Birth Control and STIs, Assisted Reproduction, Fertilization to Implantation, Fetal Development

Birth Control Pill

Birth Control Pill

• 8% Failure Rate

• Synthetic estrogen and progesterone

  • Inhibits GnRH

  • Inhibits FSH and LH

  • Inhibits follicular growth and ovulation)

• Must take at the same time every day to maintain high levels of hormones

The Patch

• 8% Failure Rate

• A patch the delivers synthetic estrogen and progesterone

Nurvaring

• 8% Failure Rate

• Silicone ring worn inside vagina

• Secretes hormones

• Can take it out for up to 1 hour without losing effectiveness

Depo Provera (Shot)

• 3% Failure Rate

• A shot of progesterone every 3 months

• Side effects: Nausea

Emergency Contraception Pill (Plan B)

• Can be taken up to 5 fays after exposure to sperm

• High dose of estrogen and progesterone to prevent ovulation

• 75% effective and more effective the sooner it is taken

• Doesn’t remove implanted embryo from uterus (not abortion pill)

Lactational Amenorrhea

• Breastfeeding to prevent ovulation

• Does not work

Vasectomy

• Vas deferens is cut, sutured, cauterized, or clamped shut

• Difficult to reverse

• Can take 10-20 ejaculations to clear remaining sperm

Tubal Ligation

• Oviducts are cut, cauterized, or clamped shut

• Difficult to reverse

• ** Doesn’t effect menstrual cycle because hormones move through the blood

Castration

• Surgical or chemical procedure

• Female loses ovaries and male loses testes

Hysterectomy

• Surgical removal of the uterus

• Can be complete (remove entire uterus and cervix) or partial (cervix remains)

Comdom

• 15-30% Failure Rate

• Sheath that acts a barrier

• Prevents STIs

• Store in room temperature and away from sun and moisture

• Never use oil-based lubricants with latex condom

Diaphragm

• 80% Effective Rate

• Small cup filled with spermicide placed around cervix

• Barrier and chemical protection

• Must be fitted and ordered by doctor

Spermicides

• 80% (or less) Effective Rate

• Contains the chemical Non-Oxynol-9

• May spread HIB and other STIs

• Many Forms: Sponge, cream, jelly, foam, film

Intra-Uterine Device (IUD)

• 0.2-0.8% Failure Rate

• Small device placed in uterus to kill sperm

  • Must be put in/removed by doctor

  • Can be form for 5 (hormonal) -12 (copper) years

  • Once removed, fertility returns to normal

• 2 Types: Copper and Hormonal

  • Copper: Disrupts sperm mobility and damaging them so they can not join with egg

  • Hormonal: Thickens the cervical muscles to make it impenetrable to sperm and inhibit ovulation for some users

Bacterial Infections

• Chlamydia and Gonorrhea:

  • 80% females and 50-60% males have not symptoms

  • Itching, discharge, burning during urination

  • Untreated: Causes pelvic inflammatory disease in women or infertility

  • Treatment: Antibiotics

• Syphilis:

  • Primary Stage: Sore that lasts 3 to 6 weeks and heals regardless of treatment, but treatment is needed to avoid other stages

  • Second Stage: Rash, fever, swollen lymph glands, sore throat, hair loss, headaches, weight loss, muscle aches, and fatigue

  • Late Stage: 10-30 years after first infection with muscle difficulty, paralysis, blindness, and dementia, as well as damage to internal organs and death

• Can spread across the placenta and cause brain damage, seizures, and possibly death to fetus

Viral Infections

• HPV (Human Papilloma Virus):

  • Genital Warts

  • Spread by skin-to-skin contact

  • Can appear on genitals and look like cauliflower or no symptoms

  • Linked with throat cancer, cervical cancer (women), and penile cancer (men)

  • HPV vaccine available for girls and boys - almost 100% effective

• HIV (Human Immunodeficiency Virus):

  • Spread through contact with infected body fluids (blood, semen, vaginal fluid), unprotected sex, and sharing needles

  • Few symptoms until immune system is severely compromised

  • Ultimately is fatal

  • If used consistently & correctly, condoms are highly effective at preventing HIV

• Herpes:

  • Spread by skin-to-skin contact

  • Often no symptoms; sores on genitals & groin area

  • Antiviral medication can help alleviate/prevent outbreaks

  • Asymptomatic shedding (can spread the virus even if there are no symptoms)

