(8.1) Implantation Flashcards
Describe the process of implantation.
- 4th week: Blastocyst enters uterine cavity -> Trophoblasts (outer Syncitiotrophoblast + inner Cytotrophoblast) invade uterine endothelium
- 10th week: complete interstitial implantation (foetal vessels project villi into mesenchyme)
Suggest things that are transported across Placenta, how are they each transported?
- Passive Diffusion: gases, water, electrolytes, urine, uric acid
- Facilitated Diffusion: glucose
- Active Transport: amino acid, iron, vitamins
- Teratogens: alcohol, smoking, therapeutic drugs (e.g. Thalidomide, Wafarin)
- Infectious pathogens: Varicella zoster, Rubella, Cytomegalovirus, Treponema pallidum, Toxoplasma gondii
What are Teratogens? List some examples of them.
- Substances transport across Placenta -> Foetal damage
- Alcohol
- Maternal smoking
- Wafarin
- Thalidomide
What are the aims of implantation?
- Anchor Placenta
- Establish maternal blood flow within Placenta
- Establish exchange unit via foetal vessels projecting like villi into Placenta
Describe the structure of Placenta.
- Chorion Frodosum forms the foetal portion
- Ducidua Basalis forms the maternal portion
- Chorionic and Ducidual Plates mark the boarder and the forms the Intervillous spaces in between, which is filled with maternal blood
- Ducidual Septae separate Placenta into Cotyledons
Describe the arrangement of foetal blood vessels within Placenta.
- Spiral arteries remodel -> low resistance -> high blood flow & pressure -> force oxygenated blood filling Intervillous spaces
- 2 x Umbilical veins -> OXYGENATED blood from Intervillous spaces to baby
- 1 x Umbilical artery -> DE-oxygenated blood from baby to mom
Describe the histology changes and roles during implantation.
- Dicidualisation - Ducidual cells -> Placenta: balance invasive force from Trophoblasts
- Spiral arteries remodel -> low resistance -> meet high blood flow demands
Describe the difference between First Trimester Placenta and Term Placenta.
- First Trimester Placenta: thick
- Term Placenta: loss of Syncitiotrophoblasts
What do Ducidual Septae separate Placenta into?
Cotyledons
Describe the space between Chorionic and Ducidual Plates.
- Intervillous spaces
- Filled with maternal blood from remodelled Spiral arteries
What structure is the foetal portion of Placenta derived from?
Chorion Frodosum
What structure is the maternal portion of Placenta derived from?
Ducidua Basalis
How is the trimester of pregnancy divided?
- 1st: week 1 - 12
- 2nd: week 13 - 28
- 3rd: week 29 - 40
What is Ducidualisation? How is it initiated? What is the aim of this and what happens if it fails?
- Ducidual cells -> Placenta
- Stimulated by Progesterone (from Corpus Luteum first 2 months -> Placenta)
- Balance invasion force of Trophoblasts
- Failure -> harmorrhage
Suggest three locations that Ectopic Pregnancy may take place?
- Fallopian Tube - most common
- Peritoneal cavity
- Ovary
What is it called when the Blastocyst is implanted at lower portion of Uterine? How is it managed?
- Placenta Praevia
- C-section delivery
What is tested in the urine during Antenatal Screening? Why is it tested?
- Protein
- High protein levels indicates Pre-Eclampsia
Describe the endocrine function of Placenta.
- Progesterone (takes over Corpus Luteum in week 2)
- Oestrogen
- Human Chorionic Gonadotrophin
- Human Chorionic Somatotrophin
- Human Chorionic Corticotrophin
What produce Human Chorionic Gonadotropin? What is its function?
- Syncitiotrophoblasts
- In the first 2 weeks to maintain Corpus Luteum -> production of Progesterone -> enriches Uterine vasculatures
What is the role of Human Chorionic Somatotropin?
Interferes maternal metabolism -> Increase Glucose availability
What other substances except from hormones does the Placenta produce?
- Glycogen
- Cholesterol
- Fatty acids
What is tested during hormonal pregnancy test?
- Human Chorionic Gonadotrophin
- In maternal urine
- During first 2 months of pregnancy
How does the foetus receive passive immunity?
- Foetus makes its own components of complement in late T1
- Receptor Mediated Pinocytosis
- IgG transported from mom to foetus in Week 14
Describe the endocrine function of Placenta.
- Progesterone (takes over Corpus Luteum in week 2)
- Oestrogen
- Human Chorionic Gonadotrophin
- Human Chorionic Somatotrophin
- Human Chorionic Corticotrophin
- Human Chorionic Thyrotrophin
What is the role of Human Chorionic Somatotropin?
Reduce Insulin sensitivity of mother -> Increase Glucose availability
What substances except from hormones does the Placenta produce?
- Glycogen
- Cholesterol
- Fatty acids
What are the main functions of the Placenta?
- Metabolic: synthesis of Glycogen & Cholesterol & Fatty acids
- Endocrine: hCH, hCS, hCC, hCT, Progesterone, Oestrogen
- Transport: water, nutrients, IgG
Describe how the maternal blood flood is established to the foetus?
- Invasion of Syncitiotrophoblasts -> Lacunae
- Lacunae enlarges -> Primary Villi = including both types of Trophoblasts
- Continuous development of these projections -> Secondary Villi = Mesenchyme core
- Tertiary Villi = Foetal vessels
Suggest three infectious agents which across the Placenta.
- Rubella
- Varicella zoster
- Cytomegalovirus
What is Haemolytic Disease of the newborn?
- Mother = Rhesus -ve
- Foetus = Rhesus +ve
- IgG across placenta -> destroy foetal RBCs
What is thought to be the underlying pathology of Pre-eclampsia?
Inadequate modification of vessel walls during invasion
How does Pre-eclampsia manifest?
- Increased blood pressure (V. important)
- Proteinuria (V. important)
- Pitting oedema
- Headache/blurred vision
- Liver distension (RUQ pain)
- Oligouria - kidney fucked
