Endocrinology of pregnancy Flashcards
Male reproductive tract (efferent ducts) - What induces tubular fluid reabsorption
Oestrogen - concentrates the sperm
What happens in the epididymis?
Nutrient and glycoprotein secretion into epididymal fluid (induced by androgens)
How many sperm reach the ovum?
Overall 1/million reach the sperm
In semen how many spermatozoa are there in how much seminal fluid?
15-120 million/ml
2-5ml
What is the seminal fluid made from?
Small contribution from - epididymis
Mainly from accessory sex glands - Seminal vesicles, prostate and bulbourethral glands; contribute fructose, fibrinogen and citric acid etc
Define capacitation of sperm?
Achieve fertilising capability in the female reproductive tract
This occurs in ionic and proteolytic environments of the Fallopian tube and is oestrogen and Ca2+ dependent.
How does capacitation occur?
1) Loss of glycoprotein coat
2) Change in surface membrane characteristics
3) Develop whiplash movement of tail
What does the capacitated sperm have at the head?
Acrosome
What does the acrosome bind to and what does it cause?
Acrosome reaction
ZP3 glyocprotein (sperm receptor) in the Zona Pellucida (glycoprotein layer). This causes Ca2+ influx into the sperm --> release of hyaluronidase and proteolytic enzymes from the acrosome. This allows for the penetration of the zona pellucida.
Describe fertilisation?
Occurs within the fallopian tube which triggers cortical reaction.
Cortical granules release molecules which degrade the zona pellcuida, preventing furthter sperm binding (no receptors)
Haploid –> Diploid
What is the conceptus?
What is formed directly after the fusion of the sperm and the egg
How does the conceptus develop?
Divides as it moves down the fallopian tube to uterus (3-4 days)
Receives nutrients from uterine secretions
This free-living phase can last for 9-10 days
Draw the development of the cenceptus?
Fertilized egg –> 2 cell conceptus –> 4 cell C –> 8 cell C –> morula–> blastocyst
See diagram
Draw and label a blastocyst
See diagram
Inner cell mass - embryo
Trophoblast cells - chorion (placenta)
What are the two stages of implantation?
Attachment phase
Decidualisation phase
This requires porgesterone dominance in the presence of oestrogen.
Leukemia Inhibitiory factor (LIF) and IL11 are key factors required for this to occur
Define attachment phase
Outer trophoblast cells contact uterine surface epithelium
Define decidualisation phase
Changes in the underlying uterine stromal tissue (within a few hours)
Describe LIF?
Secreted from endometrial secretory glands - stimulates adhesion of blastocyst to endometrial cells
Describe IL11?
Secreted from endometrial cells is released into uterine fluid, and may be involved with attachment.
During decidualisation what endometrial changes occur due to progesterone?
Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Growth of capillaries
Increased vascular permeability (–> oedema)
What factors are involved in dicidualisation?
IL-11, histamine, certain prostaglandins & TGFb(promotes angiogenesis)
Where is hCG produced?
Human Chorionic Gonadotrophin hormone produced in the placenta
Draw the graph showing the changes in the hormones during pregnancy
See diagram
Describe the progesterone and oestrogen production during pregnancy?
First 40 days - produced by the corpus luteum (in the maternal ovary). Stimulated by hCG (produced by trophoblasts) which acts on LH receptors
Essential for developing fetoplacental unit
Inhibits maternal LH & FSH (-ve feedback)
From day 40 - placenta takes over
How can you check if an egg has been produced?
Look via ultrasound for a corpus luteum
Look for rising levels of progesterone typically at day 21
Draw the mother-fetus-placenta axis
See diagram - key thing to take away from this is that mother and fetus produce DHEAS. DHEAS acts on the placenta to produce oestradiol.
Describe the increase in physiological changes in maternal hormones during pregnancy?
Increase in:
ACTH
Adrenal steroids
Prolactin - can’t track prolactinoma during pregnancy cause its naturally raised. Check visual fields
IGF-1 (stimulated by placental GH-variant)
Iodothyronines - supports the body. hCG is linked to this.
PTH related peptides - involved in Ca2+ during pregnancy.
Describe the decrease in physiological changes in maternal hormones during pregnancy?
Gonadotrophins - due to the high circulating oestrogen levels - negative feedback
Pituitary GH
TSH - hCG works to drive the thyroid so you don’t need to much TSH. Share a receptor
Draw the parturition diagram
Complex process - Maybe don’t need to know…
Main point - Oxytocin binds to the oxytocin receptor which increases during pregnancy leading to endometrial contraction. There are also influences from oestrogen and cortisol.
Where is oxytocin produced?
In the neurohypophysis
Describe lactation
Suckling (stimulus) –> neural pathway to the hypothalamus –> pituitary
Neurohypophysis –> oxytocin –> ejection of the milk
Adenohypophysis –> prolactin –> synthesis of the milk
