus and vagina
• Regulate LH and FSH through feedback control
• Skeletal maturation and bone mineralization
Secondary Sex Characteristics: estrogen
• Secondary sex characteristics in females
beginning in puberty
- Body hair
- Fat distribution (more extensive than males)
- Enlargement of the pelvic girdle
- Breast development
• Bone growth in puberty (males have estrogen
• Breast development
• Prepare uterus for implantation of fertilized egg
• Maintain uterus in pregnancy
• Stimulate growth of mammary glands
• Regulate secretion of LH and FSH
• Large increase in pregnancy
Tanner Scale
Biological, Psychological and Social Dimensions of Gender
Androgen Insensitivity Syndrome
• Can be part of a gender identity spectrum and is an intersex condition, with which a person may identify
• Genetically male (XY)
• Cells cannot respond to androgens to some degree
• May have feminine body features
• No uterus, cervix or fallopian tubes
• Testes may remain undescended (internal testes)
Trans Brains
• Most commonly contracted sexually transmitted
• There may not be symptoms of infection
• Caused by a bacterium Chlamydia trachomatis
that reproduces inside the cells that line the
reproductive tract in men and women
• Uses the cell's machinery for its functions
• 2 forms in life cycle:
- Elementary Body is infectious form
- Reticulate Body is form that replicates itself
• Elementary Body (EB) establishes contact with the "host" cell
• Causes the cell to envelope it creates an ideal environment for reproduction inside cell
• Converts to Reticulate Body (RB)
• RB divides every 2-3 hours for 7-21 days
• RB converts to infectious EB form
• EB released from cell to infect more cells
Chlamydia - Symptoms
• Mild or no symptoms (75% of women and
50% of men have no symptoms)
• Infects reproductive tract, urinary tract and
eyes (can cause blindness)
• Mild burning on urination and some discharge
in men - can infect prostate and epididymis
• Vaginal discharge and urinary tract sensations
in women
• Can cause pelvic inflammatory disease,
blockage of uterine tubes, ectopic pregnancy
• Can result in infertility
• Increases probability of HIV infection
• Inflammation of eyes if newborns in contact
with infection during birth
• Treated with antibiotics
Gonorrhea - Neisseria gonorrhoea
• A bacterium - diplococcus (2 spherical cells together)
• Carried in vaginal fluid and semen
• One of the most common STIs - infection growing
• May be accompanied by chlamydia infection
Gonorrhea - Symptoms
• May have no symptoms
• Men - greenish-yellow discharge from urethra,
and pain during urination
• Women - can cause Pelvic Inflammatory Disease - abdominal pain
• Can cause scarring of uterine tubes, infertility,
ectopic pregnancy, premature birth, eye infection
in newborns
• Can spread to other areas - anal pain and pus,
mouth and throat infection, eye infection, heart
damage and arthritis
Gonorrhea - treatment
• Single exposure to infected partner - 50-60%
transmission risk in women, 20% in men
• Diagnosed by microscope, or growing culture
• Treated with antibiotics
• Evidence of antibiotic resistance - classified as
Syphilis - Treponema pallidum
• Spirochete
• Creates a "chancre" (sore with hard edges) in
primary stage
• transferred through contact with sore - on
genitals and other regions
Syphilis - Symptoms
• Primary stage - Chancre at point of infection - usually heals on its own
• Secondary Stage - Rash once spread through
• Tertiary Stage
- affects cardiovascular system, weakens arteries
- may affect nervous system (mental impairment,
psychological disturbance, blindness, shuffling walk)
- May develop "gummas" - ulcers on skin and internal organs
• Can cause fetus to be stillborn, blind, or have
other anatomical problems
Syphilis - Treatment
• Blood test (antibody) and microscope
diagnosis (fluid from lesions)
• Penicillin treatment
Virus Life Cycle
Herpes Simplex (HSV)
• Invades epithelial cells - cells lining mouth and
genitals, skin
• HSV-1 - mostly cold sores and fever blisters
• HSV-2 - mostly genital herpes
• May have no symptoms
• May have tingling/itching
• Appearance of blisters on genitals
• Blisters rupture and leave painful ulcers that heal
in 5 days-3weeks
• May accompany fever, pain on urination, swollen
lymph nodes in the groin, or discharge in women
• Can cross the placenta and infect a fetus,
which may cause blindness or
brain/neurological damage
• Can be spread even if no lesions are visible
• Can be spread to other parts of body (eyes)
HPV-11 and genital warts
• Over 6 million infected each year
• Many do not seek medical attention
• May or may not be visible lesion
• Lesions found on penis and around vaginal
• Newborn can become infected during birth
Human Papilloma Virus
• Over 100 kinds of HPV - Type 11 causes
genital warts
• Infects damaged epithelial tissue
• Associated with cervical cancer
• Associated with tumors of the vulva, vagina,
anus and penis, and the mouth
Warts - Prevention/Treatment
• No cure
• Treatment includes surgery, freezing, acid,
laser burning
• Can be transferred even after treatment
• Prevention - abstinence, monogamy with
uninfected partner
HPV vaccine
• Gardasil
• Improves immune response to virus
• Vaccine is most effective if administered
