Reproduction: Uterus, uterine tubes and cervix

Question 1

Why is the uterus of a newborn girl bigger relative to her body size compared to when the girl is a toddler?

Answer 1

• 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

Question 2

What are the 3 layers of the uterus?

Answer 2

• Endometrium
• Myometrium
• Perimetrium

Question 3

Briefly describe the changes that the myometrium grows through during childhood/puberty

Answer 3

• During childhood outer myometrial layer grows gradually during childhood
• Then during puberty the myometrium grows rapidly and the muscle fibres within it change configuration

Question 4

What are the 3 myometrial layers and how are the muscle fibres orientated within each layer?

Answer 4

• Inner layer which has circular fibres
• Middle layer which has spiral fibres
• Outer layer which has longitudinal fibres

Question 5

What parts of the endometrium remain after menstruation?

Answer 5

• Stromal matrix with small columnar cells that have glandular extensions

Question 6

During the follicular phase of the menstrual cycle what hormone is mainly responsible for the growth of the endometrium?

Answer 6

Oestrogen

Question 7

What changes occur to the endometrium as it proliferates during the follicular phase of the menstrual cycle?

Answer 7

• 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

Question 8

What changes occur to the endometrium during the luteal phase of the menstrual cycle?

Answer 8

• 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

Question 9

Apart from hCG what other hormone is needed for the survival of the corpus luteum?

Answer 9

• LH
• hCG needed once progesterone secreted from corpus luteum causes decrease in LH levels due to negative feedback

Question 10

Describe how the endometrial layer is “shed” during menstruation

Answer 10

• 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

Question 11

After menstruation whay happens to the basal layer of endometrium that’s left behind?

Answer 11

• Basal layer (containing stromal matrix) is covered by extension of glandular epithelium

Question 12

What are the 3 main sections of the uterine tube?

Answer 12

• Intramural section
• Isthmus
• Ampulla

Question 13

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?

Answer 13

• 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

Question 14

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?

Answer 14

• Inner layer - circular fibres
• Outer layer - longitudinal fibres

Question 15

What is the outermost layer of the uterine tube called?

Answer 15

Serosa

Question 16

How are the cells that line the uterine tubes able to differentiate during follicular phase of menstrual cycle?

Answer 16

• These cells express high numbers of oestrogen receptors which allow them to respond to increased oestrogen levels and differentiate

Question 17

What changes occur to the cells that line the uterine tubes during the follicular phase?

Answer 17

• Cells increase in size/height
• Cilia develop
• Secretory cells become activated

Question 18

During the luteal phase of the menstrual cycle what occurs to the cells that line the uterine tubes?

Answer 18

• Exposure to progesterone causes oestrogen receptors to be supressed
• This causes the cells that line the uterine tube to de-differentiate

Question 19

How long does the oocyte remain in the uterine tube for?

Answer 19

Approximately 5 days

Question 20

What things can cause damage/blockage of the lining of the uterine tube?

Answer 20

• Infection - Chlamydia
• Endometriosis
• Surgery
• Adhesions

Question 21

What is endometriosis?

Answer 21

When endometrial tissue grows in areas other than the endometrium of the uterus such as the ovaries or uterine tubes

Question 22

How can endometriosis lead to the blockage of the uterine tube?

Answer 22

• 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

Question 23

What can damage to the lining of the uterine tube result in?

Answer 23

• Pain
• Infertility
• Ectopic pregnancy

Question 24

What is ectopic pregnancy?

Answer 24

When a developing embryo is unable to exit the uterine tube and so continues to grow/develop within the tube

Question 25

What are the 2 main ways of testing for uterine tubal patency?

Answer 25

• Laparoscopy
• Hystero Salpingo-contrast Sonography (HyCoSy)

Question 26

Explain how laparoscopy and dye is used to test for tubal patency?

Answer 26

• You place a cannula into the uterus and inject the uterus with a blue dye
• You then place a laparoscope through the abdomen and use the forceps to manipulate the uterine tubes
• You then use the camera to look at the uterine tube to see if the blue dye makes its way down the uterine tubes
• If the dye doesn’t appear in a uterine tube you know that tube is blocked

Question 27

Explain how Hystero Salpingo-contrast Sonography (HyCoSy) is used to test for tubal patency

Answer 27

• Insert cannula into the uterus and inject an ultrasound contrast dye into the uterus
• You then use an ultrasound probe to track the progess of the dye through the uterine tubes

Question 28

What is the name of the cells that cover the ectocervix?

Answer 28

Non-keratinized stratified squamous epithelium

Question 29

The endocervical canal is lined with endocervical mucosa, what cells make up the endocervical mucosa?

Answer 29

Columnar mucous cells

Question 30

What substance do the endocervical cells secrete and why?

Answer 30

• Viscous alkaline cervical mucus
• Mucus is a protective barrier to infection

Question 31

What effect does oestrogen have on the cervix during the follicular phase of the menstrual cycle?

Answer 31

• Increase in vascularity of cervix
• Oedema (more water released from cervix)

Question 32

What changes occur to the cervix/cervical mucus by the mid-point of the menstrual cycle (ovulation)?

Answer 32

• Mucous to become less viscous.
• Change in mucous composition -glycoproteins align to form microscopic channels allowing sperm to swim through them

Question 33

What effect does progesterone have on the cervix during the luteal phase of the menstrual cycle?

Answer 33

• Mucous become viscous (reduced water content)
• Glycoproteins now form mesh like structure - forms barrier to spem

Question 34

How is infection in the vagina prevented?

Answer 34

• Layers of epithelial cells shed constantly and ‘flow’ downwards with the endocervical secretions
• These secretions are acidic