Uterus, Uterine tube and Cervix Flashcards
What are the different uterine layers?
Endometrium: inner lining
Myometrium: middle muscular layer
Perimetrium: outer layer
Describe the stucture of the myometrium.
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
Describe the structure of the endometrium.
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.
What maintains the thickness of endometrium?
progesterone produced by the corpus luteum after ovulation
Why does the endometrium shed?
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
Describe the endometrial Proliferative Phase.
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
What is the proliferative phase known as in the ovary?
Follicular phase
How does thickening of the endometrium affect the myometrium?
when endometrium is >4mm there is induction of progesterone receptors and small muscular contractions of the myometrium
Describe the Secretory Phase.
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
What is the secretory phase known as in the ovary?
luteal phase
What is Lifespan of corpus luteum?
14 days
Describe the Regression of corpus luteum.
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
Why is hCG needed to rescue corpus luteum?
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
How does menstruation occur?
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
Describe the Structure of Uterine Tube.
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
What is the Effect of proliferative phase on cells of uterus tube.
Ciliated and Secretory Epithelial Cell Differentiation
- stimulated by high oestrogen levels
- so cilia beat and egg is nourished during ovulation
What is the Effect of secretory phase on cells of uterus tube?
Ciliated and Secretory Epithelial Cell De-differentiation
-high progesterone levels suppress oestrogen receptors
What is the effect of Oestrogen and Progesterone on Endometrium and Uterine Tube?
Oestrogen in follicular phase:
- proliferates endometrium
- differentiates uterine tube
Progesterone in luteal phase:
- differentiates endometrium in luteal phase
- de-differentiates uterine tube
After ovulation, what collects the egg?
fimbrae
Where does fertilisation occur?
ampulla
Where does early embryo development take place?
in the uterine tube (first 5 days)
How can the uterine tube be damaged?
Infection, endometriosis, surgery or adhesions may cause blockage or damage to ciliated epithelia, resulting:
- pain
- infertility
- ectopic pregnancy
What is endometriosis?
Growth of endometrial tissue outside of uterus
-could block uterine tube
What is Tubal Patency?
How open the fallopian tubes are
How is tubal patency tested?
Two main ways to test for tubal patency:
- Laparoscopy and Dye
- Hyesterosalpingo-Contrast Sonography (HyCoSy)
Describe Laparoscopy and Dye.
- 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
Describe Hystero Salpingo-Contrast Sonography (HyCoSy).
- cannula placed through cervix, into uterus and ultrasound contrast dye injected
- ultrasound probe used to track the progress of the dye down the tube
Which test is more accurate in testing tubal patency?
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).
What is the cervix?
The opening to the uterus
What is the ectocervix?
part of the cervix lined with non-keratinized stratified squamous epithelium
What is the endocervix?
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
Describe the Cervix composition in follicular phase.
high oestrogen causes:
-less viscous/more watery mucous which contains glycoproteins which form microscopic channels which sperm swim up
Describe the Cervix composition in luteal phase.
high progesterone causes:
- reduced watery secretions/more viscous and thick mucus
- glycoproteins form mesh-like structure acting as sperm barrier
Describe the structure of the vagina.
thick walled tube lined by specialised squamous epithelial cells
warm damp environment containing glycoprotein
How does the vagina prevent infections?
- layers of epithelial cells shed constantly
- secretions from cervix and transudation from vaginal epithelium
- acidic secretions providing anti-microbial protection
Why is the vagina damp?
Bartholins glands located slightly posterior and to the left&right of the vagina opening secrete mucus to lubricate the vagina
