Reproduction: Uterus, uterine tubes and cervix Flashcards
Why is the uterus of a newborn girl bigger relative to her body size compared to when the girl is a toddler?
- Myometrium growth dependent on estradiol
- Newborn uterus has been exposed to high levels of maternal estradiol so myometrium grows in size
- When girl grows a few years older she isn’t exposed to maternal estradiol so myometrium decreases in size
What are the 3 layers of the uterus?
- Endometrium
- Myometrium
- Perimetrium
Briefly describe the changes that the myometrium grows through during childhood/puberty
- During childhood outer myometrial layer grows gradually during childhood
- Then during puberty the myometrium grows rapidly and the muscle fibres within it change configuration
What are the 3 myometrial layers and how are the muscle fibres orientated within each layer?
- Inner layer which has circular fibres
- Middle layer which has spiral fibres
- Outer layer which has longitudinal fibres
What parts of the endometrium remain after menstruation?
- Stromal matrix with small columnar cells that have glandular extensions
During the follicular phase of the menstrual cycle what hormone is mainly responsible for the growth of the endometrium?
Oestrogen
What changes occur to the endometrium as it proliferates during the follicular phase of the menstrual cycle?
- Endometrium proliferates from the stromal layer due to stromal cell division
- Stromal layer surface becomes ciliated
- Uterine glands expand and become tortuous
- Arteries and veins develop and proliferate
- Eventually develops progesterone receptors
What changes occur to the endometrium during the luteal phase of the menstrual cycle?
- Uterine glands increase in tortuosity (become twisted) and distend
- Glands then begin to secrete glycoproteins and lipids
- Increased vascular permeability
- Arteries/arterioles contract and grow tightly wound
Apart from hCG what other hormone is needed for the survival of the corpus luteum?
- LH
- hCG needed once progesterone secreted from corpus luteum causes decrease in LH levels due to negative feedback
Describe how the endometrial layer is “shed” during menstruation
- Lack of progesterone leads to prostaglandin release within endometrium
- This causes constriction of the arteries within endometrium which leads to hypoxia and then necrosis
- Vessels then dilate and bleeding ensues which leads to shedding of most of endometrium
After menstruation whay happens to the basal layer of endometrium that’s left behind?
- Basal layer (containing stromal matrix) is covered by extension of glandular epithelium
What are the 3 main sections of the uterine tube?
- Intramural section
- Isthmus
- Ampulla
The inside of the uterine tubes are lined with mucosa, there are 3 types of cells that make up this mucosa. What are these 3 cell types?
- Secretory cells - Secrete substances that interact with developing embryo
- Columnar ciliated epithelial cells - Contain cilia that help oocyte/developing embryo down uterine tube
- Non-ciliated Peg cells
Uterine tubes have several layers of smooth muscle. What are the layers of smooth muscle and what are the orientation of the muscle fibres in these layers?
- Inner layer - circular fibres
- Outer layer - longitudinal fibres
What is the outermost layer of the uterine tube called?
Serosa
How are the cells that line the uterine tubes able to differentiate during follicular phase of menstrual cycle?
- These cells express high numbers of oestrogen receptors which allow them to respond to increased oestrogen levels and differentiate
What changes occur to the cells that line the uterine tubes during the follicular phase?
- Cells increase in size/height
- Cilia develop
- Secretory cells become activated
During the luteal phase of the menstrual cycle what occurs to the cells that line the uterine tubes?
- Exposure to progesterone causes oestrogen receptors to be supressed
- This causes the cells that line the uterine tube to de-differentiate
How long does the oocyte remain in the uterine tube for?
Approximately 5 days
What things can cause damage/blockage of the lining of the uterine tube?
- Infection - Chlamydia
- Endometriosis
- Surgery
- Adhesions
What is endometriosis?
When endometrial tissue grows in areas other than the endometrium of the uterus such as the ovaries or uterine tubes
How can endometriosis lead to the blockage of the uterine tube?
- Endometrial cells/tissue implant themsleves within the uterine tube
- They then begin to respond to hormones just like they would if they were in the endometrium
- In response to progesterone the cells will bleed, shed and become inflammed which can lead to blockage of uterine tube
What can damage to the lining of the uterine tube result in?
- Pain
- Infertility
- Ectopic pregnancy
What is ectopic pregnancy?
When a developing embryo is unable to exit the uterine tube and so continues to grow/develop within the tube
