Lecture 15: Reproduction in females

Question 1

Describe the vagina structure and function

Answer 1

This is the muscular 7.5-9 cm long tube that extends from the cervix to the exterior of the body.
It has 3 main functions: receives the penis, holds spermatozoa before they pass into the uterus and forms the lower portion of the birth canal

Question 2

Describe the Uterus function

Answer 2

Function is to provide mechanical protection, nutritional support and waste removal for the developing fetus.

Question 3

Describe the layers of ‘metrium’ in the uterus

Answer 3

Outermost layer is the stratum functionalis which contains the uterine glands and is lost throughout menstruation. Then the stratum basalis which stays constant and is attached to the myometrium. Myometrium is a smooth muscle wall thats contractions help expel the fetus.

Question 4

Describe the Fallopian (uterine) tubes structure (basic)

Answer 4

The tube is lined by epithelium made up of cilliated and non cilliated secretory columnar cells. The mucosa is surrounded by concentric layers of smooth muscle.

Question 5

Describe the Fallopian (uterine) tubes function

Answer 5

Function: transport of spermatozoa, oocyte and embryo by cillary movement and peristaltic contractions. As well as having lipids and glycogen for a nutritive environment.

Question 6

Describe the Ovaries structure and function

Answer 6

Oval organ about 5-10g comprising of 3 regions.
Outer ovarian cortex containing all ovarian follicles, the central ovarian medulla (which contains ovarian stroma and steroid producing cells) and the inner hilum which allows blood vessels and nerves to enter.

Question 7

What is ovarian stroma

Answer 7

A dense irregular connective tissue

Question 8

What does an anteflexion or retroflexion mean

Answer 8

Most women have an anteflexed uterus which is perpendicular to the vagina but 20% have a retroflexed uterus which is kind of straight, following the vaginal tube

Question 9

Describe the structure of the Uterus

Answer 9

Pear shaped organ 30-40g. The top part is called the Fundus and the bottom is called the Cervix.

Question 10

What is the function of cervical mucus

Answer 10

Most of the time cervical mucus becomes thick plugging the cervix so no bacteria or sperm can enter the uterus from the vagina. Only a few days prior to ovulation does the mucus change to allow the entry of sperm

Question 11

How was fetal growth predicted in the old days

Answer 11

The height of the fundus from the pubic bone was used to predict the number of weeks a fetus had gestated. With 1cm = 1 week. It could be also used to check for twins, gestational diabetes, wrong position, intrauterine growth restriction

Question 12

Describe the 4 kind of regions of the fallopian tube

Answer 12

Closest to the uterus is the Isthmus.
Middle where fertilisation occurs: Ampulla
End Closest to the ovary :infundibulum.
Fingerlike projections at end : fimbriae. These are covered in cillia that are beating constantly and increase frequency to collect the oocyte when ovulated.

Question 13

Define ectopic pregnancy

Answer 13

When fertilised embryo is implanted in any tissue other than uterine wall

Question 14

List the 5 steps of follicular development in order and the two possible outcomes

Answer 14

Primordial follicle, primary follicle, secondary follicle, Mature (Graafian/pre-ovulatory follicle)
Ovulation, Corpus Luteum (luteinisation)
OUtcomes:
Fertilisation & futile

Question 15

Describe the primordial follicle stage

Answer 15

The ovaries are filled with millions of primordial follicles from birth. These are oocytes surrounded by a single layer of squamous follicular cells.

Question 16

Describe the Primary- Pre antral follicle stage

Answer 16

Some follicles grow and others die. The ones that start to grow, follicular cells become one layer of cuboidal granulosa cells

1. FSH stimulates the oocyte to get bigger and then get more layers of granulosa cells.
2. Oocyte secretes glycoproteins which form a translucent layer called the Zona pellucida.
3. Ovarian stroma cells called Thecal cells begin to form around the follicle

Question 17

Describe the main events at the Secondary follicle stage

Answer 17

As granulosa cells proliferate, they produce a viscous follicular fluid that coalesces to form a single follicular antrum (lake).

