Block 11 Week 1 Flashcards
(74 cards)
Foetal development up to 12 weeks
Day 0 - fertilization in ampulla - zygote
Day 0-4: mitosis keeps happening
We end up with the morula (16 cells) by day 4
Day 6: implantation in uterus. Now called Blastocyst
Within the first week the cells of the morula reorganise to form a cavity, known as the blastocyst cavity ( blastocoel). Some of the cells move towards the outer edge ( form the outer cell mass) and another group together (inner cell mass).
Trophoblast – the outer cell mass. Trophoblast contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta.
Embryoblast - Responsible for the formation of the embryo itself.
From this point the morula is known as the blastocyst.
During the second week the trophoblast and embryoblast divide into increasingly specialised cells.
Trophoblast (outer cell mass) - syncytiotrophoblast (multinucleated) and cytotrophoblast (mononucleated)
Embryoblast (inner cell mass) - epiblast and hypoblast (bilaminar disc), forming a two layered structure called the bilaminar disc.
The amniotic cavity forms within epiblast.
What will the epiblast and hypoblast become?
Epiblast: Amniotic sac
-The epiblast develops into the endoderm, mesoderm, and ectoderm.
Hypoblast: Yolk sac
-The yolk sac is initially responsible for fetal nourishments and circulation between the mother and fetus (before the placenta develops).
B-hcg
Synctiotrophoblast makes something called B-hcg which is the chemical we use to detect pregnancy in pregnancy test
Ectopic pregnancy and placenta previa
- foetus growing in fallopian tube. Not viable pregnancy
- placenta previa: foetus is growing too low down in the uterus so when it comes to birth their will be complication s as the umbilical chord will be in the way
GASTRULATION
- week 3 is when gastrulation occurs
- we end up forming our 3 germ layers: ectoderm, endoderm, and mesoderm
notochord = nucleus pulposus
neural plate = brain and spinal chord
- folic acid is important for neural tube development
Gastrulation involves the migration, invagination and differentiation of the epiblast. It is largely controlled and orchestrated by the primitive streak.
Primitive streak = primitive groove
Primitive node = primitive pit
The epiblast cells migrate through the primitive groove and towards the hypoblast cells (invagination), they then replace these hypoblast cells. This layer is now called the Endoderm.
More epiblast cells migrate and move down and laterally (ventrally) through the primitive groove and form the mesoderm layer.
We now call the top layer of epiblast cells the Ectoderm
Epiblast – Ectoderm
New layer – Mesoderm
Hypoblast – Endoderm ( they are at the bottom the –end)
The three germ layers are called multipotent and can differentiate into any cell type, they are responsible for forming different tissues in the foetus.
The notochord forms from the mesoderm cells soon after gastrulation is complete.
Neurulation
Neurulation is the process by which ectoderm in the trilaminar embryo develops into the neural tube ( neuroectoderm tube) which is the basis for the nervous system.
Notochord: induces differentiation of overlying ectodermal cells above it to form neural plate
Neural plate ( made of ectoderm): thickening of ectoderm along the midline which causes a depression to form in the centre of neural plate. This is called the neural groove.
The neural folds circle upward and meet in the midline, forming a tube
This tube is pulled below the outer layer of ectoderm → now known as the neural tube
Neural crest cells separate and are located between the neural tube and the ectoderm.
Surface Ectoderm = Epidermis
Neural crest cells = peripheral nervous structures
Neural tube = CNS
At this point the primitive node and the primitive streak begin to fade.
Week 4
- major organ development begins around week 3-4
Week 4:
- neural tube closes
- heart beats ( 4 chamber heart)
- limb formation (4 limbs)
Week 8
- Week 8 we have foetal movement and start referring to our baby as foetus not embryo. ( 8 ‘gait’)
- Week 10: sex of the foetus is recognisable (genitalia - tenitalia)
Describe events during fertilization ?
- Fertilization usually takes place in the fallopian tubes, where the egg awaits the arrival of sperm.
- The sperm must then penetrate the protective layers surrounding the egg. The outer layer of the egg, called the zona pellucida, is broken down by enzymes released by the acrosome, a cap-like structure at the tip of the sperm.
- Once the sperm penetrates the zona pellucida, it binds to the egg membrane. The membranes of the sperm and egg fuse, allowing the genetic material (chromosomes) from both the sperm and the egg to combine.
- The fusion of the sperm and egg results in the formation of a single-celled structure called a zygote. The zygote contains a complete set of chromosomes, half from the mother and half from the father
- The zygote undergoes rapid cell division through a process called cleavage. As the cells divide, a blastocyst is formed.
Ethics around assisted reproduction
- Assisted reproduction refers to medical procedures that aid in the conception of a child. These procedures can include in vitro fertilization (IVF), intrauterine insemination (IUI), surrogacy, and various fertility treatments.
-Respect for Autonomy: Individuals and couples undergoing assisted reproduction should have the autonomy to make decisions about their reproductive choices. Informed consent is crucial, ensuring that individuals understand the potential risks, benefits, and alternatives associated with the procedures.