• Hepatitis:

  • Inflammation in liver

  • Hepatitis B: Spread by contact with infected body fluids (vaccine available) and has symptoms of jaundice, abdominal pain, and fatigue

  • Hepatitis C: Spread by contact with infected blood such as through sharing needles, unprotected sex, and child birth (no vaccine yet) and 1-5% infected adults will die

    • Leading cause of liver transplants

Parasitic Infections

• Trichomoniasis:

  • Caused by parasite

  • Infects vagina or male urethra

  • Symptoms: Itching and smelly discharge

• Crabs & Scabies:

  • Spread through close (usually sexual) contact

  • Symptoms: Itching in the genitals (crabs) and scabs on the skin (scabies)

  • Cured by topical cream & many, many loads of laundry

Sterile

• Unable to have children

Infertile

• Difficulty conceiving

• Average time to conceive = 6 months (longer if individuals are older than 25)

• After 1 year of regular unprotected sex, if a couple hasn’t conceived, they are considered infertile

Causes of Male Sterility/Infertility

• Blocked Epididymis or Vas Deferens

  • Possible Causes: STIs

• Low Sperm Count

  • Possible Causes: Overheated testicles, smoking, alcohol

• High Proportion of Abnormal/Non-viable Sperm

  • Possible Causes: Overheated testicles, exposure to toxins or radiation, infections (STIs)

• Impotence

  • Possible Causes: Vascular disease, nervous system, injury, stress, hormonal imbalance, medication, smoking, alcohol

Causes of Female Sterility/Infertility

• Blocked Fallopian Tube

  • Possible Cause: STIs

• Failure to Ovulate

  • Possible Causes: Hormonal imbalances for many reasons, including malnourishment and stress

• Damaged Eggs

  • Possible Causes: Exposure to toxins or radiation

• Endometriosis

  • Endometrium tissue grows outside uterus Possible Causes: Genetics, hormone imbalance, immune factors, toxins

Intrauterine Insemination (IUI)

• Sperm are collected and concentrated → placed inside uterus

• Sperm may be from woman’s partner, or from another donor (sperm bank)

• Useful if: blocked vas deferens, low sperm count, or high proportion of non-viable sperm

Surrogacy

• Through IUI or IVF or both, infertile couple contribute gametes → baby is carried by another woman (surrogate mother)

• Useful if: pregnancy is impossible or dangerous to the health of a woman

Superovulation (Fertility Drugs)

• Hormone treatment stimulates production and ovulation of multiple eggs (2 – 4)

• Often used in combination with IUI

• Useful if: woman rarely or never ovulates

Vasectomy Reversal

• Reconnection of the Vas Deferens after vasectomy

In Vitro Fertilization (IVF)

• In glass fertilization

• 10-12 eggs close to ovulation are removed from follicles → Sperm and egg are combined in a petri dish (in vitro) → morula or blastocyst is placed into uterus

• Useful if: oviducts are blocked, or in combination with other technologies

IVF Procedure

• GnRH agonist given for 2 weeks to put female into a temporary state of menopause

• Ultrasound is given to ensure ovarian suppression is happening

  • Shut down woman’s hormones

  • No GnRH, FSH, or LH

  • No ovulation

• Large doses of FSH given for 9-14 days

• Follicular development is monitored by ultrasound every 2 days and checking estrogen levels

• Eggs are retrieved

  • Stimulate the follicles to produce eggs and estrogen

• A semen sample is collected 1-3 hours following egg retrieval

  • Fresh sample for maximum viability

• Once the eggs and sperm have been collected, ICSI or conventional insemination is done

  • Sperm injected directly into egg to ensure fertilization

• Progesterone id given the day after egg retrieval and continues for 10 weeks, if the pregnancy test is positive

  • Progesterone causes growth of endometrium and prevents contractions

• Embryo transfer is usually done on the 3rd or 5th day following egg retrieval

  • Morula or blastocyst is placed in uterus

  • Blastocyst is stage that implants

  • Make sure the egg is divided

• A blood test for pregnancy will be arranged for day 16 post embryo transfer if a transfer was done on day 3

  • Check if implantation was successful

  • If not, discontinue progesterone and try procedure again

Fertilization

• Occurs in the fallopian tube (within 24 hours of ovulation)

