Pregnancy, Parturition and lactation Flashcards
Where does fertilisation occur?
In the ampulla
What connects the fimbriae and ampulla to the uterus?
The isthmus
What is surrounded by granulosa cells?
The oocyte
How do cilia and smooth muscle aid fertilisation?
The oocyte has to travel through a physical gap between the fimbriae and the ovary.
Cilia and smooth muscle aid the gap jump
Describe sperm capacitation in the female reproductive system
Attachment of the acrosome to attachment proteins on the egg
Membrane of sperm and oocyte fuse
Penetration causes an increase of calcium
What does the increase in calcium levels trigger in sperm capacitation?
Triggers the second mitotic division
What attachment proteins does the acrosome attach to?
ZP3 (zona pellucida 3)
Function of the oocyte cortical reaction?
Penetration to trigger the second meiotic division
Prevents polyploidy
What does haploid pronuclei fusion form?
A diploid zygote
Describe pre-implantation.
Conceptus in the oviduct, undergoing mitosis, lasts 3 days ->
Morula is formed after 3 days (solid mass of 12 cells) ->
Morula forms a blastocyst ->
Blastocyst become implanted after 6 days
Function of trophectoderm?
Forms further structures in embryo
Function of the fluid filled inner mass?
The inner mass becomes the embryo
What are the stages of endometrium invasion?
- Hatching
- Apposition
- Adhesion
- Invasion
What are the stages of endometrium invasion?
- Hatching
- Apposition
- Adhesion
- Invasion
Describe the stages of endometrium invasion
- Hatching
- Zona pellucida disintegrates - Apposition
- Cell bodies line up alongside endometrial tissue - Adhesion
- Integrin proteins attach between maternal and endometrial tissue and the conceptus - Invasion
- The blastocyst outer layer invades endometrial tissue to form the inner cytotrophoblast and the outer syncytiotrophoblast
How is the decidua formed?
The blastocyst promotes endometrial stromal cells to form decidua (predecidualisation)
What does the decidua contain?
Glands and immune cells
Blood and lymph vessels
Glycogen for nourishment
Function of the decidua?
Reduces inflammation
Decreases rejection of the allogenic embryo
When does the placenta form?
After attachment of embryo in the uterus
What structure do cytotrophoblasts and syncytiotrophoblast form?
Villi and microvilli projecting into the maternal blood
What is maternal and foetal blood separated by in mature placenta?
Foetal capillary endothelium
Mesenchyme
Cytotrophoblasts
Syncytiotrophoblast
Why does the placenta contain fluid-filled cavities?
The cavities fill with blood and cause a reduction in the force and velocity of pulsile blood from the mother
How is glucose transported from maternal to foetal blood?
Facilitated diffusion
How are amino acids transported from maternal to foetal blood?
2nd degree active transport
How are vitamins transported from maternal to foetal blood?
Active transport
How are LDL, hormone and antibodies transported from maternal to foetal blood?
By receptor mediated endocytosis
What is oxygen exchange between maternal and foetal blood facilitated by?
Foetal haemoglobin has a higher affinity for oxygen
What is lacune?
Blood collected into venules to form veins without a capillary phase
How are creatinine and waste urea transported from foetus to mother?
Diffusion from amniotic fluid, removed by maternal blood
What are the changes in hormones during trimester 1?
HCG is at its highest on day 8, stimulates production of progesterone, oestrogen and prolactin (stimulate corpus luteum)
LH rescues the corpus luteum
What are the hormonal changes in trimester 2 and 3?
HCG coordinates glucose to FA, ketone storage and mammary gland development.
Progesterone synthesised from circulatory cholesterol
Oestrogen synthesises foetal placenta
How is progesterone synthesised in the foetus?
Cholesterol moves into the placenta ->
Cholesterol turns into pregnenolone ->
Pregnenolone turns into progesterone in the placenta and then moves into the foetus
How is estriol synthesised?
Cholesterol from the mother moves into the placenta ->
Cholesterol turns into pregnenolone ->
Pregnenolone transfers into the foetus ->
The foetal adrenal gland catalyses pregnenolone to DHEA-sulfate ->
The foetal live catalyses DHEA-sulfate to 16-OH-DHEA-sulfate ->
This transfers back to the placenta as estriol
What is the parturition stage 0?
From conception to initiation of parturition
Describe what happens in parturition stage 0.
Uterus relaxes and is insensitive to uterotonic hormones
Progesterone supresses myometrial contractions
Braxton hicks contractions occur
When can Braxton hicks contractions take place?
Once the uterus has reached a critical size
What is parturition stage 1?
Preparation for birth, prior to labour
What happens in parturition stage 1?
Upregulating HP adrenal axis causes a cortisol release ->
This upregulates oestrogen and progesterone ratio, increasing contractility of myometrium ->
Oestrogen stimulates the release of prostaglandin
Function of prostaglandin
Promotes gap junction formation
What happens to the cervix during parturition stage 1?
The cervix softens, thins and dilates
What genes are expressed during parturition stage 1?
Contraction associated proteins give muscle tone to the uterus and has receptors for oxytocin
What enzymes are released during cervical gene expression?
Enzymes that hydrolyse collagen matrix to soften
What is parturition stage 2?
Stimulation/labour/birth
Function of oxytocin during stage 2 parturition?
Causes contractions
What are the stages of labour and delivery?
- Dilation
- Pelvic ligaments relax, softening and widening - Expulsion of foetus
- Oxytocin levels increase - Placental
- Placenta detaches from decidua
What is parturition stage 3?
Recovery from birth
What happens in stage 3 parturition to prevent haemorrhage?
Vasoconstriction of spiral arteries
How long does the endometrial cycle take to re-establish after birth?
3-5 months
What is colostrum?
The first milk
- High fat and protein content
- Antibodies
What is milk?
A fat emulsion in aqueous solution
- Sugar
- Protein
- Cations and anions
Structure of a breast?
Alveoli - secretory breast unit
Contractile myoepithelial cells and adipose tissue
How is lactation controlled by hormonal control during pregnancy?
Oestrogen and progesterone promote breast growth and development ->
Oestrogen stimulates prolactin which produces milk (lactogenesis) ->
This usually promotes breast growth but this is inhibited during pregnancy
Where is prolactin stimulated?
In the anterior pituitary
How is lactation controlled by hormones postpartum?
Mammogenic - promotes cell proliferation (oestrogen)
Lactogenic - initiates milk production (prolactin)
Galactokinase - stimulates myoepithelium contraction (oxytocin)
Galactopoietic - maintains milk (prolactin and cortisol
What hormone inhibits the ovarian cycle?
Downregulation of GnRH
What inhibits dopamine release from hypothalamus?
Prolactin