- Status of the Embryo: The status of the embryo is a complex ethical issue. Some people believe that life begins at conception, while others may have different views. Decisions about the disposition of embryos (e.g., freezing, donation, or disposal) can be ethically challenging.
- Rights and Responsibilities: Surrogacy raises questions about the rights and responsibilities of all parties involved—intended parents, gestational carriers, and the child. Ethical considerations include the potential for exploitation, the well-being of the surrogate, and the rights of the child.
- The use of fertility treatments can result in multiple pregnancies, which may pose health risks to both the mother and the fetuses. Decisions about selective reduction (reducing the number of fetuses) can involve ethical dilemmas.
-Avoiding Exploitation: There are concerns about the commercialization of assisted reproduction and potential profiteering. Ethical guidelines aim to prevent the exploitation of vulnerable individuals or the commodification of human reproductive capacities.
Resource management in NHS ?
The NHS provides a range of services related to fertility, maternity, and prenatal care
- Preconception Care:
GP Consultations: Schedule preconception consultations with your General Practitioner (GP). They can provide advice on preconception health, address any concerns, and ensure that you are in good health before trying to conceive.
Folic Acid and Vitamin Supplements: GPs often recommend folic acid supplements for women trying to conceive to reduce the risk of neural tube defects in the baby.
Fertility Services:
Fertility Assessment: If you experience difficulty conceiving, the NHS offers fertility assessments and treatments. Consult your GP to discuss your situation, and they can refer you to a fertility specialist if necessary.
Fertility Testing and Treatments: Some fertility testing and treatments may be available through the NHS. The availability and eligibility criteria may vary depending on your location.
Antenatal and Maternity Services:
Booking Appointments: Once pregnant, contact your GP to book your first antenatal appointment. This is the beginning of your maternity care journey within the NHS.
Midwifery Care: Maternity care in the NHS involves midwifery support. Midwives provide care during pregnancy, labor, and the postpartum period.
Ultrasound Scans: Routine ultrasound scans are part of NHS antenatal care to monitor the baby’s development and ensure a healthy pregnancy.
Health Visiting and Postpartum Support:
Health Visitor Support: Health visitors provide support and advice on various aspects of infant care, development, and well-being after the baby is born.
Postnatal Care: NHS offers postnatal care to monitor the health of both the mother and the baby. This includes postnatal check-ups and support for breastfeeding.
Parental and Maternity Leave:
Understanding Leave Policies: Be aware of your rights regarding parental and maternity leave. Understand the policies in your workplace and how they align with statutory rights in the UK.
Financial Support:
Maternity Allowance: Explore potential financial support, such as Maternity Allowance, which may be available if you do not qualify for Statutory Maternity Pay through your employer.
Benefits and Entitlements: Understand other benefits and entitlements available to families, such as Child Benefit and Tax-Free Childcare.
Prenatal Classes and Support Groups:
NHS Antenatal Classes: Consider participating in NHS antenatal classes, which provide information and support for expectant parents.
Support Groups: Joining local support groups or online communities can provide additional emotional support and information.
Psychological treatment for IVF patients ?
- Individual Counseling: One-on-one counseling sessions with a psychologist or therapist can provide a private and supportive space for individuals to express their emotions, fears, and concerns related to infertility and IVF.
Couples Counseling: Couples may benefit from joint counseling sessions to enhance communication, cope with stress, and navigate the emotional challenges of fertility treatments together - Psychoeducation: Providing information about the IVF process, potential challenges, and coping strategies can empower individuals and couples. Knowing what to expect and understanding the medical aspects of treatment can reduce anxiety.
Decision-Making Support: Psychologists can assist in decision-making processes, such as whether to continue with additional fertility treatments or explore alternative family-building options - IVF Support Groups: Joining a support group with other individuals or couples going through IVF can offer a sense of community and shared understanding. It provides an opportunity to share experiences, coping strategies, and emotional support.
Online Communities: In addition to in-person support groups, online forums and communities can connect individuals with others facing similar challenges. This can be particularly beneficial for those who prefer virtual interactions.
Pharmalogical treatment for ovulation induction ?
- Ovulation induction is a medical intervention aimed at stimulating the ovaries to produce and release eggs, particularly in cases of infertility where ovulation is irregular or absent
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Oestrogen and FSH relationship
- FSH and LH causes eostrogen production by binding to the theca and granulosa cells on the follicle
- As oestrogen level rise it has a negative feedback effect and causes a decrease in FSH from the anterior pituitary gland.
- As a result of the decrease on FSH some developing follicles will stop developing and die off
- The follicles with the most FSH receptors will continue to grow - dominant follicle - undergo ovulation.
- The dominant follicle continues to secrete oestrogen
-Oestrogen makes pituitary gland more responsive to GnRH so ir releases more FSH and LH ( now oestogen is acting as a positive feedback mechanism)
- The surge in FSH and LH happens 1-2 days before ovulation.
