Endocrinology Of Pregnancy Flashcards
(19 cards)
Voyage of Spermatoza
Travels x100,000 it’s length from testis to Fallopian tube
What does semen contain?
Spermatoza - 15-120million/ml
Seminal Fluid - 2-5ml
Leucocytes
Potential viruses (hep B/HIV)
Why so much Spermatoza required?
1/100 of Spermatoza in ejaculate enter the cervix
1/10,000 in cervix enters ovum
So overall 1/million reach the ovum
Seminal fluid from where?
Small contribution from epididymis/testis Mainly from accessory sex glands: -Seminal vesicles -Prostate -Bulbourethral glands
What is in seminal fluid?
Fructose Citric acid Bicarbonate Fibrinogen Fibrinolytic enzymes
Definition of Capacitation of Sperm
Achieve fertilising capability in the female reproductive tract
3 steps of capacitation
- Loss of glycoprotein ‘coat’
- Change in surface membrane characteristics
- Develop whiplash movements of tail
Other factors required for capacitation of sperm
Takes place in ionic and proteolytic environment of the Fallopian tube
Oestrogen-dependent
Ca2+ dependent
Acrosome reaction
Sperm binds to ZP3 (sperm receptor)
Ca2+ influx into sperm (stimulated by progesterone)
Release of hyaluronidase and proteolytic enzymes (from acrosome)
Sperm penetrates the Zona Pellucida (glycoprotein layer)
Fertilisation
Occurs within the Fallopian tube (widest part)
Triggers cortical reaction
Cortical granules release molecules which degrade Zona Pellucida (ZP2 & 3)
Therefore prevents further sperm binding as no receptors
Haploid -> Diploid
Development of Conceptus
Continues to divide as it moves down Fallopian tube to uterus (3-4days)
Receives nutrients from uterine secretions
Free-living phase can last for 9-10 days
Implantation
Attachment phase: outer trophoblast cells contact uterine surface epithelium
Then
Decidualisation phase: changes in underlying uterine stromal tissue (within a few hrs)
Requires progesterone domination in the presence of oestrogen
Attachment
Leukaemia inhibitory factor (LIF) from endometrial cells stimulates adhesion of blastocyst to endometrial cells
Interleukin-11 (IL11) also from endometrial cells is released into uterine fluid, and may be involved
Many other molecules involved in process (HB-EGF)
Decidualisation
Endometrial changes due to progesterone
- glandular epithelial secretion
- glycogen accumulation in stromal cell cytoplasm
- growth of capillaries
- increased vascular permeability (odema)
Factors involved:
Interleukin-11 (IL11), histamine, certain prostaglandins + TGFbeta (promotes angiogenesis)
Hormone Changes during Pregnancy
hCG - peaks to about 75% plasma concentration during 9 weeks then decreases
Human placental Lactotrophs and oestrogens increase gradually to about 50% plasma concentration until 40 weeks then drops at birth
Progesterone increases more steeply until about 35 weeks to 100% plasma concentration then drops then on
Progesterone & Oestrogen Production during Pregnancy
First 40 days:
Produced in corpus luteum (in 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 starts to take over
Physiological Changes in Maternal Hormones
Increase: ACTH Adrenal Steroids Prolactin IGF1 (stimulated by placental GH -variant) Iodothyronines PTH related peptides
Decrease:
Gonadotrophins
Pituitary GH
TSH
Endocrine Control of Partruition
Oxytocin with the help of Oestrogen and Progesterone stimulates uterine contraction, cervical dilatation and male ejection
Oxytocin made by posterior pituitary
Endocrine control of Lactation
Suckling stimulates neural pathways to the hypothalamus and in turn to the pituitary which:
- stimulates oxytocin release from neurohypophysis (milk ejection)
- stimulates prolactin release from adenohypophysis (milk synthesis)
