Uterus

Question 1

Changes in uterus & cervix

Answer 1

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.

Question 2

Myometrium

Answer 2

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

Inner layer circular fibres.
Middle layer figure of 8 or spiral fibres.
Outer layer longitudinal fibres.

Question 3

Endometrium

Answer 3

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 columnar cells with glandular extensions 2-3mm thick
glands are simple and straight.

Question 4

Endometrial proliferatiive phase

Answer 4

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.
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

Question 5

Regression of the corpus lutem

Answer 5

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.

Question 6

Menstruation

Answer 6

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.

Question 7

Uterine tube

Answer 7

Mucosa
1.	Secretory 
2.	Columnar ciliated epithelial
3.	Non-ciliated Peg
Muscularis
Inner circular & outer longitudinal layers. 
Blood vessels & lymphatics
Serosa 
Outer layer

Question 8

Changes in cells lining the uterine tubes

Answer 8

Epithelial cells express a high number of estrogen receptors & undergo differentiation in response to estradiol increase in height mid-cycle
Oocyte can only pass down the tube during mid-cycle. cilia beat and secretory cells are active doing with muscles layers contractions, all in response to estrogen

After a few days of exposure to progestogen the estrogen receptors are overcome causing a decrease in height mid-luteal onwards

Question 9

Fertlisation & early embryo development

Answer 9

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

Question 10

Cervix

Answer 10

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.

Question 11

Cervix - follicular phase

Answer 11

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!

Question 12

Cervix luteal phase

Answer 12

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.

Question 13

Vagina

Answer 13

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.