2. Granulosa cells specialise
3. Theca develops into 2 layers

Question 18

What happens to the granulosa cells at secondary follicle stage

Answer 18

The corona radiata is made from the inner most 2-3 layers of granulosa cells becomes firmly attached to the zona pellucida.
The rest of the loosely associated granulosa cells are called cumulus oophorus

Question 19

What does the theca develop to at the secondary follicle stage

Answer 19

The thecal cells move from the medulla to form the inner glandular and highly vascularised theca interna ( involved with the increased production of estradiol) and the fibrous outer capsule called theca externa

Question 20

Descrube main events in the mature (Graafian or preovulatory) follicle stage

Answer 20

The follicular antrum grows, the oocyte becomes suspended in fluid.
It is connected to the rim of peripheral granulosa cells by a thin stalk of cells

Question 21

Descrube main events in the ovulation stage

Answer 21

The follicle starts to bulge out the ovarian surface bc it gets larger and its at the cortex of the ovarian stroma.

2. The follicle then ruptures and this slowly releases the oocyte+ surrounding mass of cumulus cells.
3. The oocyte is collected by cillia on the fimbria which sweep the cumulus mass into the uterine tube

Question 22

Descrube main events in the Corpus luteum (luteinisation) stage of the ovary

Answer 22

After ovulation, the antrum breaks down and the basement membrane between the granulosa and thecal layers breaks down and blood vessels invade.
2. The granulosa cells form lutein (yellow) cells, this is associated with increasing secretion of progestagens

Question 23

Describe what happens to corpus luteum in a futile cycle

Answer 23

Corpus luteum will only stay for 2 weeks. After which no fertilisation will lead to degeneration, forming the corpus albicans which is absorbed back into the stromal tissue of the ovary over weeks to months.

Question 24

Describe what happens to corpus luteum in a fertile cycle

Answer 24

The corpus luteum will persist if the zygote survives and divides. hCG produced by chorion of the embryo 8days after fertilisation stops deterioration of the corpus luteum. This allows it to keep producing progesterone + estrogen to support pregnancy

Question 25

What is the difference between a futile cycle and fertile cycle

Answer 25

Futile will lead to corpus luteum degenerating and therefore no more progesterones to prepare stable secretory endometrium for implantation as in a fertile cycle. Instead it is shed in menstruation.

Question 26

Name and compare the phases of the ovarian cycle vs the endometrial cycle

Answer 26

The ovarian cycle has 2 phases, follicular phase (day 1 to ovulation) and luteal phase (ovulation to menstruation).
In contrast, the uterine menstrual cycle has 3 phases: Menstruation (0-5) proliferative in response to estradiol and secretory in response to progestrone

Question 27

what cells produce what estrogens in the ovaries

Answer 27

The granulosa cells around the chosen oocyte. This is estradiol

Question 28

What is the fixed phase of the menstrual cycle - how long and therefore how can menstrual cycle length vary

Answer 28

luteal phase is a fixed 14 days, however as a women ages the length of the follicular phase changes

Question 29

Why does a human need a menstrual

Answer 29

The female reproductive tract has 2 main functions. To produce oocyte and reproductive hormones. And as well to incubate embryo

Question 30

What is the first 2 key events of menstrual cycle ( starting at just before the menstrual bleed)

Answer 30

1. The corpus luteum regresses with oestrogen and progesterone levels low. There is a slight increase of FSH
2. FSH stimulation leads to increase follicular growth

Question 31

What is the #3,4 key events of menstrual cycle ( starting at day 6/7)

Answer 31

3. The dominant follicle has been selected. it has lots of thecal and granulosa cells that produce a rise in oestradiol
4. Oestradiol suppress FSH and LH production in the pituitary

Question 32

The levels of Progesterone and oestrogens increase and decrease oppositely to which two other hormones

Answer 32

FSH and LH

Question 33

What is the #5,6,7 key events of menstrual cycle ( starting at around day 12)

Answer 33

5. Oestrogen levels by the nearly mature follicle rise by ~day 12, a theshold concentration of oestradiol is exceeded. If this is maintained for around 3 days, there is a temporary switch from a negative to positive feedback.
6. Oestrogen mediated positive feedback triggers a rise in GnRH, leading to a surge in LH
7. The rapid rise of LH induces ovulation- release of the oocyte

Question 34

What does the positive feedback switch caused by oestrodial mean

Answer 34

Instead of oestrodial increasing causing a decrease in GnRH and LH/ FSH, instead it helps to stimulate both the hypothalamus and anterior pituitary to produce MORE GnRH and LH/FSH

Question 35

What is the #8,9,10 key events of menstrual cycle (starting at around day 17)

Answer 35

8. Corpus Luteum develops and this increases progesterone.
9. Elevated progesterone levels inhibit GnRH, leads to decreased FSH + LH as it reinstates the negative feedback loop
10. The Corpus luteum demises and therefore progesterones start to decrease