Uterine tubes and Cervix Flashcards
What changes occur to the uterus and cervix?
POSTNATAL
maternal steroids increase size of neonatal uterus
INFANCY
uterus grows with height during infancy
PUBERTY and MENSTRUAL CYCLE
- myometrium is E2-dependent
- Uterine corpus undergoes a bigger increase in size that the cervix
What is the function of the 3 muscular layers in the myometrium?
Allows dynamic muscular contraction in various directions
How does the myometrium change during development?
CHILDHOOD
outer muscular myometrium gradually grows
PUBERTY
myometrium rapidly increases in size and configuration
MENSTRUAL CYCLE
changes in size at various points in cycle
PREGNANCY
capable of vast expansion
How are the muscular fibres arranged in the 3 layers of the myometrium?
INNER layer
circular fibres
MIDDLE layer spiral fibres (figure of 8)
OUTER layer
longitudinal fibres
How does the endometrium change through development?
CHILDHOOD
very thin, begins to thicken at puberty
MENSTRUAL CYCLE
thickness dependent on steroids, will change throughout cycle
P causes mainly differentiation of glandular and epithelial tissue in secretory phase
most endometrium lost during periods
post-menstruation - stromal matrix with small columnar cells with glandular extensions (2-3mm thickness)
Glands are simple and straight
How does the corpus luteum support endometrial differentiation during the luteal phase?
(= secretory phase)
CL secretes progesterone
P promotes differentiation of upper layer of endometrium and angiogenesis (creating tortuous vessels - spiral arteries)
this provides an enriched vascular supply to the endometrium
and heightens the secretory gland activity
What is the endometrial proliferative phase?
[Days 5-14]
= follicular phase of ovary
stimulates by E2 from growing follicle
endometrial changes (max. days 12-14):
stromal cell division
ciliated surface
glands expand and become tortuous due to angiogenesis
when endometrium >4mm:
induction of P receptors
small muscular contractions in myometrium
What maintains the corpus luteum in the secretory phase?
LH-R signalling on the CL
which then allows CL to make P
However, P secretion acts via negative feedback to suppress LH release (from ant. pituitary)
This loss of LH eventually leads to CL atresia (14 days after ovulation)
What is the endometrial secretory phase?
[days 15-28]
= luteal phase of ovary
2-3 days after ovulation
gradual increase in P causes reduction in cell division (of endometrium)
glands become more tortuous and distend
-> secretion of glycoproteins and lipids
PG action (?)
- > oedema
- > increased vascular permeability
- > arterioles contract and grow tightly wound
myometrial cells enlarge and movement is suppressed
blood supply increases
When doe corpus luteum regression occur?
CL stimulated by LH from ant. pituitary during luteal phase
fertilised oocyte becomes and blastocyst and produces hCG which binds to the LH-R (and therefore maintains CL)
However, if oocyte is not fertilised then loss of P secretion from CL causes atresia and then menstruation
Where is hCG synthesised?
from trophoblast cells in the fertilised embryo (blastocyst)
What causes menstruation?
reduction in P causes release of PGs
(vasoconstrictory F2a and Tx) PG release causes spiral arteries to constrict
these are end-arteries so cause hypoxia and then necrosis
proteolytic enzymes are released from the dying endometrial tissue
outer layer of endometrium is shed (50% lost in 24h)
basal (stromal) layer remains, then covered by extension of glandular epithelium
E2 from follicle (next follicular phase) imitates cycle again
What is normal menstruation pattern?
can vary vastly
3-5 days, usually 4+
<80ml is considered normal
What are the 3 layers of the uterine tube?
Mucosa (inner)
Muscularis (middle)
Serosa (outer
What does the uterine tube mucosa contain?
secretory cells
columnar ciliated epithelial cells
non-ciliated peg cells
What does the uterine tube muscularis contain?
inner circular layer
outer longitudinal layer
blood vessels
lymphatic vessels
What are the different regions of the uterine tube called?
lateral: - fimbriated infundibulum (nearest ovaries) - ampulla - isthmus - intramural \: medial
What is the nature of the intramural region of the uterine tubes?
most medially located
contains more muscular layers
What is the nature of the ampullary region of the uterine tubes?
located most laterally (nearest to fimbriated infundibulum)
contains more glandular layers
What changes occur to the uterine tube cells during follicular phase?
= proliferative phase
epithelial cells express high E2 receptors
undergo differentiation in responde to E2 increase in mid-cycle
What changes occur to the uterine tube cells during ovulation?
oocyte can only pass down the tube at mid-cycle
cilia beat and secretory cells are active
this occurs along with muscular contractions down there uterine tube
these are all stimulated by E2
What changes occur to the uterine tube cells during luteal phase?
= secretory phase
after few days expo to P , E2 receptors are suppressed and E2 levels drop (from mid-luteal onwards)
How does oestrogen have different effects on different tissues in the uterus?
ENDOMETRIUM
E2 mediates proliferation
UTERINE TUBES
mediates differentiation
same hormone but different receptor isoforms (E3a vs E3b) ?
What occurs during fertilisation?
fertilisation occurs most commonly in the ampulla of the uterine tube
embryo remains in the tube for ~5d
damage to tube lining by infection, endometriosis, surgery or adhesions
this can cause blockage or damage to ciliated epithelia, causing:
- pain
- infertility
- ectopic pregnancy
How may uterine tubal patency be examined?
- laprascopy and dye
(abdominal approach) - hysterosalpingo-contrast sonography (HyCoSy)
(vaginal approach)
What is the histological structure of the cervix?
= muscular structure capable of vast expansion
ENDOCERVICAL MUCOSA
~3mm thick
lined with single layer of columnar mucous cells
numerous tubular mucous glands
ECTOCERVIX
covered with non-keratinised stratified squamous epithelium
similar to the squamous epithelium lining vagina
What is the function of the tubular mucous glands in the endocervical mucosa?
to secrete viscous alkaline mucus into the cervical lumen
- protective barrier to infection
- but allows passage of sperm
What are the different regions of the cervix?
[near corpus uterus] - internal os - endocervical canal - endocervical mucsal - ectocervix - external os [vagina]
Where are the vaginal fornices?
part of the vaginal cavity
corners surrounding the ectocervix
What happens to the cervix during the follicular phase?
E2 causes change in cervical vascularity and oedema
PERI-OVULATION
mid-cycle E2 surge reduced cervical mucous viscosity
- glycoproteins in mucous align to form microscopic channels that allow sperm to swim up
What happens to the cervix during the luteal phase?
P secretion causes:
- reduced secretion of mucous
- mucous become more viscous
- glycoproteins now form mesh: barrier to sperm and microorganisms
- one MoA for oral contraceptives (promote thick mucous plug)
What is the histological structure of the vagina?
thick walled tube ~10cm in length
lined by squamous epithelial cells
warm, damp environment containing glycoprotein
What mechanisms protect the vagina from infection?
- layers of epithelium slough and flow downwards with secretions
- cervical secretions and transudate
- secretions change during cycle and are acidic (antimicrobial protection)
What are the Bartholin’s glands?
located posterior and either side of the vaginal opening
secrete mucus to lubricate vagina
homologous to bulbourethral glands in males
