Endocrinology of pregnancy

Question 1

In relation to the size of a sperm cell, how long is the journey of a sperm from testes to oviduct?

Answer 1

100,000 times the length of a sperm (<1/10^6 make it)

Question 2

What happens to most of the tubular fluid in men?

Answer 2

It reabsorbed within the rate testis and early epididymis under the control of oestrogen

Question 3

What produces tubular fluid?

Answer 3

Sertoli cells

Question 4

What controls secretion of nutrients and other molecules into the epididymal fluid?

Answer 4

Androgens

Question 5

What are the nutrients and other molecules for?

Answer 5

Provide journey for impending journey and coat the surface of the spermatozoon

Question 6

Where does a vasectomy occur?

Answer 6

Vas deferens at the bottom end

Question 7

How does concentration of spermatozoa compare in vas deferens compared to later on?

Answer 7

It is much higher at the vas deferens as lots of fluid is added along the way

Question 8

What does semen consist of?

Answer 8

Spermatozoa
Seminal fluid
Leucocytes
Viruses (potentially)

Question 9

Seminal fluid from

Answer 9

Mainly from seminal vesicles, prostrate, bulbourethral glands

small contribution from::
-epididymis/testis

Question 10

What are spermatozoa in the seminiferous tubule like?

Answer 10

Quiescent and incapable of fertilising an ovum

Question 11

What are spermatozoa in the vas deferens like?

Answer 11

Capable of limited movement (whiplash)

Limited ability to fertilise

Question 12

When is full activity and fertilising capability achieved?

Answer 12

When in the female reproductive tract

Question 13

What is the process of reaching full activity and fertilising capability called?

Answer 13

Capacitation

Question 14

What percentage of spermatozoa in ejaculate make it to the cervix?

Answer 14

1%

Question 15

How do the spermatozoa achieve capacitation? (3 things)

Answer 15

Loss of glycoprotein coat
Change in surface membrane characteristics
Whiplash movements of the tail

Question 16

Why can the spermatozoa lose the glycoprotein coat?

Answer 16

It has a protective function in the vagina but once in the uterus it isn’t necessary

Question 17

Where does capacitation occur

What two things are all the components of capacitation reliable on?

Answer 17

In ionic and proteolytic environment of fallopian tubes

Oestrogen and calcium

Question 18

What happens to a sperm as it approaches an ovum?

Answer 18

There are changes in the membrane

Question 19

What does a spermatozoon bind to?

Answer 19

ZP3 glycoprotein on zona pellucida

Question 20

What happens after the spermatozoon binds to ZP3?

Answer 20

Progesterone stimulates the calcium influx into the spermatozoon

Question 21

What does the calcium influx lead to in fertilisation?

Answer 21

Calcium dependent acrosome reaction

Question 22

What does the calcium dependent acrosome reaction enable?

Answer 22

An exposed spermatozoon recognition site to bind to a second glycoprotein (ZP2)

Question 23

What happens once ZP2 has bound?

Answer 23

The acrosome releases its enzymes allowing penetration of the zona pellucida so that the head of the spermatozoon can enter the ovum

Question 24

Where does fertilisation normally occur?

Answer 24

Fallopian tubes

Question 25

What does fertilisation lead to?

Answer 25

Expulsion of the second polar body and the zonal reaction

Question 26

What is the zonal reaction?

Answer 26

Cortical granules release molecules which degrade the zona pellucida, this prevents further binding of other sperm. This is also calcium dependent

Question 27

What is the conceptus?

Answer 27

The product of the zygote starting to divide (baby early days)

Question 28

What happens to the conceptus as it moves from fallopian tubes to uterus?

Answer 28

It continues to divide

Question 29

How long does it take for the conceptus to travel from fallopian tubes to the uterus?

Answer 29

3-4 days

Question 30

How does the developing conceptus receive its nutrients until implantation?

Answer 30

Uterine secretions

Question 31

How long does the free living phase last (between formation and implantation)?

Answer 31

9-10 days

Question 32

While this occurs, the woman is in her luteal phase, what does this mean?

Answer 32

There will be high oestrogen and progesterone

Question 33

What does the conceptus first compact to form?

Answer 33

8-16 cell morula

Question 34

What does the 8-16 cell morula then become?

Answer 34

A blastocyst

Question 35

What are the two parts of the blastocyst and what do they become?

Answer 35

An inner cell mass- becomes the embryo | Trophectoderm- becomes the chorion which becomes the placenta

Question 36

What facilitates the transfer to the uterus?

Answer 36

Increasing progesterone:oestrogen ratio due to the luteal phase

Question 37

What is the reason for implantation?

