Endo 11 - Endocrinology of Pregnancy Flashcards
The seminal vesicles are located behind which organ
The prostate
What do Leydig cells make?
Testosterone
In M, where is oestrogen made and give 2 uses for it
Made from the conversion of testosterone to oestrogen via aromatase.
- Needed for tubular fluid reabsorption for semen concentration
- Needed for bone growth - signals closure of the growth plates (epiphyses)
What induces secretion of nutrients and glycoprotein into the epididymal fluid?
Why are glycoproteins and nutrients secreted into the epididymal fluid?
Androgens
Needed to provide energy for impending journey (sperm) and to coat the surface of spermatozoa
What are the constituents of sperm?
- Spermatozoa - 15-120 million/ml
- Seminal fluid - 2-5ml
- Leukocytes
- Potential viruses (e.g. HIV / Hep B)
Only 1/million reach ovum
Seminal fluid comes mainly from the accessory sex glands, which are
- Seminal vesicles
- Prostate
- Bulbourethral glands
(small contribution from epididymis and testis)
What is capacitation of sperm?
Where does capacitation occur?
It is the way in which sperm achieve fertilising capability in the female reproductive tract. 3 things happen:
- Loss of glycoprotein coat
- Change in surface membrane characteristics
- Develop whiplash movements of tail
Capacitation occurs in ionic and proteolytic environment of the Fallopian tube
Capacitation of sperm is dependent on which 2 things?
- Oestrogen
2. Ca
Describe the acrosome reaction
- Capacitated sperm - binds to ZP3 receptor on ovum
- Ca influx into sperm (stimulated by progesterone)
- Causes acrosome to release hyaluronidase and proteolytic enzymes —-> enables spermatozoon to penetrate the zona pellucida
Zona pellucida = glycoprotein layer that surrounds the oocytes plasma membrane
If fertilisation does not occur in the Fallopian tube, what is it called
Ectopic pregnancy
Where does fertilisation occur?
In the fallopian tube
What reaction does fertilisation trigger
Cortical reaction
Cortical granules release molecules which degrade bona pellucida (e.g. ZP2 and 3) - prevents further sperm binding as no receptors
Haploid —> Diploid
How does fertilisation cause expulsion of the 2nd polar body?
In oogenesis meiosis, chromosomes evenly divided between daughter cells, but the cytoplasm is divided unevenly.
The ovum retains the cytoplasm, whilst the other cell degenerates as it has no cytoplasm
Explain the development of the conceptus
Fertilized egg continues to divide as it moves down Fallopian tube.
Conceptus receives nutrients from uterine secretions - this free-living phase lasts for 9-10 days
Conceptus compacts to form a 8-16 cell morula - which then becomes a blastocyst
Describe the cellular arrangements in a blastocyst
Inner cell mass will become the embryo
Trophoblast cells will form the chorion/placenta
Transfer of the conceptus/blastocyst to the uterus is facilitated by?
An increasing progesterone:oestrogen ratio - luteal phase
Describe the 2 phases of implantation
- Attachment phase - outer trophoblast cells contact uterine surface epithelium
- Decidualisation phase - changes in underlying uterine stroll tissue (within few hours) - requires progesterone domination in the presence of oestrogen (progesterone promotes gestation)
Which 2 factors in the attachment phase stimulates adhesion of the blastocyst to endometrial cells?
- Leukaemia inhibitory factor (LIF) - from endometrial secretory glands
- IL-11
in the decidualisation phase of implantation, endometrial changes occur due to progesterone. These changes include?
What factors are involved?
Endometrial changes:
- Glandular epithelial secretion
- Glycogen accumulation in stroll cell cytoplasm
- Growth capillaries
- Increased vascular permeability (causing oedema)
Factors involved:
IL-11, histamine, certain prostaglandins and TGF-B
TGF-B promotes what
Angiogenesis
hCG is produced where?
Placenta (by trophoblasts)
2 ways to check if an egg is present?
- Ultrasound
2. Day 21 progesterone should be high
In the first 40 days, where is progesterone and oestrogen produced and what stimulates it?
Corpus luteum, stimulated by hCG which acts on LH receptors
hCG acts on LH receptors
LH and FSH inhibited (-ve feedback)
In the first 40 days, why is progesterone and oestrogen production vital?
Important for developing fetoplacental unit
From day 40, how is progesterone and oestrogen produced?
Placenta starts to take over
In a pregnancy test, what should be measured?
Foetal hCG levels (takes 2 weeks after conception)
If you want to test earlier, check plasma hCG levels
Describe placenta-independent progesterone and oestrogen production
Mother and foetus both produce DHEAS —> converted through the placenta into oestradiol
What hormones may increase during pregnancy?
- ACTH
- Adrenal steroids
- Prolactin - if you wanna detect prolactinoma in pregnancy, use MRI and visual fields
- IGF1 - stimulated by placental GH-variant
- Iodothyronines - hCG shares an alpha subunit with TSH
- PTH related peptides
What hormones may decrease during pregnancy?
- Gonadotrophins
- Pituitary GH
- TSH
Parturition occurs because a rise in Ca causes uterine contraction. How does this happen
- Oestrogen and oxytocin drive this (progesterone inhibits)
- Oestrogen rises constantly in pregnancy –> increases effect of oxytocin by increasing the number of oxytocin receptors on muscles
Explain endocrine control of lactation
- Suckling - stimulates neural pathways to hypothalamus
- This stimulates APG (prolactin) and PPG (oxytocin).
- Prolactin = milk synthesis
Oxytocin = milk ejection (as well as cervical dilatation and uterine contraction)
How can marathon runners get hypogonadotrophich hypogonadism
Nipple stimulation when running –> increased prolactin —> GnRH suppressed
