Uterus, Uterine tube and Cervix

Question 1

What are the different uterine layers?

Answer 1

Endometrium: inner lining

Myometrium: middle muscular layer

Perimetrium: outer layer

Question 2

Describe the stucture of the myometrium.

Answer 2

3 layers of muscle fibres:

• inner layer of circular fibres
• middle layer with figure of 8 spiral fibres
• outer layer with longitudinal fibres

*allow contraction in every direction

Question 3

Describe the structure of the endometrium.

Answer 3

The inner epithelial lining of the uterus that thickens and develops during the menstrual cycle, into which a fertilised ovum can implant, and which sheds during mensuration if a pregnancy does not occur.

Question 4

What maintains the thickness of endometrium?

Answer 4

progesterone produced by the corpus luteum after ovulation

Question 5

Why does the endometrium shed?

Answer 5

when there is no fertilisation, the corpus luteum dies and progesterone falls, so the endometrium sheds, resulting in the stromal matrix with small columnar cells and glandular extensions

Question 6

Describe the endometrial Proliferative Phase.

Answer 6

Proliferation/Thickening of endometrium

• stimulated by oestradiol from dominant follicle in follicular phase
• stromal cell division, ciliated surface
• glands expand and become tortuous, increased vascularity, neoangiogenesis
• maximal cell division by days 12-14

Question 7

What is the proliferative phase known as in the ovary?

Answer 7

Follicular phase

Question 8

How does thickening of the endometrium affect the myometrium?

Answer 8

when endometrium is >4mm there is induction of progesterone receptors and small muscular contractions of the myometrium

Question 9

Describe the Secretory Phase.

Answer 9

Differentiation of Endometrium

• 2-3 days after ovulation where the rise in progesterone from corpus luteum causes more differentiation than proliferation of endometrium
• glands increase in tortuosity & distend, secreting glycoproteins and lipids
• increased vascular permeability leading to oedema
• myometrial cells enlarge and movement is suppressed

Question 10

What is the secretory phase known as in the ovary?

Answer 10

luteal phase

Question 11

What is Lifespan of corpus luteum?

Answer 11

14 days

Question 12

Describe the Regression of corpus luteum.

Answer 12

If no fertilisation

• no hCG to bind LH receptors and stimulate corpus luteum survival
• corpus luteum dies, no more progesterone, endometrium is shed, causing menstruation

Question 13

Why is hCG needed to rescue corpus luteum?

Answer 13

hCG binds LH receptors to stimulate progesterone production needed for maintenance of endometrium

Endogenous LH can’t rescue corpus luteum due to the high progesterone levels exerting negative feedback, decreasing LH levels

Question 14

How does menstruation occur?

Answer 14

As corpus luteum dies:

• prostaglandins are released causing constriction of spiral arterioles, starving tissue of oxygen
• vessels then dilate and necrotic tissue bleeds, releasing proteolytic enzymes
• outer endometrial layer shed
• basal endometrial layer remains and is covered by extension of glandular epithelium

Question 15

Describe the Structure of Uterine Tube.

Answer 15

MUCOSA- outer surface
>Secretory epithelial cells
>Ciliated epithelial cells
>Non-ciliated Peg cells

MUSCULARIS- smooth muscle
>inner circular layer
>outer longitudinal layer

SEROSA-connective tissue
>outer protective layer

Question 16

What is the Effect of proliferative phase on cells of uterus tube.

Answer 16

Ciliated and Secretory Epithelial Cell Differentiation

• stimulated by high oestrogen levels
• so cilia beat and egg is nourished during ovulation

Question 17

What is the Effect of secretory phase on cells of uterus tube?

Answer 17

Ciliated and Secretory Epithelial Cell De-differentiation

-high progesterone levels suppress oestrogen receptors

Question 18

What is the effect of Oestrogen and Progesterone on Endometrium and Uterine Tube?

Answer 18

Oestrogen in follicular phase:

• proliferates endometrium
• differentiates uterine tube

Progesterone in luteal phase:

• differentiates endometrium in luteal phase
• de-differentiates uterine tube

Question 19

After ovulation, what collects the egg?

Answer 19

fimbrae

Question 20

Where does fertilisation occur?

Answer 20

ampulla

Question 21

Where does early embryo development take place?

Answer 21

in the uterine tube (first 5 days)

Question 22

How can the uterine tube be damaged?

Answer 22

Infection, endometriosis, surgery or adhesions may cause blockage or damage to ciliated epithelia, resulting:

• pain
• infertility
• ectopic pregnancy

Question 23

What is endometriosis?

Answer 23

Growth of endometrial tissue outside of uterus

-could block uterine tube

Question 24

What is Tubal Patency?

Answer 24

How open the fallopian tubes are

Question 25

How is tubal patency tested?

Answer 25

Two main ways to test for tubal patency: - Laparoscopy and Dye - Hyesterosalpingo-Contrast Sonography (HyCoSy)

Question 26

Describe Laparoscopy and Dye.

Answer 26

- cannula placed through cervix, into uterus and blue dye injected - blue dye fills tubes and appears on fimbrae - laporoscope inserted through abdomen to look for blue dye - if no blue dye present, tube is blocked

Question 27

Describe Hystero Salpingo-Contrast Sonography (HyCoSy).

Answer 27

- cannula placed through cervix, into uterus and ultrasound contrast dye injected - ultrasound probe used to track the progress of the dye down the tube

Question 28

Which test is more accurate in testing tubal patency?

Answer 28

Although the Laparoscopy and Dye test is more invasive, it gives a more visual inspection of the pelvis, providing more accurate results (e.g. if we think there is endometriosis/surgical adhesions/infection then we can see the inflammation, whereas we won't be able to see it via ultrasound).

Question 29

What is the cervix?

Answer 29

The opening to the uterus

Question 30

What is the ectocervix?

Answer 30

part of the cervix lined with non-keratinized stratified squamous epithelium

Question 31

What is the endocervix?

Answer 31

mucous membrane lining the cervical canal -contains tubular glands which empty viscous alkaline mucus into lumen to stop bacteria and infection getting into the uterus, but still allowing passage of sperm

Question 32

Describe the Cervix composition in follicular phase.

Answer 32

high oestrogen causes: | -less viscous/more watery mucous which contains glycoproteins which form microscopic channels which sperm swim up

Question 33

Describe the Cervix composition in luteal phase.

Answer 33

high progesterone causes: - reduced watery secretions/more viscous and thick mucus - glycoproteins form mesh-like structure acting as sperm barrier

Question 34

Describe the structure of the vagina.

Answer 34

thick walled tube lined by specialised squamous epithelial cells warm damp environment containing glycoprotein

Question 35

How does the vagina prevent infections?

Answer 35

- layers of epithelial cells shed constantly - secretions from cervix and transudation from vaginal epithelium - acidic secretions providing anti-microbial protection

Question 36

Why is the vagina damp?

Answer 36

Bartholins glands located slightly posterior and to the left&right of the vagina opening secrete mucus to lubricate the vagina