Endocrinology of Pregnancy Flashcards
In the male RT, what is under E control?
Tubular fluid reabsorption
In:
x rete testis
x epididymis
In the male RT, what is under ANDROGEN control?
Why is it important?
Nutrient & glycoprotein secretion into:
x epididymal fluid
Important as:
o provides energy for journey
o coats the surface of the spermatozoa
What can LOW aromatase lead in males?
Convertes testosterone to E = LOW E
o TALL as difficile plate closure needs E
o Osteoporosis
What is released during ejaculation?
Semen
What does semen consist of?
- Spermatozoa (15-120million/ml)
- Seminal fluid (2-5ml)
- Leucocytes
(so potential viruses e.g. hepB, HIV)
Where does the semen go when ejaculated?
Into the VAGINA or CERVICAL CANAL
1/100 = enter cervix 1/10,000 = cervix to ovum 1/million = ovum
What contributes to the seminal fluid?
SMALL contribution from:
o epididymis/testis
MAJOR contribution from:
o Accessory sex glands
What makes up the accessory sex glands?
o Seminal vesicles (produce fructose & fibrinogen)
o Prostate (produce citric acid)
o Bulbourethral glands
What is meant by ‘Capacitation of Sperm’?
o In the SEMINIFEROUS TUBULE the spermatozoa are incapable of fertilisation
o In the VAS DEFERENS they are
- capable of movement
BUT
- have little capability of fertilisation
HENCE for full fertilisation activity, needs to undergo capacitation in the OVIDUCT (female repro tract)
Where does Capacitation occur?
OVIDUCT/fallopian tube
i.e. female repro tract
Steps of Capacitation?
- Loss of GLYCOPROTEIN ‘coat’
- Change in SM characteristics
- Develop WHIPLASH movements of tail
Envrionment needed for Capacitation?
o Ionic & proteolytic envrionment in fallopian tube
o Oestrogen-dependent
o Ca2+-dependent
What does the acrosome reaction allow for the capacitated spermatozoa to do?
- BIND to
AND - PENETRATE the zona pellucida
via. the release of hyaluronidase & proteolytic enzymes
Describe the acrosome reaction
Location: Fallopian tubes
Result: expulsion of 2nd polar body from ovum
- Sperm binds to the ZP3 (sperm receptor - via. G-protein mediation)
- Ca2+ influx into the sperm (mediated via. PG)
- Penetrates the zona pellucida (via. hyaluronidase released by acrosome)
What prevents further sperm binding?
Cortical reaction!
Cortical granules release molecules which degrade zona pellucida (+ ZP2/3)
HENCE prevents further sperm binding as NO receptors
Conceptus?
Fertilised ovum
How does the Conceptus develop?
- Continues to divide as it moves DOWN the fallopian tube –> uterus (3-4days)
o recieves nutrients from uterine secretions
o free-living phase can last for 9-10days - Conceptus then compacts to an 8-16 cell MORULA
- Then a BLASTOCYST - 2 seperate cell populations
o Inner mass = becomes embryo
o Outer trophoblast = chorion - Then reaches the uterus facilitated by INCREASED PG:E (luteal phase)
What hormone is released when fertilisation takes place?
hCG - from the placenta
2 stages of Implantation?
- Attachment Phase
o OUTER trophoblast cells contact uterine surface epithelium - Decidualisation Phase
o changes in underlying uterine stromal tissue (within a few houes)
What is required for implantation to take place in terms of hormones?
PG domination in the presence of E
What is required for implantation to take place in terms of molecules?
LIF (leukaemia inhibitory factor)
o released from endometrial secetory glands (and ?blastocyst)
o stimulates ADHESION of blastocyst to endometrium
IL-11
o released into uterine fluid from endometrial cells
Explain the Decidualisation Stage
Endometrial changes due to PG!
o Glandular epithelial secretion
o Glycogen accumulation in stromal cell cytoplasm (localised changes in IC composition)
o Growth of capillaries
o Increased vascular permeability (oedema!)
What factors are invovled in the Decidualisation Stage?
IL-11
Histamine
Prostaglandins
TGF-beta (promotes angiogenesis)
Describe the hormone changes in the first 5-6 weeks?
o Maternal ovaries release gonadal steroids
o Circulating [PG] & [oestradiol] are HIGH and rising
- INHIBIT the release of LH & FSH
- the STIMULATORY role on corpus luteum is hence taken over by hCG
