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Endocrinology > 11. Endocrinology of pregnancy > Flashcards

11. Endocrinology of pregnancy Flashcards

1
Q

Which cells make spermatozoa?

A

Sertoli cells

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2
Q

Which cells make testosterone?

A

Leydig cells

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3
Q

What is oestrogen required for in men and what can aromatase deficiency lead to?

A
  • Tubular fluid reabsorption
  • Bones
  • Therefore, aromatase deficiency can lead to infertility, osteoporosis and being tall
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4
Q

What can aromatase deficiency lead to in females?

A

Virilisation
• Hirsutism
• Deepening voice
• Amenorrhoea

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5
Q

Where is most tubular fluid reabsorbed?

A
  • Within the rete testis and early epididymis

* Under oestrogen (produced by sertoli cells)

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6
Q

What are secretory products, how are they induced and what do they do?

A
  • Products e.g. fructose + glycoproteins, vital for the maturation process
  • Induced by androgens
  • Secreted into epididymal fluid
  • Provide energy
  • Coat the spermatozoa - protection
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7
Q

What proportion of spermatozoa reach the ovum?

A

< 1/10^6

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8
Q

What does semen consist of?

A
  • Spermatozoa (15-120million/ml)
  • Seminal fluid (2-5ml)
  • Leucocytes
  • Potentially viruses
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9
Q

What proportion of spermatozoa enter the cervix and the ovum?

A

• 1/100 enter the cervix
• 1/10,000 from cervix to ovum, so:
- 1/1 million reach the ovum

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10
Q

Where (and how) is seminal fluid produced?

A

Accessory sex glands
• Seminal vesicles
• Prostate
• Bulbourethral glands

  • Concentrated using androgens
  • Given nutrients and glycoproteins using oestrogens
  • Small contribution from epididymis and testes
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11
Q

How does function of the spermatozoa compare in the seminiferous tubule and vas deferens?

A
  • Seminiferous tubule - quiescent and incapable of fertilising an ovum
  • Vas deferens - limited movement, limited capability for fertilising ovum
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12
Q

When/where do spermatozoa reach full activity?

A

• Once within the female reproductive tract
- ionic + proteolytic environment of the fallopian tube
• Capacitation:
- lose glycoprotein coat
- change in surface membrane characteristics
- develop whiplash movements of tail
• Oestrogen-dependent
• Ca2+ dependent

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13
Q

How does the movement of sperm in the female reproductive tract compare to the male?

A
  • Male - muscle contractions

* Female - mobilise themselves

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14
Q

What is the acrosome reaction?

A

• Sperm acrosome binds to ZP3 (glycoprotein receptor)
• Ca2+ influx into sperm (stimulated by progesterone)
• Release of hyaluronidase (breaks down polysaccharides + proteolytic enzymes)
• Spermatozoon can penetrate the Zona pellucida oocyte and get straight to the egg
- cortical reaction - cortical granules release molecules to degrade Zona pellucida, blocking more sperm binding

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15
Q

What is the Zona pellucida?

A

Glycoprotein membrane surrounding the plasma membrane of the oocyte

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16
Q

What happens to the polar bodies in fertilisation?

A
  • Expulsion of second polar body (haploid)
  • Chromosome are evenly divided between the resultant 2 cells
  • Cytoplasma is divided unevenly - ovum retains cytoplasm and last polar body degenerates
17
Q

How long does it take for the fertilised egg to move from the Fallopian tube to the uterus, and where does it receive nutrients from?

A
  • 3-4 days
  • Nutrients from uterine secretions
  • Can remain in the free-living phase for 9-10 days
  • Inner cells receive less and less nutrients
  • Occurs in the luteal phase - oestrogen and progesterone are high
18
Q

What is compaction?

A

• 8-cell conceptus compacts to form an 8-16 cell morula

19
Q

What does a blastocyst comprise?

A
  • Inner cell mass, which becomes the embryo

* Outer trophoblast cells, which become the chorion then the placenta

20
Q

What change in the hormones facilitates transfer of the blastocyst to the uterus?

A

Increasing the progesterone:oestrogen ratio (luteal phase) (progesterone domination in the presence of oestrogen)

21
Q

What are the 2 phases of implantation?

A

• Attachment phase - outer trophoblast cells make contact with the uterine surface epithelium - establishing a system to get nutrients
• Decidualisation phase
- changes of the underlying uterine stromal tissue
- glandular epithelial secretion
- growth of capillaries
- decidua lines the uterus during pregnancy
- IL-11 involved

22
Q

Which 2 molecules are important in the attachment phase and why?

