What is the difference between oocytes, eggs and ovum?
They are all the same
What are the main female reproductive organs?
Vagina, uterus, Uterine tubes and ovaries
What is the physical description of the vagina?
An elastic muscular tube extending from the cervix to the exterior of the body
What are the functions of the vagina?
Eliminates menstrual fluid, receives the penis during sexual intercourse and holds the spermatozoa before they pass into the uterus
What is the shape of the uterus?
A small pear shaped organ
What is the function of the uterus?
Pathways for sperm transport
provides mechanical protection, nutritional support and waste removal for the developing embryo and fetus
Contracts enabling the fetus to be ejected during birth
Source of menstrual flow
What is the normal and abnormal positioning of the uterus?
Normal = anti flexed (90º angle to the cervix pointing anteriorly)
Abnormal = retroflexed (pointing posteriorly)
Can/how does a retroflexed uterus correct itself?
During child bearing it will go back to be anti-flexed
What is the uterine tube?
A tube that connect the ovaries to the uterus
What is the function of the uterine tube?
Provides a rich nutritive environment for the sperm, oocyte and developing embryo while it transports these into the uterus
What are the two types of cells in the uterine tube? What do each do?
Ciliated and non-ciliated
The ciliated grab the egg and transport it down into the uterus (FYI there is also smooth muscle that perform peristaltic action), the non-ciliated provides nutrients for the egg
What can cause the ciliated cells in the uterine tube to be less effective? What can this lead to?
Women who smoke, are older and have pre-eisting damage in their uterine tube (i.e. from STI's) have cilia that don't beat as much therefore the egg doesn't move down the tube fast enough which can lead to an ectopic pregnancy
What are the ovaries?
Small oval structure at the end of the uterine tube
What is the function of the ovaries?
Stores and maintains the eggs
What is the cervix?
The narrow passage way into the uterus
What does the cervix have in it most of the month and why?
Normally blocked off with a mucosal plug to prevent sperm, bacteria etc. getting into the reproductive tract
What is an old fashioned method for predicting fetal growth?
Some women are able to feel the fundus of their uterus (the top of their uterus) and the height in centimetres is approximately the number of weeks of gestation (FYI greater than usual height may indicate twins, breech birth etc., less than may indicate underdevelopment)
Label the diagram
What is the endometrium?
The mucosal inner membrane layer of the uterus
What is the structure of the endometrium? What is the function of each component?
Inner functional zone, stratum functionalis (on the inside of the uterus) - Contains most of the uterine glands
Outer basilar zone, stratum basalis (i.e. base of endometrium) - attaches the stratum functionalis to the myometrium
How does the structure of the endometrium change? Why?
In the lead up to ovulation the endometrium develops a thicker stratum functionalis so that the uterus is more well nourished for the potential implantation of an embryo. During menstruation this thicker layer of stratum functionalis is removed
Label the diagram
What do the fimbriae of the uterine tube do? How do they do it?
They pick up the oocyte from the ovaries and transport it into the uterine tube
They are covered in beating cilia which pick up the oocyte
Label the diagram, YOU MUST KNOW ALL OF THESE
FYI not all of these structures are present at once, this is just following the developmental cycle of a primordial follicles to a mature follicle
What is a primordial follicle?
The oocyte/egg once surrounded by a single layer of flat follicular cells
What are primary follicles?
The primordial follicle when it has grown larger and more columnar in shape
What causes the primordial follicle to develop into a primary follicle?
Follicle stimulating hormone (FSH)
What important structures develops during the primary follicle? What are their functions at this stage?
-Zona pellucide, controls the entry of sperm (i.e. only 1 sperm of the same species)
-Thecal cells, help maintain the shape of the egg
What does a primary follicle develop into? What structures develop?
Develops into a secondary follicle which develops a follicular antrum and the thecal cells develops
How does a follicular antrum develop?
A viscous follicular fluid coalesces to form a single follicular antrum
How do the thecal cells from the primary follicle change in the secondary follicle?
The inner theca become more glandular and develop a blood supply (becomes theca interna) and the outer theca becomes more fibrous developing into a more supportive structure (theca externa)
What important hormone does theca interna produce?
What does the secondary follicle develop into? What happens for this development?
The mature (Graafian or pre-ovulatory) follicle
A single secondary follicle (because many have developed into a secondary follicle FYI) is matures increasing the amount of follicular fluid
How is the mature follicle connected to the ovary?
It is connected to the rim of the peripheral granulose cells by a thin stalk of cells
What happens to the mature follicle?
It undergoes ovulation
What is ovulation?
The follicle ruptures carrying with with it the egg and the surround mass of cumulus cells (fluffy cells surrounding the oocyte/egg)
What causes ovulation?
The increasing size of the follicle and its position in the cortex causes it to bulge from the ovarian surface
What happens to the oocyte after ovulation?
It is collected by the cilia on the fimbria (see diagram for what they are)
After ovulation what happens to the follicle?
The antrum breaks downs and undergoes luteinisation
What is luteinisation? What happens in this process?
The conversion of an empty follicle cell into a major endocrine gland
The empty follicle becomes highly vascular and forms the corpus luteum (hormone secreting cells)
What hormones are produced by the corpus luteum?
How long does the corpus luteum work for? What happens when it stops working?
For a few weeks if fertilisation is unsuccessful (otherwise longer)
If not utilised then it will degrade into a corpus ablicans where it is reabsorbed back into the stromal tissue of the ovary over months
What enables the corpus luteum to work past its normal life aspen?
Human chorionic gonadotrophin hCG, produced by the chorion of the embryo after about 8 days of fertilisation
How does the uterus respond to high levels of oestradiol?
It develops a thick layer of stratum functionalism (the uterus layer that secretes stuff)
What is the menstrual cycle?
The cyclical process of ovulation
How long does the average menstrual cycle last?
What are the three phases of the menstrual cycle?
Menstrual, follicular and luteal phase
What is the menstrual phase?
When the stratum functionalism is removed from the uterus
What is the follicular phase?
Where the follicle is developing leading up to ovulation
What is the luteal phase?
Where the empty follicle is converted into a major endocrine organ for producing progesterone
What part of the menstrual cycle varies the most? How does it vary with age?
The follicular phase varies the most (6-16 days) and gets shorter as the female ages
Why do humans have a menstrual cycle? What do other animals do instead?
Humans have a very thick endometrium layer (i.e. the stratum functionalis) and it needs to be removed, also removes any bacteria that may develop
Most other mammal species re-absorb their endometrium layer
Label the hormones on the diagram
What is the interaction between Progesterone and Estrogens to Follicle stimulating hormone? What does this mean for the menstrual cycle?
There is a negative feedback loop
As the corpus luteum degenerates (i.e. produces less progesterone) the new primordial follicle begins to develop
The menstrual cycle is a negative feedback loop which allows for the cyclical process of menstruation. When is the exception to this? Explain what is happening?
Just prior to ovulation
At ~day 12 a threshold concentration of estradiol is exceeded and if this is maintained for ~36 hours then is is a oestrogen mediated positive feedback trick for GnRH (gonadotropin releasing hormone) which causes the increased release of LH (Luteinising hormone)
What does an increase in LH lead to (i.e. what important hormone is developed and how? How does this then affect itself?)?
Leads to ovulation resulting in the formation of the corpus luteum which cause increasing progestogen which initiates a negative feedback loop inhibition GnRH which then decreases FSH (follicle stimulating hormone) and LH
Label the diagram