Answer 37

Establishing a system for getting nutrients form the mother to all cells in the embryo

Question 38

What does the initial attachment phase consist of?

Answer 38

Outer trophoblast cells making contact with the uterine surface epithelium

Question 39

What is the decidua?

Answer 39

Thick layer of modified mucous membrane which lines the uterus during pregnancy and is shed with afterbirth

Question 40

When does decidualisation of the underlying stromal tissue occur?

Answer 40

Within a few hours of implantation

Question 41

Which two molecules are of particular importance in attachment?

Answer 41

``` Leukaemia inhibitory factor (LIF) Interleukin 11 (IL-11) ```

Question 42

Where does leukaemia inhibitory factor come from?

Answer 42

Endometrial secretory glands

Question 43

What does leukaemia inhibitory factor do?

Answer 43

Stimulation adhesion of the blastocyst to the endometrial cells

Question 44

Where does interleukin-11 come from?

Answer 44

Endometrial cells

Question 45

What is interleukin-11 released into?

Answer 45

Uterine fluid

Question 46

What is the decidualisation reaction?

Answer 46

Invasion of the underlying uterine stromal tissue by the trophoblast cells of the blastocyst

Question 47

What happens within hours due to the decidualisation reaction?

Answer 47

Increased vascular permeability in the invasion region | Localised changes in intracellular composition and progressive sprouting and growth of capillaries

Question 48

What factors are involved in the decidualisation reaction?

Answer 48

Mainly IL-11 Histamine Certain prostaglandins TGFbeta- promotes angiogenesis

Question 49

When does hCG reach a peak?

Answer 49

8 weeks

Question 50

When is hCG vital and why?

Answer 50

First 6 weeks as its job is to replace LH

Question 51

What happens in terms of hormones that leads to menstruation?

Answer 51

Levels of oestrogen and progesterone fall

Question 52

Why is hCG released during pregnancy?

Answer 52

It is needed to maintain the stimulation of oestrogen and progesterone

Question 53

What produces hCG?

Answer 53

Trophoblast cells

Question 54

How does hCG work?

Answer 54

It can bind to LH receptors on corpus luteum hence replacing the effects of LH

Question 55

Why are the ovaries no longer necessary in a pregnancy after 5 weeks?

Answer 55

The placenta will have taken over production of the hormones

Question 56

What happens to oestrogen and progesterone levels throughout pregnancy?

Answer 56

They increase and until the end, progesterone remains the dominant influence

Question 57

What is human placental lactogen?

Answer 57

It is produced by the placenta Growth hormone Prolactin like effects

Question 58

What are the three components important in providing steroids?

Answer 58

Mother Foetus Placenta

Question 59

What does the mother provide in terms of steroids?

Answer 59

The precursors

Question 60

What is the most common precursor?

Answer 60

Pregnenolone which leads to progesterone

Question 61

What causes steroid production in the foetus?

Answer 61

Progesterone

Question 62

What precursor does the foetal and maternal adrenals produce?

Answer 62

Dehydroepiandrosterone sulfate (DHEAS)

Question 63

What is DHEAS taken up by the placenta to produce?

Answer 63

Oestradiol and small amounts of oestrone

Question 64

What is the main oestrogen of pregnancy?

Answer 64

Oestriol

Question 65

If you wanted to look at the health of the baby, which oestrogen would you look at?

Answer 65

Oestriol because its source is completely foetal

Question 66

How is oestriol formed?

Answer 66

It comes from the conjugation of DHEAS in the foetal liver to form 16alpha-hydroxy DHEAS which then goes to the placenta which deconjugates it and uses it to form estriol

Question 67

What happens to most maternal hormones during pregnancy?

Answer 67

They increase

Question 68

What happens to the pituitary during pregnancy?

Answer 68

It enlarges

Question 69

What is responsible for the action of parturition?

Answer 69

Contraction of actin and myosin filaments

Question 70

What does the contraction of the filaments (parturition) require?

Answer 70

Calcium

Question 71

Why is oestrogen stimulating the production of prostaglandins important for parturition?

Answer 71

The prostaglandins stimulate the production and release of calcium into the cytoplasm from intracellular stores

Question 72

What effect does progesterone have in relation to parturition?

Answer 72

Opposite effect to oestrogen Inhibits prostaglandin synthesis Inhibits oestrogen receptors

Question 73

At parturition, oxytocin will be released, what effect will this have?

Answer 73

It will bind to its receptor and open calcium channels allowing calcium ions to move in from outside

Question 74

What does prolactin do?

Answer 74

Promotes milk synthesis

Question 75

What does oxytocin do?

Answer 75

Promotes milk ejection

Question 76

How are prolactin and oxytocin linked neurologically?

Answer 76

They have the same neuroendocrine reflex