Pregnancy, Parturition and lactation

Question 1

Where does fertilisation occur?

Answer 1

In the ampulla

Question 2

What connects the fimbriae and ampulla to the uterus?

Answer 2

The isthmus

Question 3

What is surrounded by granulosa cells?

Answer 3

The oocyte

Question 4

How do cilia and smooth muscle aid fertilisation?

Answer 4

The oocyte has to travel through a physical gap between the fimbriae and the ovary.
Cilia and smooth muscle aid the gap jump

Question 5

Describe sperm capacitation in the female reproductive system

Answer 5

Attachment of the acrosome to attachment proteins on the egg
Membrane of sperm and oocyte fuse
Penetration causes an increase of calcium

Question 6

What does the increase in calcium levels trigger in sperm capacitation?

Answer 6

Triggers the second mitotic division

Question 7

What attachment proteins does the acrosome attach to?

Answer 7

ZP3 (zona pellucida 3)

Question 8

Function of the oocyte cortical reaction?

Answer 8

Penetration to trigger the second meiotic division
Prevents polyploidy

Question 9

What does haploid pronuclei fusion form?

Answer 9

A diploid zygote

Question 10

Describe pre-implantation.

Answer 10

Conceptus in the oviduct, undergoing mitosis, lasts 3 days ->
Morula is formed after 3 days (solid mass of 12 cells) ->
Morula forms a blastocyst ->
Blastocyst become implanted after 6 days

Question 11

Function of trophectoderm?

Answer 11

Forms further structures in embryo

Question 12

Function of the fluid filled inner mass?

Answer 12

The inner mass becomes the embryo

Question 13

What are the stages of endometrium invasion?

Answer 13

1. Hatching
2. Apposition
3. Adhesion
4. Invasion

Question 14

What are the stages of endometrium invasion?

Answer 14

1. Hatching
2. Apposition
3. Adhesion
4. Invasion

Question 15

Describe the stages of endometrium invasion

Answer 15

1. Hatching
   - Zona pellucida disintegrates
2. Apposition
   - Cell bodies line up alongside endometrial tissue
3. Adhesion
   - Integrin proteins attach between maternal and endometrial tissue and the conceptus
4. Invasion
   - The blastocyst outer layer invades endometrial tissue to form the inner cytotrophoblast and the outer syncytiotrophoblast

Question 16

How is the decidua formed?

Answer 16

The blastocyst promotes endometrial stromal cells to form decidua (predecidualisation)

Question 17

What does the decidua contain?

Answer 17

Glands and immune cells
Blood and lymph vessels
Glycogen for nourishment

Question 18

Function of the decidua?

Answer 18

Reduces inflammation
Decreases rejection of the allogenic embryo

Question 19

When does the placenta form?

Answer 19

After attachment of embryo in the uterus

Question 20

What structure do cytotrophoblasts and syncytiotrophoblast form?

Answer 20

Villi and microvilli projecting into the maternal blood

Question 21

What is maternal and foetal blood separated by in mature placenta?

Answer 21

Foetal capillary endothelium
Mesenchyme
Cytotrophoblasts
Syncytiotrophoblast

Question 22

Why does the placenta contain fluid-filled cavities?

Answer 22

The cavities fill with blood and cause a reduction in the force and velocity of pulsile blood from the mother

Question 23

How is glucose transported from maternal to foetal blood?

Answer 23

Facilitated diffusion

Question 24

How are amino acids transported from maternal to foetal blood?

Answer 24

2nd degree active transport

Question 25

How are vitamins transported from maternal to foetal blood?

Answer 25

Active transport

Question 26

How are LDL, hormone and antibodies transported from maternal to foetal blood?

Answer 26

By receptor mediated endocytosis

Question 27

What is oxygen exchange between maternal and foetal blood facilitated by?

Answer 27

Foetal haemoglobin has a higher affinity for oxygen

Question 28

What is lacune?

Answer 28

Blood collected into venules to form veins without a capillary phase

Question 29

How are creatinine and waste urea transported from foetus to mother?

Answer 29

Diffusion from amniotic fluid, removed by maternal blood

Question 30

What are the changes in hormones during trimester 1?