• Millions of sperm are released in ejaculation, but majority do not survive the acidic environment of the vagina, the female’s immune system, or go the wrong way

• Only a few dozen make it to the egg

  • The acrosome releases enzymes to digest the jelly-like coating surrounding the egg

  • The sperm membrane fuses with the eff membrane ant the sperm nucleus enters the egg

• One sperm cell will be able to penetrate the egg

  • The moment it does, the egg secretes substances which inhibit any other sperm from entering

• The egg undergoes meiosis II and releases a polar body

• The sperm nucleus (n) and the egg nucleus (n) merge to form a zygote (2n)

  • Zygote = First single cell of new life

Fertilization

1. Sperm Nucleus (n)

2. Egg Cell Membrane

3. Egg Nucleus (n)

4. Polar Body (n)

5. Zygote (2n)

Blastocyst

A cavity (space) appears

• Chorin: Trophoblast

  • Outer layer of blastocyst

  • Forms placenta and amnion

• Inner Cell Mass: Develops into embryo

Blastocyst Diagram

1. Inner Cell Mass

2. Chorin

3. Cavity

Ovulation to Implantation

Day 1: First Cleavage

• Cell divides by mitosis

Day 4: 16 – 32 cell stage

• Ball of cells is called a morula

Day 5:

• Cells begin to move around to form an inner and outer layer of cells

Day 6:

• Two layers of cells arrange themselves around a hollow fluid filled cavity (blastocoel)

• Actual cell mass is called blastocyst

Day 7: Implantation

• The blastocyst, by means of villi and enzymes secreted by the chorion (a membrane that forms around it), implants itself in the endometrium

• Results in pregnancy (gestation)

• The chorion secretes hCG (hormone), which stimulates the corpus luteum to produce progesterone and estrogen for the first 3 months

** Stem cells from the blastocyst are undifferentiated (totipotent) and can be used for stem cell research

Fertilization to Implantation Diagram

1. Zygote

2. Mitosis

3. Morula

4. Blastocyst

5. Chorion: Helps to implant and secretes human chorionic gonadotropin (hCG) for 3 months

6. hCG

7. Corpus Luteum: Produces estrogen and progesterone for 3 months

Fertilization to Implantation Summary

• Zebras Make Better Guacamole Every Friday

• Zygote: Day 0 (sperm + egg)

• Morula: Day 4 (16-32 cells)

• Blastocyst: Day 6 (implantation)

• `Outer layer (chorion) secretes hCG and form placenta

• Gastrula: Day 7 (3 germ layers - ectoderm, mesoderm, endoderm)

• `Neurulation: Formation of neural tube

• Embryo: Day 10 (Chorion starts to form placenta)

• Fetus: Week 8 (All major organ systems have started to develop)

Ectopic Pregnancy

• In an ectopic pregnancy, a fertilized egg has implanted outside the uterus (usually in the fallopian tube)

• Severe bleeding and possible death of the mother can result from this type of pregnancy

Pregnancy Hormones

• Outer layer of the blastocyst (the chorion) starts to secrete hCH when it implants in the endometrium (~ day 7)

• This causes morning sickness and is the hormone measured in a pregnancy test

Pregnancy Test

• Tests for presence of hCG in the urine (sometimes blood)

• hCG is similar to LH and keeps corpus luteum secreting progesterone and estrogen for 3 months

• Later on, the placenta secretes sufficient estrogen and progesterone

Pregnancy Hormones

1. hCG

2. Progesterone

3. Estrogen

Miscarriage

• For first 3 months progesterone and estrogen  comes from the corpus luteum

• The placenta starts making them after 3 months

• If the corpus luteum stops producing the hormones and the placenta does not start then miscarriage occurs

Gastrulation

• Around day 7

• The process in which the inner cell mass of blastocyst (single layer of cells)turns into 3 germ layers (ectoderm, mesoderm, endoderm)

• Blastocyst is now called a gastrula

• Cells begin to differentiate to form specific organ systems and are no longer stem cells

Ectoderm

• Outer

  • Skin (epidermis)

  • Nervous system

  • Eye and ear

Mesoderm

• Middle

• Skeleton, muscles, gonads (so many gonads)

Endoderm

• Inner

• Lining of the digestive and respiratory system, and endocrine glands (RED)

