Uterus, uterine tubes and cervix Flashcards
1
Q
What is the basic physiology of reproduction/uterus?
A
- Egg is ovulated from ovary, fimbrae catches it and collects it
- Oocyte will be fertilised in the ampulla of the uterine tubes
- First week in the tube, the makes its way into the uterus
- Outer muscular layers of the uterus = myometrium, then inner layer (endometrium) is replaced once a month
- Sperm make way up the vagina, into the cervix and into the uterus. This fertilisation will take place in the uterine tubes - some will be chemoattracted to the oocyte to find their way
2
Q
What changes in the uterus and cervix are there?
A
- maternal steroids increase size of newborn uterus
- grows with height during infancy
- myometrium dependent on oestradiol
- corpus of uterus undergoes greater increase in size than cervix
- inner layer (endometrium) is shed during menses
- outerside is several layers of myometrium
- myometrium responds to oestrogen by growing
- newborn uterus is bigger (in proportion) than the uterus of a 4 year old. This is because the foetus’ uterus responds to the heightened maternal oestrogen
- By 4 it is back to its normal relative size
- increases in size so much in pregnancy that afterwards the uterus remains larger than normal
- parous adult (had kids) will have a larger uterus than nulliparous
- postmenopausal woman will have smaller uterus
3
Q
How does the myometrium change through life?
A
- outer muscular myometrium grows gradually throughout childhood
- increases rapidly in size and configuration during puberty
- changes in size through the cycle and capable of vast expansion during pregnancy - gives enough contraction to push the baby out
4
Q
How are the fibres of myometrium laid out?
A
- inner layer has circular fibres
- middle layer figure of 8/ spiral fibres
- outer layer longitudinal fibres
5
Q
How does the endometrium change in the menstrual cycle?
A
- First half of the cycle it proliferates and becomes about 15mm thick (under control of oestrogen)
- Around a week after ovulation the endometrium is mature and receptive, ready for implantation
- After ovulation, CL produces progesterone, causing the endometrium to differentiate and develop uterine glands - secrete GFs, adhesion molecules, hormones etc
- Blood supply becomes very tortuous - supplies tissue with lots of blood and O2
- If no implantation, then the CL dies and the endometrium is shed
- There are changes in glandular and epithelial cells throughout the cycle, after menstruation there is a stromal matrix with small columnar cells and simple, straight 2-3mm thick glandular extensions.
6
Q
What happens in the endometrial proliferative phase?
A
- Stimulated by oestradiol from the dominant follicle
- FSH causes growth of follicle, as it grows, it starts to produce oestrogen. This feeds back onto the hypothalamus and pituitary causing a reduction in FSH. The dominant follicle is then selected
- There is stromal cell division to make a ciliated surface
- Glands expand and become tortuous with increased vascularity from neoangiogenesis
- There is maximal cell division by 2 weeks
- When endometrium >4mm = induction of progesterone receptors and small muscular contractions of myometrium
7
Q
What happens in the endometrial secretory phase?
A
- Secretory phase is 2-3 days after ovulation - theca and granulosa of the follicle start to produce progesterone
- Progesterone has a differentiating effect on endometrium
- during secretory phase, endometrium matures and differentiates, secreting GFs, glycoproteins, adhesion molecules etc, lining the surface of endometrium for embryo to stick to.
- Blood supply increases and glands become more tortuous
- If there is pregnancy, the embryo produces hCG, maintaining the CL, stopping the menstrual cycle and stabilising pregnancy
- if no pregnancy, the CL will die after 14 days, stopping progesterone production
8
Q
Why might the CL regress?
A
- CL is stimulated by LH from the pituitary during luteal phase
- The fertilised oocyte becomes a blastocyst and produces hCG, which acts like LH on LH receptors and rescues the CL
- In the absence of hCG, the CL will die after 14 days, and falling levels of progesterone from the CL results in menstruation
9
Q
How does menstruation occur?
A
- Drop in progesterone causes PG release, which causes constriction of spiral arterioles
- This hypoxia causes necrosis
- Vessels then dilate and bleeding ensues
- Proteolytic enzymes are released from the dying tissue
- Outer layer of endometrium shed, 50% lost in 24hrs, normally lasts 4 days altogether
- Basal layer remains and is then covered by extension of glandular epithelium
- Oestrogen from follicle in next follicular phase starts cycle off again
10
Q
What are the 3 parts of the uterine tube?
A
- Intramural
- Isthmus
- Ampullary
11
Q
What are the different layers of cells in the uterine tube?
A
- Outer layer = serosa - visceral peritoneum
- Muscular layer - inner circular and outer longitudinal layers. Also has blood vessels and lymphatics
- Inner layer = mucosa. Has secretory, columnar ciliated epithelial and non-ciliated peg cells
12
Q
How do the cells in the uterine tubes change in response to oestrogen and progesterone?
A
- Give almost opposite reactions
- At first, we have oestrogen, giving growing follicles and proliferating endometrium, and so won’t really need the cilia activity yet.
- As oestrogen levels rise through the cycle, the cilia and secretory cells will become differentiated - cells swell, express more cilia and start secreting
- This allows the oocyte to pass through mid-cycle
- As progesterone levels rise during the latter stages, de-differentiation of the uterine tube occurs
13
Q
How is the egg transported along the uterine tube?
A
- beating of cilia, stimulated by growth by oestrogen
- rapid contractions of muscular layer, caused by oestrogen
14
Q
Where in the uterine tube does fertilisation usually occur?
A
- Ampulla
- Remains in tube for approx 5 days, going from 1 cell to about 150
15
Q
What is endometriosis?
A
- The presence of endometrial cells outside of the endometrium
- Means that the embryo can implant into other tissues, and still respond to the female hormonal cycle as if it were inside the uterus
- causes internal bleeding and pain
- If it is ectopic in the pelvis, it would have to move through the uterine tube - blocks tube