Answer 30

HCG is at its highest on day 8, stimulates production of progesterone, oestrogen and prolactin (stimulate corpus luteum) LH rescues the corpus luteum

Question 31

What are the hormonal changes in trimester 2 and 3?

Answer 31

HCG coordinates glucose to FA, ketone storage and mammary gland development. Progesterone synthesised from circulatory cholesterol Oestrogen synthesises foetal placenta

Question 32

How is progesterone synthesised in the foetus?

Answer 32

Cholesterol moves into the placenta -> Cholesterol turns into pregnenolone -> Pregnenolone turns into progesterone in the placenta and then moves into the foetus

Question 33

How is estriol synthesised?

Answer 33

Cholesterol from the mother moves into the placenta -> Cholesterol turns into pregnenolone -> Pregnenolone transfers into the foetus -> The foetal adrenal gland catalyses pregnenolone to DHEA-sulfate -> The foetal live catalyses DHEA-sulfate to 16-OH-DHEA-sulfate -> This transfers back to the placenta as estriol

Question 34

What is the parturition stage 0?

Answer 34

From conception to initiation of parturition

Question 35

Describe what happens in parturition stage 0.

Answer 35

Uterus relaxes and is insensitive to uterotonic hormones Progesterone supresses myometrial contractions Braxton hicks contractions occur

Question 36

When can Braxton hicks contractions take place?

Answer 36

Once the uterus has reached a critical size

Question 37

What is parturition stage 1?

Answer 37

Preparation for birth, prior to labour

Question 38

What happens in parturition stage 1?

Answer 38

Upregulating HP adrenal axis causes a cortisol release -> This upregulates oestrogen and progesterone ratio, increasing contractility of myometrium -> Oestrogen stimulates the release of prostaglandin

Question 39

Function of prostaglandin

Answer 39

Promotes gap junction formation

Question 40

What happens to the cervix during parturition stage 1?

Answer 40

The cervix softens, thins and dilates

Question 41

What genes are expressed during parturition stage 1?

Answer 41

Contraction associated proteins give muscle tone to the uterus and has receptors for oxytocin

Question 42

What enzymes are released during cervical gene expression?

Answer 42

Enzymes that hydrolyse collagen matrix to soften

Question 43

What is parturition stage 2?

Answer 43

Stimulation/labour/birth

Question 44

Function of oxytocin during stage 2 parturition?

Answer 44

Causes contractions

Question 45

What are the stages of labour and delivery?

Answer 45

1. Dilation - Pelvic ligaments relax, softening and widening 2. Expulsion of foetus - Oxytocin levels increase 3. Placental - Placenta detaches from decidua

Question 46

What is parturition stage 3?

Answer 46

Recovery from birth

Question 47

What happens in stage 3 parturition to prevent haemorrhage?

Answer 47

Vasoconstriction of spiral arteries

Question 48

How long does the endometrial cycle take to re-establish after birth?

Answer 48

3-5 months

Question 49

What is colostrum?

Answer 49

The first milk - High fat and protein content - Antibodies

Question 50

What is milk?

Answer 50

A fat emulsion in aqueous solution - Sugar - Protein - Cations and anions

Question 51

Structure of a breast?

Answer 51

Alveoli - secretory breast unit Contractile myoepithelial cells and adipose tissue

Question 52

How is lactation controlled by hormonal control during pregnancy?

Answer 52

Oestrogen and progesterone promote breast growth and development -> Oestrogen stimulates prolactin which produces milk (lactogenesis) -> This usually promotes breast growth but this is inhibited during pregnancy

Question 53

Where is prolactin stimulated?

Answer 53

In the anterior pituitary

Question 54

How is lactation controlled by hormones postpartum?

Answer 54

Mammogenic - promotes cell proliferation (oestrogen) Lactogenic - initiates milk production (prolactin) Galactokinase - stimulates myoepithelium contraction (oxytocin) Galactopoietic - maintains milk (prolactin and cortisol

Question 55

What hormone inhibits the ovarian cycle?

Answer 55

Downregulation of GnRH

Question 56

What inhibits dopamine release from hypothalamus?

Answer 56

Prolactin