• Thyroid, parathyroid, adrenals, and pancreas

Neurulation

• Formation of neural tube

• Develops into brain and spinal chord

• Happens during the gastrula stage

Morphogenesis

• Biological process that causes an organism to develop its shape

• Ex. Formation of blastocyst, gastrula, germ layers, etc

Day 7-10 After Implantation

• Gastrulation begins

  • Major cellular reorganization into the three germ layers (the endoderm, ectoderm and mesoderm)

  • “Gastrula” stage is when different genes will be turned on to express different organs in the later stages of the pregnancy

Day 10-14 After Implantation

• Pregnancy fully established

• Amniotic cavity forms

• Yolk sac starts to form

• Embryo forms

• Chorion starts to form placenta

Day 15-21 After Implantation

• Emergence of the body plan

• “Primitive streak” starts to form (at site of Gastrulation)

• Neural groove forms (future brain and spinal cord)

Day 21 After Implantation

• Heart begins to beat

Week 4 After Implantation

• Eyes, ears, and lower limbs begin to develop

Week 5-8 After Implantation

• Teeth, palate, external genitalia begin to develop

Chorion

• Outer membrane of the blastocyst

• Secretes hCG for the first 3 months

• Fetal contribution to the placenta

• Gas/nutrient/waste exchange

Amnion

• Inner membrane

• Becomes fluid-filled sac that protects embryo from infection, impact, and temperature fluctuations

Allantois

• Forms the foundation of the umbilical cord

• Becomes part of the bladder

Yolk Sac

• In other animals, provides nutrients (not for humans)

• Small in humans and forms blood cells

Extraembryonic Structures

1. Chorion

2. Amnion

3. Embryo

4. Allantosis

5. Yolk Sac

6. Fetal Portion of Placenta

7. Maternal Portion of Placenta

Placenta

Allows exchange of some substances between mother and fetus

• From Mother: Umbilical vein carries nutrients oxygen, antibiotics viruses, drugs, alcohol

• From Fetus: Umbilical artery carries metabolic waste and carbon dioxide

• ** No exchange of blood cells

Formed when the villi from chorion extend into endometrium

• Not fully developed until the second trimester

Stores 2 important hormones:

• Estrogen and progesterone during the second trimester and third trimester

  • Progesterone prevents contractions

  • Progesterone and estrogen cause growth of the endometrium

Functions as lungs (exchange O2 and CO2), small intestine (provides nutrients), and kidney (removes nitrogenous waste - urea and urine)

Umbilical Cord

• Rope like structure that forms after 8 weeks

• Runs from belly button of fetus to placenta

• Contains 2 arteries and 1 vein

  • 2 arteries carry deoxygenated blood from fetus to mother

  • Vein carries oxygenated blood from mother to fetus

• Normally arteries carry oxygenated blood

• Only 2 exceptions are pulmonary artery and umbilical artery

1. Placenta

2. Chorion

3. Amnion

4. Cervical Plug (Mucus): Keeps Out Pathogens

5. Uterus

6. Amniotic Fluid

7. Umbilical Cord

8. Umbilical Vein (1 - Carries Oxygenated Blood)

9. Umbilical Arteries (2- Carries Deoxygenated Blood)

10. Cervix

11. Vagina

Embryo vs Fetus

• An embryo is considered a fetus after 8/9 weels when all organs have started to develop

First Trimester

• Month 1-3

• Development of germ layers (gastrulation)

• By 9th week: embryo = fetus

• Mainly organogenesis (development of organs)

• Sex develops

• Most susceptible to environmental factors such as teratogens

  • Teratogens (substances that increase chance of birth defects)

  • Most significant effect on brain and spinal cord (CNS)

  • Ex. Alcohol, tobacco, cannabis, lack of folic acid

• Chorion secretes hCG and corpus luteum continues to secrete progesterone/estrogen

• Sexual Development

  • The male and female sex organs originate in the abdominal cavity

  • By the 3rd month of embryonic development the genes on the sex chromosomes cause gonad tissue to specialize into testes or ovaries

• Boy

  • The Y chromosome carries a gene called the sex-determining region Y (SRY) that triggers the production of male hormones known as androgens (testosterone)

  • The presence of androgens starts the development of male sex organs in the fetus

• Male: Glans, penis, scrotum

• Female: Clitoris, labia minor, labia major (labia are folds that surround the urethral and vaginal opening

Second Trimester

• Mont 4-6

• Growth (mitosis) and refinement of tissues

• Organs continue to form, cartilage skeleton replaced by bone

• Fetus can survive outside womb at end of 6th month (with medical support) placenta secretes