before sexual activity begins
• Protects nearly 100% against HPV forms that
cause cervical cancer and genital warts
• Regular Pap tests still needed for girls
• Transmitted through
- Sexual contact
- Needle sharing
- Blood transfusion (now screened)
• Infect helper T lymphocytes (white blood cells)
called CD4 cells (immune function)
• No symptoms at first, later loss of weight and
diarrhea and infections like thrush and herpes
• Final phase - AIDS = Acquired Immune
Deficiency Syndrome - opportunistic infections
due to diminished CD4 count
HIV Drug treatments
• No cure
• No vaccine, but some trials
• reverse transcriptase inhibitor - inhibits copying of genetic viral information
• protease inhibitors affect assembly of viral particles
• Highly active antiretroviral therapy (HAART) can
cause HIV to be undetectable, but must be continued
• side effects are from non-specificity of the drugs
Preventing STI
• Abstinence is the only 100% guarantee of
• Sex with multiple partners increases risk
• Discuss sexual history with partners
• Use a latex condom and practice good hygiene
• Get tested, particularly where there are visible
lesions, pain on urination, itching, discharge
3 Stages of the Prenatal Period
1. Pre‐embryonic
- first week after fertilization
2. Embryonic
- Week 2 to end of 2nd month
3. Fetal
- 3rd month to 9th month
- growth and maturation
Pre‐embryonic Period
• Week 1
• Ovulation, and fertilization in the uterine
• Zygote (fertilized egg) travels to the uterus
• Cleavage (cell division without change in size)
• Formation of the morula (ball of cells)
• Formation of the blastocyst (inner cell mass
and trophoblast cells)
• After ovulation the egg lasts 6‐24 hours
• After ejaculation sperm last 24‐48 hours
• Fertilization takes place in the uterine tube
• Egg cell moves through uterine tube after
ovulation (contractions and ciliated cells)
• Spermatozoa mature as they pass through
epididymis (10‐14 days)
- Motility (movement forward)
- Binding proteins for zona pellucida
• at ovulation cervical secretions are watery and
less acidic (more favourable for moving
• cervical crypts are reservoirs for escaping
• 1% or less of sperm move to uterus
• only 20‐30 out of 150‐200 million reach egg
• A single sperm cell fertilizes the egg
• Sperm head binds zona pellucida
- species‐specific receptors (ex. A mouse sperm
would not bind to the zona pellucida of a human's
• Acrosome of sperm releases digestive
enzymes which break down zona pellucida
• Sperm passes through zona pellucida
• Sperm binds to egg membrane
• Only one sperm enters egg
• Chemical changes to plasma membrane and
zona pellucida prevent other sperm from
- Egg cell membrane changes properties
- Cortical granules release enzymes
- Zona pellucida becomes a fertilization membrane
preventing other sperm from fertilizing.
• Plasma membranes fuse
• meiosis II is resumed in the secondary oocyte,
producing a polar body and a pronucleus with a
haploid number of chromosomes
• Sperm cell contents enter egg
• Sperm pronucleus and egg pronucleus fuse and
are surrounded by a nuclear membrane
• Granules release enzymes that convert the zona
into a fertilization membrane
- harden the zona
- prevent other sperm from binding
fertilization image
Cleavage, Morula and Blastocyst
• fertilized egg is a zygote
• division while moving down the uterine tube
• morula is ball of cells
• blastocyst is first cell differentiation
- inner cell mass - becomes the embryo
- trophoblast - becomes the chorion (fetal
• Blastocyst "hatches" out of zona pellucida
Week 2: Implantation
• At the end of week 1 - reaches uterus as a
• implantation of blastocyst marks beginning of
embryonic development
- trophoblast and inner cell mass (2 distinct tissues)
• "hatches" out of zona pellucida
- zona pellucida prevents blastocyst from
implanting before it reaches uterus)
- until this time 32‐64 cells have been in zona
pellucida, the size of the original fertilized egg
• Inner Cell Mass
- gives rise to embryo which later becomes a fetus
- starts out with 8 cells
- about 4 for body
- about 4 for extraembryonic tissues - the yolk sac
and the amnion
• Trophoblast
- gives rise to tissues for placenta
- secretes enzymes to digest part of endometrium
- secretes human chorionic gonadotropin
• Acts like LH
• marker of clinical pregnancy through blood test
• preserves corpus luteum which releases progesterone
and keeps uterine lining intact
• Uterus is in its secretory phase
- Luteal phase in ovary
- Progesterone is released by corpus luteum
- Endometrium is maintained by progesterone
• Uterine glands complete growth and release a
secretion high in glycogen
• Spiral arteries form in the endometrium
• once in uterus - blastocyst attaches to endometrium
(usually back wall of uterus)
• endometrium attachment through trophoblast
- secretes enzymes that digest tissues
- blastocyst burrows into lining
• blastocyst completely embedded after 12 days
• contact with mother's blood vessels
• Trophoblast secretes human chorionic gonadotropin
- Acts like lutenizing hormone during pregnancy
- Maintains corpus luteum (progesterone secretion) and
uterine lining
normal and ectopic pregnancy
epithelium tissue
covers the body surface and lines its cavities, STDs and bacteria like to live here