A

• Leukaemia inhibitory factor (LIF)
- from endometrial secretory glands (and blastocyst?)
- Stimulates adhesion to endometrial cells
• Interleukin-11
- also released from endometrial cells
- released into uterine fluid

23
Q

Give some examples of LIF and IL-11 stimulators

A
  • LIF stimulators - TGF, TNF, leptin, progesterone

* IL-11 stimulators - IL1, TNF, TGF, PGE2

24
Q

Which hormone suddenly surges during pregnancy and why is this significant?

A
  • hCG (produced by trophoblasts)
  • Initially takes over the role of LH - acts on LH receptors
  • Produced in the placenta
  • Can be measured in a urine pregnancy test 2 weeks after conception (earlier in a blood test)

(oestrogen, progesterone and human placental lactogen also increase)

25
Q

Summarise progesterone and oestrogen production in the first 40 days of pregnancy

A

• Produced in the corpus luteum
• Stimulated by hCG acting on LH receptors
• Essential for developing fetoplacental unit
• Oestrogen inhibits maternal LH + FSH (negative feedback)
- hCG overrides this

26
Q

What is DHEAS?

A
  • Dehydroepiandrosterone sulfate
  • Androgen
  • Precursor made by maternal and foetal adrenals
27
Q

What happens to oestrogen and progesterone production from day 40

A

• Placenta starts to take over oestrogen and progesterone production
• Not driven by LH/FSH/hCG
• Mother and foetus produce DHEAS and progesterone
• DHEAS is taken up by the placenta
- produces oestradiol and small amounts of oestrone
• mother provides the precursors e.g. pregnenolone => progesterone then leads to steroid production by the foetus (in foetal adrenals)

28
Q

Why can’t a change in oestradiol levels necessarily tell you that the foetus is in distress?

A

Mother produces oestradiol as well as the foetus

29
Q

What is the main oestrogen of pregnancy

A

Oestriol (one of the metabolic products of oestradiol)

30
Q

How is oestriol different to oestradiol?

A
  • Source of oestriol is foetal
  • It is weaker than oestradiol
  • Produced in large amounts during pregnancy
31
Q

How is oestriol formed?

A
  • Conjugation of DHEA in the foetal liver to form 16a-hydroxy DHEAS
  • Goes to the placenta which deconjugates it and uses it to form oestriol
32
Q

When should you be worried about the foetus when looking at the oestrogen levels?

A

Ratio of oestriol:oestradiol and oestrone or the ratio of oestriol:total oestrogens changes

33
Q

How can you assess whether a woman is ovulating?

A
  • Normally happens midway through the cycle (day 14)
  • Day 21 progesterone test - progesterone can only come from the corpus luteum
  • Ultrasound test
34
Q

What is parturition and how is it controlled by hormones?

A

• Giving birth

• Involves contraction of actin and myosin filaments
- needs increased intracellular [Ca] (driven partly by oestrogen and inhibited by progesterone)
• Oestrogen stimulates production of prostaglandins by the endometrial cells
• Prostaglandins stimulate the production and release of Ca into the cytoplasm from intracellular stores
• Oestrogen also stimulates oestrogen receptors on endometrial cells
• Therefore, increased chance of contraction

  • Progesterones inhibits prostaglandin synthesis and inhibits oestrogen receptors
  • Useful for control (but doesn’t dominate)
  • Oxytocin receptors on muscles - oxytocin causes contraction (oestrogen and cortisol needed, and progesterone:oestrogen ration needs to change too)
  • Opens Ca channels allowing Ca to move in from outside
35
Q

What determines the change of production of steroids from progesterone to oestrogen?

A

When the foetus reaches a certain size

36
Q

Which 2 hormone are involved in breast-feeding and what do they do?

A
  • Prolactin - promotes milk synthesis

* Oxytocin - promotes milk ejection

37
Q

How does suckling promote hormone production in breast-feeding?

A
  • Neural pathways of nipple stimulation go to the hypothalamus and pituitary gland
  • Pituitary gland makes more prolactin (adenohypophysis) and oxytocin (neurohypophysis)
  • This completes its neuroendocrine relfex arc
38
Q

What is the difference between hypogonadotropic and hypogonadism?

A
  • Hypogonadotropic - low LH/FSH

* Hypogonadism - low testosterone/oestrogen

Endocrinology (17 decks)

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