Endocrinology Of Pregnancy Flashcards
How far does sperm have to travel to get to the egg?
100000 times it’s length
How much semen do men have and how much of that is sperm?
15-120million spermatozoa per ml
They have 2-5 ml of semen at a time
1/100 spermatoazoa in ejaculate enter the cervix
1/10000 make it from the cervix to the ovum
Overall 1/million reach the egg
Where does the seminal fluid come from?
Mainly accessory sex glands: seminal vesicles, prostate, bulbourethral glands
Small contribution from epididymis and testes
What are the contents of the seminal fluid?
Fructose
Citric acid
Bicarbonate
Fibrinogen
Fibrinolytic enzymes
What is the capacitation of sperm?
Achieving fertilising capability in the female reproductive tract
Involves:
- Losing glycoprotein coat
- Change in surface membrane characteristics
- Development of whiplash movement of tail
It is oestrogen and calcium dependant
What is the acrosome reaction?
Sperm binding to the egg
Sperm binds to ZP3 (sperm receptor
Ca2+ influx into sperm (stimulated by progesterone
Release of Hyaluronidase and proteolytic enzymes from acrosome
This allows the spermatoazoa to penetrate the zona pellucida (glycoprotein) of the ovum
What is the process of fertilisation ?
Occurs within the Fallopian tube
Triggers a cortical reaction
Cortical granules release molecules which degrade the zona pellucida (ZP2 and 3)
This prevents further sperm binding as there are no receptors
The cells go from haploid to diploid
(The second polar body which is formed during oogenesis is also expulsed)
What happens during the development of conceptus?
The fertilised ovum continues to divide as it moved down Fallopian tube to uterus (3-4 days)
Received nutrients from uterine secretions
This free living phase can last for 9-10 days
What happens during implantation?
Attachment phase: outer trophoblast cells contact uterine surface epithelium
Decidualisation phase: changes in underlying uterine strongly tissue (within a few hours)
Requires progesterone domination in the presence of oestrogen
It is also promoted by molecules present such as LIF (leukaemia inhibitory factor) and IL11
What are the endometrial changes that occur during the decidualisation phase of implantation?
Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Growth of capillaries
Increased vascular permeability
This involves factors such as IL11, histamine, prostaglandins and TGF beta (which promotes angiogenesis)
What are the hormone changes during pregnancy?
hCG peaks during the first 10 weeks
After that there is a steady increase in levels of oestrogens, progesterone and human placental lactogen
(Human placental lactogen - made in placenta and modulates maternal metabolism to provide nutrients for foetus (not a clear role in lactation))
HCG acts in LH receptors
What is progesterone and oestrogen production like during pregnancy?
FIRST 40 DAYS:
Produced in corpus luteum (in maternal ovary) (stimulates by HCG which acts in LH receptors)
Essential for developing foetalplacental unit
This inhibits maternal LH and FSH
FROM DAY 40
Placenta starts to take over
(Makes oestrogen from DHEAS which can be made by both mother and foetus)
(Placenta makes progesterone from cholesterol)
What are the physiological changes in maternal hormones during pregnancy?
INCREASE
ACTH
Adrenal steroids
Prolactin
IGF 1 (stimulated by placental GH variant)
Iodothyronines (T3 and T4)
PTH related peptides
DECREASE
Gonadotrophins
Pituitary GH
TSH
What is the endocrine control of parturition?
(Labour)
Main hormone is oxytocin from posterior pituitary
This increases uterine contraction, cervical dilation and milk Ejection (prolactin synthesises milk)
There are also contributions from cortisol and oestrogen
What is the endocrine control of lactation?
Suckling stimulates neural pathways in the hypothalamus
This leads the ant pituitary to produce prolactin which stimulates milk synthesis
And the post pituitary to produce oxytocin which stimulates milk ejection