Third Trimester

• Month 7-9

• Fetus grows rapidly

• Organ systems increase in size

• Fat is deposited

• Respiratory & circulatory systems become ready to allow for air breathing

• Testes descend into scrotum

• The mother’s bowels and organs det displaced due to pregnancy

Birth “Parturition” - Delivery

• 38 – 42 weeks from conception; average = 40 weeks

• Low levels of progesterone are crucial to labor onset

• High estrogen levels trigger oxytocin receptors in myometrium (muscular layer of the uterus)

• Rhythmic uterine contractions signal labor

• Cervix begins to dilate

• Amniotic membrane bursts (water breaks)

Birth Steps

1. Head of fetus pushes against cervix

2. Nerve impulses from cervix transmitted to brain

3. Brain stimulates pituitary gland to secrete oxytocin

4. Oxytocin carried in bloodstream to uterus

5. Oxytocin stimulates uterine contractions and pushes fetus towards cervix

Labour Hormones

• PROP

• Prostaglandins: Local area hormone (produced by uterus) that works with oxytocin causing uterine contractions

• Relaxin: Produced by placenta, relaxes ligaments in pelvis to ease passage of baby

• Oxytocin: Produced by hypothalamus and stored in posterior pituitary, positive feedback causes uterine contractions

• Prolactin: Produced by anterior pituitary, causes mammary glands to produce milk

Labour Feedback Loop

Stages of Labour

• Dilation: (Labour) Longest stage and can be many hours (2-20)

  • Uterine contractions and oxytocin cause the cervix to open or dilate

  • Amniotic sac breaks and the amniotic fluid is released through the vagina

• Expulsion: (Delivery) Lasts from 0.5-2 hours

  • Forceful contractions push the baby through the cervix to the birth canal

  • As the baby moves through the canal, the head rotates and makes it easier for the body to pass through

• Placental Delivery: (Afterbirth) Lasts from 10-15 minutes

  • After the baby is born

  • Placenta and umbilical cord are expelled from the uterus

Episiotomy

• Incision is made with a scalpel to increase size of vaginal opening

Cesarean Section

• Incision in abdomen and uterus

  • Useful for babies in the rump first position and form moms with STDs

Epidural Analgesia

• Needle inserted into the epidural space in the side

  • Provides pain relief during labour by blocking sensory pain receptors (neutral pathway)

  • Numbs from the waist down

  • Provides anesthesia for episiotomy or forceps for delivery

  • Avoids slowed heart rate of baby and mom (which can be dangerous) – other pain killers maypossibly cause this

Lactation

• Breast Feeding

• Lactation is the production and secretion of breast milk.Colostrum: yellowish fluid produced by mammary glands during first days after birth

• high in protein and antibiotics to protect baby

• Prolactin is produced (anterior pituitary) after birth when levels of estrogen and progesterone drop

  • It initiates milk production

Post Birth Hormones

1. Estrogen

2. Progesterone

3. Prolactin

Lactin and Oxytocin

1. Suckling stimulates nerve endings in nipple and areola of breast

2. Neural pathways carry stimuli to hypothalamus

3. Hypothalamus produces oxytocin that is released by posterior pituitary

4. Oxytocin carries mammary lobules to contract

5. Milk letdown occurs

Chorionic Villus Sampling

• A thin tube is guided through the cervix or a needle is inserted into the uterus to remove a sample of chorionic villus cells from the placenta for genetic testing

• Detects Downs’ Syndrome, Cystic Fibrosis etc.

• Can be performed after 9th week

Amniocentesis

• Needle withdraws amniotic fluid sample containing fetal cells

• Genetic, karyotyping, or hormone tests

• Can be performed after 14th week

• 99% + accuracy in diagnosing neural tube defects such as spina bifida

Ultrasound

• A diagnostic technique which uses sound waves sent through body are used to visualize internal structures

Karyotype

• Chromosome map that detects disorders like down’s syndrome

Gel Electrophoresis

• Gene mapping

• Detects abnormalities in DNA

• Steps:

  • Load samples of DNA fragments into wells at the top of the gel

  • Apply electric field

  • Wait additional time

    • Higher mass molecules will stay at the negative end while lower mass will move to the positive end

    • Each band is a group of DNA fragments with the same mass