AAP Reproductive System 2

Question 1

What are the structures of the female reproductive system?

Answer 1

• ligaments
• ovaries
• oviducts
• uterus
• cervix
• vagina
• vulva

Question 2

What is the function of the ligaments in the reproductive system?

Answer 2

• suspend ovaries, oviducts and uterus

Question 3

What are the types of ligaments in the reproductive system?

Answer 3

• broad ligaments –> sheets of peritoneum
• round ligament of the uterus –> fibrous tissue and smooth muscle in lateral fold of the broad ligament on each side
• suspensory ligament of the ovary –> secure ovary to lateral walls of the pelvis

Question 4

What are the ovaries?

Answer 4

• female gonads

Question 5

Where are the ovaries located?

Answer 5

• they lie on each side of the dorsal part of the abdominal cavity, caudal to the kidneys

Question 6

What are the functions of the ovaries?

Answer 6

• to produce ova/eggs

- to act as an endocrine gland –> secretes the hormone oestrogen and progesterone

Question 7

What do oestrogen and progesterone do (basic)?

Answer 7

• maintain female secondary sexual characteristics

Question 8

What are the oviducts?

Answer 8

• AKA uterine/fallopian tubes
• small tubes extending from the tips of the uterine horns
• finger-like projections at the tip known as fimbriae which capture the ovum released from ovaries
• oviduct also provides a site for fertilization
• cilia inside the uterine tube slowly move the fertilized ova towards the uterus (takes 3-4 days)

Question 9

What is the uterus (structure)?

Answer 9

• Y-shaped structure
• uterine body forms the base of the Y
• uterine horns form the arms

Question 10

What are the layers of the uterus?

Answer 10

• endometrium: inner mucosal layer (secretes mucus & other substances, allows for implantation of a fertilized egg)
• Myometrium: middle layers of smooth muscle
• Perimetrium: outer visceral layer of peritoneum

Question 11

What are the functions of the uterus?

Answer 11

• provide a site where the embryos can develop into a new animal
• provide the means whereby the developing embryos can receive nutrition from the mother –> via the placenta

Question 12

What is the cervix?

Answer 12

• a short, thick-walled muscular sphincter, which connects the uterine body with the vagina
• the lumen of the cervix is known as the cervical canal
• it is normally tightly closed and dilates only to allow the passage of sperm, or foetus during birth
• during pregnancy, the canal is blocked by a mucous plug which protects the embryos from infection

Question 13

What is the vagina?

Answer 13

• the tube that leads to the external opening
• receives penis at breeding
• serves as the birth canal at birth

Question 14

What is the vulva?

Answer 14

• the external part of the female reproductive system

- other structures such as the clitoris and labia are found in this area

Question 15

What is the ovarian cycle?

Answer 15

• ovum is not constantly produced in the ovary

- their production involves a complex sequence of events in a repeating fashion –> this is known as the ovarian cycle

Question 16

What are uniparous species?

Answer 16

• one mature ovum produced per cycle

- e.g. horse, cow, human

Question 17

What are multiparous species?

Answer 17

• multiple ova produced per cycle

- cat, dog, sow

Question 18

Describe the ovarian cycle.

Answer 18

• the primary follicle, which is an immature oocyte (ovum/egg cell) is surrounded by a layer of follicular cells
• the development of follicle cells are stimulated by follicle stimulating hormone (AKA FSH)
• follicular cells thicken and multiply into multiple layers (known as granulosa cells)
• follicle grows rapidly as granulosa cells multiply
• granulosa cells produce increasing amounts of oestrogen as follicle becomes larger
• fluid-filled spaces form between granulosa cells
• spaces gradually merge into one large fluid-filled space (known as antrum)
• when follicle reached its maximum size, its called a mature follicle
• looks like a large blister-like structure on the surface of the ovary
• at this stage, oestrogen production peaks
• subsequently, surface of mature follicle weakens and the follicle ruptures, releasing the ovum into the oviduct
• antral fluid is also released and the empty follicle fills with blood

Question 19

What are granulosa cells?

Answer 19

• Granulosa cells are follicular cells that thicken and multiply into multiple layers

Question 20

What is ovulation?

Answer 20

• ovulation occurs spontaneously in most species as a result in rising levels of luteinizing hormone (LH) from pituitary gland
• in some species, ovulation occurs after breeding (cat, rabbit)

Question 21

What is corpus luteum

Answer 21

• the empty follicles will develop into corpus luteum
• this process is influenced by continued stimulation of hormone LH
• corpus luteum produces the hormone progesterone (necessary for maintenance of pregnancy)
• if ovum implants in uterus, endocrine signal to ovary to cause corpus luteum to be maintained
• if no implantation takes place, the corpus luteum regresses

Question 22

What is the estrous cycle/heat cycle

Answer 22

• the rhythmic cycle of events that occurs in sexually mature non-pregnant female mammals
• animals such as horses, pigs and dogs work on an estrous cycle (not menstrual cycle
• they are only in heat (sexually active) every 5/6 months
• the heat cycle is highly regulated by hormones

Question 23

What is the estrus cycle/heat cycle regulated by?

Answer 23

• hormones

Question 24

What are the stages in the heat cycle?

Answer 24

• proestrus
• estrus
• metestrus/diestrus
• anestrus

Question 25

What happens during proestrus?

Answer 25

- lasts 9 days - there is increased blood concentration of oestrogen causing swelling of the vulva - bloody vulval discharge is present - at this stage females release pheromones to attract males - females usually does not allow the male to mate but becomes increasingly receptive - increases the layers of vaginal epithelial cell - as a negative feedback, increased oestrogen level suppresses the production of FSH and increases the production of LH

Question 26

What happens during estrus?

Answer 26

- lasts 9 days - ovulation at day 2 - female will present herself to the male and allow mating - estrogen level starts to decline - LH reaches to its peak level and triggers ovulation (release the ovum from the ovary) - corpus luteum forms in place of the released ovum and secrete progesterone

Question 27

What happens during metestrus/diestrus?

Answer 27

- if pregnant (50-60 days), delivery at ~63 days from ovulation - if not pregnant (90days) - corpus luteum continues to secrete progesterone --> maintaining pregnancy in the gestating bitch if pregnant; if not pregnant--> causing the uterine to return to a normal state in the non-pregnant bitch

Question 28

What happens during anestrus?

Answer 28

- lasts 5 months - sexual inactivity - in non-pregnant bitches, progesterone level gradually declines - in pregnant bitches, the drop of progesterone will trigger whelping (giving birth) - subsequently, the uterine enters a state of inactivity - at the late stage of anestrus, some of the primary follicles will begin to develop to repeat the cycle

Question 29

What is the difference between the ovarian cycle and the heat cycle?

Answer 29

- the heat cycle is the rhythmic cycle of events in a female animal, during which she becomes sexually active, including physiological changes: such as vulva swelling & behavioural changes, such as mating - the ovarian cycle describes events that occur, particularly in the follicles of the ovary