7. UTERUS, UTERINE TUBES & LUTEAL PHASE Flashcards
1
Q
What are the three layers of the uterus lining?
A
- Perimetrium - outer layer
- Myometrium - muscular layer involved in contractions
- Endometrium - shed during menstruation
2
Q
Describe the changes in the uterus & cervix with age?
A
- The uterus & cervix grow with height during infancy
- The uterus of a newborn can be larger than that of a toddler, because the foetus would have been exposed to the high levels of oestrogen in utero, causing proliferation
- Myometrial growth is dependent on E2 (estradiol)
3
Q
Describe the growth of the myometrium
A
- The outer muscular myometrium grows gradually throughout childhood/infancy
- It grows rapidly during puberty & responds to oestrogen specifically E2
- The myometrium size changes throughout the menstrual cycle & can grow substantially during pregnancy
4
Q
What are the three fibres of the myometrium?
A
- Inner circular fibres - arranged concentrically
- Middle figure 8 or spiral fibres
- Outer layer longitudinal fibres
5
Q
What are the properties of the endometrium?
A
- Endometrium is very thin in childhood but begins to thicken during puberty
- Dependent on sex steroids & responds to cyclical hormone changes
- Most of endometrium is shed during menstruation
- But the basal layer of the endometrium remains & is covered by an extension of glandular epithelium
6
Q
What are the two endometrial phases of the menstrual cycle?
A
- ENDOMETRIAL PROLIFERATIVE PHASE
- ENDOMETRIAL LUTEAL PHASE
- The two phases are divided by ovulation
7
Q
What happens during the endometrial proliferative phase?
A
- The proliferative phase of the endometrium is also the follicular phase of the ovary
- The endometrium thickens in response to oestrogen in the proliferative phase. The oestrogen is produced by the granulosa cells of the growing follicle
- When the endometrium is larger than 4mm, progesterone receptors are induced and small muscular contractions of the myometrium occur
8
Q
What are the 3 changes during the proliferative phase?
A
- Stromal cell division occurs producing small, columnar epithelial cells
- Glands become tortuous & length
- Increased vascularity - formation of new blood vessels (neoangiogenesis)
9
Q
What happens during the endometrial secretory phase?
A
- The secretory phase of the endometrium is also the luteal phase of the ovary
- Progesterone dominates the endometrial phase
- The gradual rise in progesterone results in decreased cell division but increased differentiation
10
Q
What 4 changes occur during the secretory phase?
A
- Glands increase in size & swell
- Glands secrete lipids & glycoproteins
- Oedema occurs, increased vascular permeability due to arterioles contracting & becoming tighlty coiled
11
Q
How does regression of the corpus luteum trigger menstruation?
A
- The corpus luteum produces progesterone & has LH receptors, so LH is needed to maintain the corpus luteum
- If fertilisation occurs, the oocyte will form a blastocyst & the blastocyst will produce human chorionic gonadotrophin which binds to the LH receptors, maintaining CL.
- Maintaining CL, maintains progesterone & the endometrium
- But if fertilisation doesn’t occur, the high levels of progesterone produced will cause negative feedback causing LH levels to decline
- The drop in LH will cause the corpus luteum to regress forming the corpus ablicans
- Progesterone will no longer be produced & progesterone will decline triggering menstruation
12
Q
Describe the process of menstrual bleeding?
A
- The decline in progesterone (due to corpus luteum degradation) levels will trigger menstruation
- As the endothelial cells of the uterus break down, they release inflammatory prostaglandins
- The prostaglandins cause constriction of the spiral arterioles, leading to hypoxia. The hypoxia leads to necrosis of endothelial cells. The blood vessels then dilate causing bleeding
- The dying tissue releases proteolytic enzymes
- Outer layer of endometrium is shed (functional layer), 50% lost in first 24 hours
- Oestrogen produced by follicles in the next follicular phase will start the cycle again
13
Q
What are three segments of the uterine tube?
A
- AMPULLA - where fertilisation occurs
- ISTHMUS
- INTRAMURAL PORTION - closest to the uterus
14
Q
What three histological layers comprise the uterine tube?
A
- MUCOSA
- MSUCLARIS
- SEROSA
15
Q
What three cell types are found in the mucosa layer of uterine tubes?
A
- Secretory cells - secrete growth factors, nutrients & signalling molecules for embryo development
- Columnar ciliated epithelial cells - beat to help move oocyte along uterine tube
- Non-ciliated peg cells - release a secretion which lubricates tube to protect oocyte
16
Q
What are the characteristics of the muscularis layer of eth uterine tube?
A
- Arranged into two layers: inner circular fibres & outer longitudinal fibres
- Consists of blood vessels & lymphatics
17
Q
What are the characteristics of the serosa layer of the uterine tube?
A
- Serosa layer is the outer layer containing mesothelial cells
18
Q
What changes occur to the cells of the uterine tube during the follicular phase & ovulation?
A
- Oestrogen dominates in the follicular phase. Epithelial cells express many oestrogen receptors & undergo differentiation in response to oestrogen
- When ovulation occurs, the ciliated & secretory cells will have differentiated, so that they can carry out their functions when the oocyte is released
19
Q
What changes occur to the cells of the uterine tube during the luteal phase?
A
- Progesterone dominates in the luteal phase
- Progesterone counter-acts the effects of oestrogen such as ciliation
- After a few days of progesterone exposure, the oestrogen receptors are suppressed
- The cells decrease in height so that they don’t come in to contact with the oocyte, this helps to prevent late fertilisation
20
Q
What are the consequences of damage to the uterus tube lining?
A
- Damage to the uterus uterus lining can occur due to infection, surgery, adhesions or endometriosis
- Consequences:
1. Pain
2. Infertility
3. Ectopic pregnancy
21
Q
Give two ways tubal patency can be tested
A
- Tubal patency is when the uterine tubes are not blocked
1. Laparascopy & dye
2. HyCoSY - Hystero Salpingo contrast sonography
22
Q
Describe the principles of a laparoscopy & dye
A
- Uterine canula inserted into vagina & a blue dye is inserted.
- If there are no blockages in the uterine tube, the blue dye will emerge near the fimbriae. But if it’s blocked it won’t show up
- The blue dye can be visualised with a laparascopy
23
Q
Describe the principles of Hystero-Salpingo contrast sonography
A
- HyCOSy can be injected into the cervix via the vagina
- It is an opaque dye that can be visualised with ultrasound, so it’s less invasive than a laparoscopy
24
Q
What are the properties of the ectocervix?
A
- Contains squamous epithelial cells
- Covered with non-keratinised stratified squamous epithelial
25
What physiological changes occur in the cervix during the follicular phase?
- Oestrogen produced in the follicular phase causes changes in the vascularity of the cervix & oedema
26
What physiological changes occur in the cervix during ovulation?
- Oestrogen in the mid-cycle makes the cervical mucus less viscous & permeable to sperm
- The mucus contains glycoproteins which forms microscopic channels allowing sperm to swim up
27
What physiological changes occur in the cervix luteal phase?
- Progesterone in the luteal phase causes mucus to become viscous & less permeable to sperm
- The glycoproteins in the mucus from a mesh like structure acting as a barrier to sperm
28
What are the properties of the vagina?
- Thick walled tube approximately 10cm
| - Lined with squamous epithelial cells, also contains glycoproteins
29
What are bartholins glands?
- Bartholins glands secrete mucus to lubricate the vagina. They are the equivalent of the bulbo-urethral glands in males
- Located posterior to & left & right to vaginal opening
