Endocrinology of Pregnancy Flashcards
Which role do oestrogens and androgens play in the efferent ducts and the epididymis of the male reproductive tract?
Oestrogens induce tubular fluid reabsorbtion –> to make a concentrate
Androgens induce nutrient secretion into the seminal fluid (for journey) in the epididymis
Which glands make the seminal fluid?
Mainly from accessory sex glands
- prostate gland
- seminal vesicles
- bulbourethral gland
–> Only little contribution of Epididymis/testis –> spermatozoa
Which changes does the spermatozoa undergo in the female reproductive tract?
What is the significance?
It undergoes changes that enable spermatogenesis:
- Capacitation
- loss of glycoprotein coat
- changes in surface membrane characteristics
- “whiplash” movement of tail –> peitschenartig
What is capacitation?
Changes that make spermatozoa able to fertilise ovum including
- Loss of glycoprotein ‘coat’
- Change in surface membrane characteristics
- Develop whiplash movements of tail
Where does capacitation take palce?
in ionic & proteolytic environment of the Fallopian tube
Which factors are needed for capacitation?
It is
- Ca2+ and
- oestrogen dependant –> needs female reproductive tract
What is the acrosome reaction?
The reaction, the acrosome of a sperm undergoes to penetrate the hard shell of the ovum (the Zona Pellucida)
What happens during the acrosome reaction?
- Initiation: Sperm binds to sperm receptor (ZP3)
- Ca2+ influx into sperm (progesterone mediated)
- Induces a release of hyaluronidase + proteolytic enzymes to
- penetrate the Zona Pellucida
Which hormone is needed for the acrosome reaction?
Ca2+ influx into sperm (neede for release of protein) is progesterone dependant
What happens when an ovum gets fertilised?
It changes its Zona Pellucida to prevent further binding + fertilisation by sperm (as no receptors are there anymore)
Mediated by a release of cortical granules (like ZP2 & 3)
What is the Conceptus?
It is the derivate of zygote –> everything that derivates from zygote (including embryus and extracellular (placental) parts)
How long does the free living phase of the conceptus last?
What is is supplied by during that time?
Can last up to 9-10 days (3-4 days until reached uterus)
–> Receives nutrients from uterine secretions
Explain the different phases of the blastocyte in the uterus
- Attachment phase
- outer trophoblast cells contact uterine surface epithelium
- Decidulisation phase
- changes in underlying uterine stromal tissue (within a few hours)
Which hormonal and non-hormonal factors influence implantation of the blastocyte in the uterus?
- LIF = Leukaemia inhibitory factor
- secreted by endometrial secretory glands
- stimulates adhesion of blastocyst to endometrial cells
- IL 11
- also from endometrial cells is released into uterine fluid, and may be involved
- Required progesterone dominance in presence of oestrogen
Explain the effects of progesterone on the endometrium in Decidualisation
Decidualisation= changes of endometrium after adhesion of blastocyst
Progesterone influences
- glandular epithelial secretion
- glycogen accumulation in connective tissue cells (stroma cells)
- increase vascularisation –> growth of capillaries
- increase permeability –> oedema
Which hormonal and non-hormonal changes are involved in the decidualisation?
- Progesterone changes endometium
- IL 11 involved
- many more (e.g. histamine, certain prostaglandins etc.)
What are the 4 main hormones that change during pregnancy?
How do they change?
All are elevated
- oestrogens (mainly oestriol)
- progesterone
- hCG (expecially in first few weeks)
- human placental lactogen
Explain the site of production of oestrogen during pergnancy
In first 40 days –> produced in corpus luteum (maintained by hCG binding to LH-receptors on corpus luteum)
than production taken over by placenta
Why does the corpus lutem goes on making oestrogens in the first 40 days of pregnancy and does not die?
Because hCG binds to the LH recptors on the corpus luteum –> stimmulates oestrogen production
Explain the levels of LH and FSH (GnRH) during pregnancy
LOW: LH and FSH levels are inhibited (-ve feedback) by oestrogen production
What is the role of oestrogen in the first 40 days of pregnancy?
It is essential for developing the fetalplacental unit
Explain site of production and levels of hCG during pregnancy
hCG= human chorionic gonadotrophin
- produced by trophoblasts (outside layer of blastocyte)
- Levels are elevated throughout pregnancy but expecially high in the first weeks
What is the role of hCG during pregnancy?
Stimmulates the corpus luteum in first weeks to make oestrogen
stimmulates the thyroid (causes decrease in TSH)
What is the main substrate for oestrogensproduction in pregnancy?
Maternal + Fetal DHEAS (Dehydroepiandrosterone)
Which hormones increase during pregnancy?
- ACTH –> adrenal sterioids
- Prolactin (not suitable for measurements of prolactinomas)
- IGF1 (stimulated by placental GH-variant)
- Iodothyronines –> hCG stimmulation of thyorid
- PTH related peptides (calcium for bone growth)
Which hormones decrease physiologically during pregnancy?
- Gonadotrophins
- LH + FSH –> -ve feedback of high oestrogen levels
- Pituitary GH
- TSH (hCG does the job, in replacement more THS needed)
Which hormones are involved in partuiton?
Oestrogen
Oxytocin
Cortisol
What are the roles of oxytocin in labour
Uterine contraction
Cervix dilation
Milk ejection (no milk production)
Explain the endocrine controll of lactation
How does prolactin influence the reproductive axis?
It binds to the receptors Kisspeptin neurons that downregulates kisspeptin leves and therefore downregulates GnRH
(also same way as oestrogen)
Which hormones induce labour?
- Oxytocin
- Cortisol
- Oestrogen
Explain the role and site of production of cortisol during partuition
The fetus produces fetal cortisol (via fetal arenals) and induces partuition(?)
Explain the role and MOA of oxytocin during partuition
Oxytocin binds to oxytocin receptors and causes Ca2+ influx –> uterine contraction
It also causes:
- cervical dilation
- milk let down
What is the role and site of production of oestrogen during partuition?
Are produced in the placenta and causue
- Ca2+ release from the myometrium and endometrial cells
- amplification of oxytocin effect –> uterine contractions
List 3 oestrogens produced, and state which one is produced in highest quantities during pregnancy
oestrone (E1)
17 beta oestradiol E2
oestriol –> Highest (E3)
Summarise the things happening during the attachment phase
- Outer trophoblast cells contact uterine surface epithelium.
- Leukaemia inhibitory factor (LIF) is released by endometrial secretory glands to stimulate adhesion of blastocyst to endometrial cells.
- Interleukin-11 (IL-11) is released from endometrial cells into uterine fluid and has a histamine action.
Explain oestrogen synthesis during pregnancy
