Uterus, uterine tubes and cervix Flashcards
What’s the difference between the myometrium and endometrium?
- endometrium is renewable every month - the layer shed during menses - mucous membrane that lines the uterus
- on the outside is the muscular myometrium, several layers
What hormone is the myometrium dependent on?
oestraidol
What undergoes greater increase in size than the cervix?
corpus of uterus
Describe growth of myometrium through life and pregnancy
- outer muscular myometrium grows gradually throughout childhood
- increases rapidly in size + configuration during puberty
- changes in size through the cycle
- capable of vast expansion during pregnancy
Describe the structure of the myometrium
- inner layer - circular fibres
- middle layer - figure of 8 or spiral fibres
- outer layer - longitudinal fibres
The endometrium is dependent on steroids, it responds cylically to hormone changes. Can be seen + measured on an US scan. Describe the growth of the endometrium through childhood, puberty + menstruation
- very thin in childhood
- begins to thicken at puberty
- changes in glandular + epithelial cells through cycle
- at menstruation most of endometrium is lost
What is the histological structure of the endometrium after menstruation?
- stromal matrix
- with small columnar cells
- with glandular extensions 2-3mm thick
- glands are simple + straight
Describe the structural characteristics of the endometrial proliferative phase and what it is stimulated by?
- by oestradiol from the dominant follicle
- stromal cell divison, ciliated surface
- glands expand + become tortuous
- increased vascularity
- neoangiogenesis
- maximal cell divison by days 12-14
What happens when the endometrium is >4mm thick?
- induction of progesterone receptors
- small muscular contractions of the myometrium
What phase follows the endometrial proliferative phase?
Endometrial secretory phase (luteal phase of ovary)
When is the endometrial secretory phase?
2-3 days after ovulation
What happens in the endometrial secretory phase?
- gradual rise in progesterone causes a reduction in cell divison
- glands increase in tortuosity + distend
- secretion of glycoproteins + lipids commences
- oedema, inc vasc perm, arterioles contract + grow tightly wound
- myometrial cells enlarge + movement is suppressed
- blood supply increases
What is the corpus luteum stimulated by?
- by LH from pituitary during luteal phase
What does the fertilised oocyte become and what does it produce?
- blastocyst
- produces hCG
- acts like LH ie. on LH receptor, and ‘rescues’ the CL
- in absence of this, falling levels of steroid from CL results in menstruation
Describe the events of menstruation
- prostaglandin release -> constriction of spiral arterioles
- hypoxia -> necrosis
- vessels then dilate + bleeding ensues
- proteolytic enzymes released from dying tissue
- outer layer of endometrium shed, 50% lost in 24hrs, up to 80ml is considered normal
- bleeding normally lasts 4+ days
- basal layer remains + is covered by extension of glandular epithelium
- oestrogen from follicle in next follicular phase starts cycle off again
How does the mucosa differ at various points across the uterine tube?
- intramural - secretory
- isthmus - columnar ciliated epithelial
- ampullary - non-ciliated peg
Where does fertilisation occur in the uterine tube?
Ampulla
Describe changes undergone by cells lining the uterine tubes over the cycle - when can the oocyte pass here?
- epithelial cells undergo differentiation in response to oestradiol increase in height mid-cycle
- oocyte can only pass during mid-cycle
- after a few days of exposure to progresterone, oestrogen effects are overcome causing decrease in height mid-luteal onwards
How is the egg transported along the uterine tube?
- by beating of cilia, stimulated to grow by oestrogen
- rapid contractions of muscular layer caused by oestrogen
There are high number of oestrogen receptors present in the follicular phase. How are these receptors suppressed?
- oestrogen receptors suppressed by progresterone
- by mid-luteal phase, even if an egg was released it would be unable to pass as there is no transportation of the egg at this point
How long does the egg remain in the tube for?
5 days approx
Damage to lining of the tube by infection, endometriosis, surgery or adhesions may cause blockage or damage to ciliated epithelia, resulting in what 3 things?
- pain
- infertility
- ectopic pregnancy
Describe the basic/general structure of the cervix
- muscular structure capable of great expansion
- mucosa 2-3mm thick
The cervix has many secretory glands producing mucous. What is this for?
- protective barrier to infection
- however has to allow passage of motile sperm
