Endocrinology of pregnancy Flashcards
What hormone induces tubular fluid reabsorption?
Oestrogen.
What hormones induce nutrients and glycoprotein secretion into epididymal fluid?
Androgens.
What distance does the spermatozoa travel from testis to oviduct?
100,000x its length, equivalent to 150km for a 1.5m human.
What is the spermatozoa concentration in semen?
15-120 million/ml
What is the volume of seminal fluid in semen?
2-5ml
What are the contents of semen?
Spermatozoa
Seminal fluid
Leucocytes
Potentially viruses, e.g. hepatitis B, HIV
What proportion of spermatozoa in ejaculate enter the cervix?
1%
What proportion of spermatozoa that entered the cervix reach the ovum?
0.01%
What proportion of spermatozoa in ejaculate reach the ovum?
1 in a million.
Where is seminal fluid produced?
Small contribution from epididymis/testis.
Mainly from accessory sex glands: seminal vesicles, prostate, bulbourethral glands.
What is capacitation of sperm?
Achieve fertilising capacity in the female reproductive tract.
Loss of glycoprotein coat.
Change in surface membrane characteristics.
Develop whiplash movements of tail.
Takes place in ionic and proteolytic environment of Fallopian tube.
Oestrogen-dependent.
Calcium-dependent.
What is the acrosome reaction?
Capacitated sperm binds to ZP3 (glycoprotein receptor).
Calcium influx into sperm (stimulated by progesterone).
Release of hyaluronidase and proteolytic enzymes.
Spermatozoon penetrates the zona pellucida (glycoprotein coat of ovum).
Where does fertilisation occur?
Fallopian tube
What reaction does fertilisation trigger?
Cortical reaction.
What is the cortical reaction after fertilisation?
Cortical granules release molecules which degrade zona pellucida (e.g. ZP2 and 3), therefore prevents further sperm binding.
Describe the development of the conceptus immediately after fertilisation.
Continues to divide as it moves down Fallopian tube to uterus (3-4 days).
Receives nutrients from uterine secretions.
This free-living phase (unattached) can last for 9-10 days.
Fertilised egg - 2-cell conceptus - 4-cell conceptus - 8-cell conceptus - compaction - morula - blastocyst
What does the inner cell mass of the blastocyst go on to form?
Embryo.
What do the trophoblast cells of the blastocyst go on to form?
Placenta.
What are the phases of embryonic implantation?
Attachment phase- outer trophoblast cells contact uterine surface epithelium.
Decidualisation phase- changes in underlying uterine stroll tissue (within a few hours).
Requires progesterone domination in the presence of oestrogen. (PROgesterone PROmotes gestation)
What is the role of LIF (leukaemia inhibitory factor) and IL11 in embryonic implantation?
Promote trophoblast migration and decidualisation and attachment phases in the presence of progesterone.
What is the role of LIF (leukaemia inhibitory factor) in the attachment phase of embryonic implantation?
Stimulates adhesion of blastocyst to endometrial cells, produced from secretory glands (&blastocyst?).
What molecules are involved in the attachment phase of embryonic implantation?
Leukaemia inhibitory factor (LIF)- from endometrial secretory glands (&blastocyst?), stimulates adhesion of blastocyst to endometrial cells.
Interleukin-11 (IL11)- also from endometrial cells, released into uterine fluid and may be involved.
Many other molecules involved in process, e.g. HB-EGF.
What endometrial changes due to progesterone are seen in the decidualisation phase of embryonic implantation?
Glandular epithelial secretion.
Glycogen accumulation in stroll cell cytoplasm.
Growth of capillaries.
Increased vascular permeability (leading to oedema).
What factors are involved in the decidualisation phase of embryonic implantation?
Interleukin-11 (IL11)
Histamine
Certain prostaglandins
TGF-beta (promotes angiogenesis)
Where is HCG (human chorionic gonadotrophin) produced during pregnancy?
Placenta.
In the first 40 days of pregnancy, where are progesterone and oestrogen produced?
Corpus luteum (in maternal ovary).
What stimulates production of progesterone and oestrogen in the first 40 days of pregnancy?
HCG (produced by trophoblasts), acts on LH receptors.
What is the importance of progesterone and oestrogen in the first 40 days of pregnancy?
Essential for developing fetoplacental unit.
Inhibit maternal LH and FSH (negative feedback).
Where are progesterone and oestrogen produced after the first 40 days of pregnancy?
Placenta starts to take over from corpus luteum.
What does the placenta convert maternal and foetal DHEAS into?
Oestradiol, oestriol, oestrone, all by conjugation.
Which maternal hormones may increase in concentration in pregnancy?
ACTH
Adrenal steroids
Prolactin
IGF-1 (stimulated by placental GH variant)
Iodothyronines
PTH related peptides
Which maternal hormones may decrease in concentration in pregnancy?
Gonadotrophins
Pituitary GH
TSH
What tests may be performed to assess whether a woman is ovulating?
Day 21 progesterone- must come from corpus luteum, proving ovulation if progesterone is high.
Ultrasound to look for corpus luteum.
What is the role of calcium in parturition?
Controls muscle action.
Increase in calcium causes contraction of uterus.
Driven by oestrogen, inhibited by progesterone.
What is the role of oxytocin in parturition?
Causes contraction of uterus by acting on oxytocin receptors.
Bonding chemical- feel good, trust.
Describe the endocrine control of lactation.
Suckling (stimulus)
Neural pathways to hypothalamus and then pituitary.
Neurohypophysis produces oxytocin which stimulates milk ejection.
Adenohypophysis produces prolactin which stimulates milk synthesis.
List LIF stimulators.
TGF
TNF
HB-EGF
IL1
Leptin
Progesterone
List IL11 stimulators.
IL1
TNF
TGF
Relaxin
PGE2
