Female repro pt 1 Flashcards
What are the two main phases of the estrous cycle?
- Follicular phase
- Luteal phase
What happens in the follicular phase?
Estradiol is predominant and antral follicles develop
What happens in the luteal phase?
Progesterone is predominant and corpus luteum develops
What are the five distinct phases?
- Proestrus
- Estrus
- Metestrus
- Diestrus
- Anestrus
What happens during proestrus?
Start of estrous is marked by increasing estradiol and decreasing progesterone. Antral follicle maturation under LH, FSH and estrogen
What happens during estrus?
Estradiol is at highest concentration. Display of sexual receptivity and ovulation occurs at the end
How can you get a silent ovulation?
In seasonal breeders following anestrus there is no peak in progesterone and estradiol they will not display any mating behavior because they are not acting together on the brain
What happens in metestrus?
Decreasing estradiol concentration and increase progesterone. Get luteinization CH develops and then to CL
What happens during diestrus?
High progesterone and low estradiol due to mature CL. This suppresses estrus behavior. Longest portion
What hormone leads to mating behavior?
Estradiol
What is anestrus?
Female is not going through the estrous cycle due to insufficient GnRH secretion leading to insufficient LH and FSH levels
What can cause anestrus?
- Seasonal breeders
- Pregnancy/ postpartum
- Lactation
- Stress and pathology
- insufficient nutrition
What does polyestrus mean?
Continually cycle through the year
What is seasonally polyestrus?
Cycle during the spring (long day) or fall (short day) but in anestrus the remainder of the uear
What is monoestrus?
Cycle about 1 cycle per year
Do dogs have metestrus?
No, estrus occurs after estradiol peak where progesterone levels are rising and estrus is defined by sexual receptivity
What is induced ovulators?
Ovulation triggered by copulation not positive feedback on the surge center. Cycle back from proestrus to estrus
What are examples of induced ovulators?
Cats (queens)
What is the difference between menstrual and estrous cycle?
- Endometrial sloughing (menses)
- Sexual receptivity (estrous: estrus; Menstrual: uniform)
- Follicular phase (50% menses)
- PGF 2 alpha for luteolysis (Estrous from uterus, menses from ovary)
Describe the flow of hormones during the follicular phase.
- Proestrus starts with withdrawal of progesterone caused by luteolysis
- GnRH is turned back on with the withdrawal of progesterone
- FSH and LH get secreted
- LH binds to theca cells and they produce testosterone
- FSH binds to granulosa cells and they make estradiol from the testosterone.
- estradiol increases and causes negative feedback on GnRH
- Estradiol levels increase due to folliculogenesis
Describe the hormones during ovulation?
- Estradiol increases and causes positive feedback on the surge center but shuts of GnRH
- GnRH from the surge center and causes a release of FSH (most gets inhibited by Inhibin) and LH
- Surge of LH triggers ovulation
How does a surge in LH cause ovulation?
Causes lysis of the follicle
Describe the hormones during the luteal phase?
- Ovulation causes the follicle to form a CH and eventually a CL.
- CL causes theca and granulosa cells to stop working together to make estradiol
- Theca and granulosa cells start making progesterone
- Progesterone provides negative feedback on the tonic center suppressing GnRH and FSH/LH
- Cycle is paused as long as CL is viable
What causes luteolysis?
The uterus releases pulses of PGF2a and goes to the ovary via the uteroovarian vein and ovarian artery. Large pulses cause apoptosis of the CL
