Uterus, Uterine Tubes And Cervix Flashcards
Uterine tubes
uterine appendages leading from the ovaries into the uterus
Uterus
hormone-responsive secondary sex organ of the reproductive system known as the womb
Myometrium
muscular wall of the uterus
Endometrium
inner epithelial layer of the uterus
Laparoscopy and dye
invasive test of tubal patency
Hystero Salpingo-contrast Sonography (HyCoSy)
non-invasive test of tubal patency
Cervix
narrow neck-like passage forming the lower end of the uterus
Changes in uterus & cervix
Maternal steroids increase size of new-born uterus.
Grows with height during infancy.
Myometrium dependent on estradiol.
Corpus of uterus undergoes greater increase in size than cervix.
diagram
Myometrium explained
Outer muscular myometrium grows gradually throughout childhood.
Increases rapidly in size and configuration during puberty.
Changes in size through the cycle. Capable of vast expansion during pregnancy.
diagrams
Inner layer circular fibres.
Middle layer figure of 8 or spiral fibres.
Outer layer longitudinal fibres.
Endometrium
Very thin in childhood. Begins to thicken at puberty.
Dependent on steroids and responds cyclically to hormone changes.
Estrogen principally causes growth in proliferative phase. Can be seen and measured on an ultrasound scan. Good ‘bioassay’ of estradiol level…7-16mm.
Changes in glandular and epithelial cells through the cycle. Progesterone causes mainly differentiation in secretory phase.
At menstruation most of the endometrium is lost.
After menstruation - stromal matrix with small columnal cells with glandular extensions 2-3mm thick glands are simple and straight.
Endometrial proliferative phase
Proliferative phase (follicular phase of ovary) following menses.
Stimulated by estrogen from the growing follicle.
Stromal cell division, ciliated surface. Glands expand and become tortuous, increased vascularity, neoangiogenesis
maximal cell division by days 12-14.
When endometrium >4mm, induction of progesterone receptors and small muscular contractions of the myometrium.
Endometrial secretory phase
Secretory phase (luteal phase of ovary)
2-3 days after ovulation, the gradual rise in progesterone causes a reduction in cell division.
Glands increase in tortuosity and distend…secretion of glycoproteins and lipids commences.
Oedema, increased vascular permeability arterioles contract and grow tightly wound.
Myometrial cells enlarge and movement is suppressed blood supply increases.
Regression of the corpus luteum
Corpus luteum stimulated by LH from pituitary during luteal phase.
The fertilised oocyte becomes a blastocyst and produces human chorionic gonadotrophin (hCG) which acts like LH ie on LH receptor, and ‘rescues’ the CL.
In the absence of this, falling levels of steroid from the CL results in menstruation.
Menstruation
Prostaglandin release causes constriction of spiral arterioles.
Hypoxia causes necrosis.
Vessels then dilate and bleeding ensues.
Proteolytic enzymes released from the 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 and is then covered by extension of glandular epithelium.
Estrogen from follicle in next follicular phase starts cycle off again.
Uterine tube
Intramural, Isthmus,Ampullary, Mucosa
- Secretory
- Columnar ciliated epithelial
- Non-ciliated Peg
Muscularis Inner circular & outer longitudinal layers. Blood vessels & lymphatics Serosa Outer layer
diagrams
Changes in cells lining the uterine tubes
diagrams
Epithelial cells express high numbers of estrogen receptors & undergo differentiation in response to estradiol increase in height mid-cycle.
After a few days of exposure to progesterone the estrogen receptors are supressed and estrogen effects are overcome causing decrease in height mid-luteal onwards.
Oocyte can only pass down the tube during mid-cycle. Cilia beat and secretory cells are active along with muscle layer contractions, all in response to estrogen.
Fertilisation & early
embryo development
Egg remains in the tube for approximately 5 days
Fertilisation occurs in ampulla
Damage to lining of the tube by infection, endometriosis, surgery or adhesions may cause blockage or damage to ciliated epithelia, resulting in…
pain
infertility
ectopic pregnancy
Tubal patency
diagrams
Cervix
Muscular structure capable of great expansion.
The endocervical mucosa is about 3mm thick, lined with a single layer of columnar mucous cells, containing numerous tubular mucous glands which empty viscous alkaline mucus into the lumen.
Protective barrier to infection…
However, it has to allow passage of motile sperm.
The ectocervix is covered with nonkeratinized stratified squamous epithelium, resembling the squamous epithelium lining the vagina.
Cervix – Follicular phase
Estrogen in the follicular phase causes…Change in vascularity of cervix and oedema.
Mid-cycle estrogen levels cause change in mucous to become
less viscous.Change in mucous composition.
Mucus contains glycoproteins glycoproteins which become
aligned and form microscopic channels.
Sperm swim up the channels!
Cervix – luteal phase
Progesterone in luteal phase causes…Reduced secretion and viscous mucous (reduced water content).
Glycoproteins now form mesh like structure: acts as barrier to sperm and microogranisms.
One mechanism of action of oral contraceptives.
Vagina
Thick-walled tube approx 10cm.
Lined by specialised ‘squamous epithelial’ cells.
Warm damp environment containing glycoprotein…
Susceptible to infection, which is prevented by…Layers of epithelial cells shed constantly and ‘flow’ downwards with the secretions.
Secretions are from cervix and transudation from vaginal epithelium.
Secretions change with cycle and are generally acidic providing anti-microbial protection.
Bartholins glands located slightly posterior and to the left and right of the opening of the vagina secrete mucus to lubricate the vagina and are homologous to bulbourethral glands in males.