It is responsible for the rupture of the ovarian follicle and release of the oocyte.
Clomiphene Citrate
Clomiphene Citrate (Clomid):
Mechanism of Action: Clomiphene citrate is a selective estrogen receptor modulator (SERM). It works by blocking estrogen receptors in the hypothalamus and pituitary gland, leading to increased secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This, in turn, stimulates ovulation.
Administration: Typically taken orally for a specific number of days during the menstrual cycle.
Letrozole ( Femara)
Letrozole (Femara):
Mechanism of Action: Letrozole is an aromatase inhibitor that reduces estrogen production, leading to an increase in FSH and subsequent ovulation.
Administration: Usually taken orally for a specified number of days in the early part of the menstrual cycle.
Gonadotropins
Gonadotropins:
Types: Injectable gonadotropins, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), can be administered to stimulate the ovaries directly.
Administration: Administered by injection, typically subcutaneously or intramuscularly. The dosage and timing are closely monitored to prevent complications like ovarian hyperstimulation syndrome (OHSS).
Human Chorionic Gonadotropin (hCG)
Human Chorionic Gonadotropin (hCG):
Mechanism of Action: hCG is often used in conjunction with other medications to trigger ovulation. It mimics the action of LH, inducing the release of mature eggs from the follicles.
Administration: Administered as an injection after the development of mature follicles, timed to coincide with the expected time of ovulation.
Metformin
Metformin:
Indications: Metformin is commonly used in the treatment of polycystic ovary syndrome (PCOS) and insulin resistance, which can contribute to ovulatory dysfunction.
Mechanism of Action: It helps regulate insulin levels, which, in turn, can normalize ovarian function and promote regular ovulation.
Bromocriptine or Cabergoline
Bromocriptine or Cabergoline:
Indications: These medications may be prescribed in cases where elevated prolactin levels are causing ovulatory issues.
Mechanism of Action: They reduce prolactin levels, helping to restore normal ovulation.
Aromatase Inhibitors
Aromatase Inhibitors (Anastrozole):
Indications: Aromatase inhibitors are sometimes used as an alternative to clomiphene citrate for ovulation induction.
Mechanism of Action: Similar to letrozole, they inhibit the production of estrogen, indirectly stimulating the release of FSH and promoting ovulatio
Limitations of assisted reproduction techniques ?
While assisted reproduction techniques have provided hope and solutions for many couples struggling with infertility, they also come with certain limitations and challenges. Here are some notable limitations of assisted reproduction techniques (ART):
Success Rates:
Varied Success Rates: Success rates for ART can vary widely depending on factors such as age, underlying fertility issues, and the specific technique used. While many couples do achieve successful pregnancies, there is no guarantee of success in every case.
Financial Costs:
Expense: ART procedures, including in vitro fertilization (IVF), can be expensive. The financial burden may limit access for some individuals or couples, and insurance coverage for these treatments may vary.
Emotional and Psychological Stress:
Emotional Strain: The emotional toll of fertility treatments can be significant. The uncertainty, repeated cycles, and the potential for both success and failure can contribute to stress, anxiety, and depression.
Multiple Pregnancies:
Risk of Multiple Births: Fertility treatments, particularly the use of ovulation-inducing medications and assisted reproductive technologies, increase the risk of multiple pregnancies (twins, triplets, etc.). Multiple pregnancies carry higher risks for both mothers and babies.
Ovarian Hyperstimulation Syndrome (OHSS):
Complications from Medications: Ovulation-inducing medications, particularly injectable gonadotropins, can lead to ovarian hyperstimulation syndrome, a potentially serious condition characterized by enlarged ovaries and fluid imbalances.
Ethical and Legal Issues:
Ethical Considerations: Some people may have ethical concerns related to the creation, selection, and disposition of embryos, as well as issues surrounding surrogacy and reproductive technologies.
Legal Complexities: Legal issues can arise in cases of gamete donation, surrogacy, and custody disputes involving assisted reproductive technologies.
Limited Treatment Options for Some Conditions:
Certain Infertility Causes: Some medical conditions or infertility factors may not be amenable to treatment with existing assisted reproduction techniques. For example, severe male factor infertility or certain structural abnormalities may limit treatment options.
Age-Related Factors:
Diminished Ovarian Reserve: As women age, the quantity and quality of their eggs decrease, impacting the success rates of ART. Advanced maternal age is associated with lower chances of success and a higher risk of chromosomal abnormalities.
Health Risks and Side Effects:
Medical Complications: Fertility treatments carry some health risks, such as ectopic pregnancies, gestational diabetes, and high blood pressure during pregnancy. Additionally, there can be side effects associated with the use of hormonal medications.
Limited Control Over Genetic Factors:
Genetic Issues: ART does not guarantee the absence of genetic abnormalities in embryos. Pre-implantation genetic testing (PGT) can be used to screen embryos for certain conditions, but it is not foolproof.