Female Reproductive System Physiology Flashcards
How is a cotyledonary placenta attached to the mother?
There is contact at multiple locations via button-like structures called placentomes
What side of the cotyledonary placenta attachments is the fetal side and which side is the maternal side?
The fetal side is the cotyledon and the maternal side is the caruncle
How is a diffuse placenta attached to the mother?
There is uniform attachment throughout the placenta and uterus
How is a zonary placenta attached to the mother?
There is a banded area of attachment
How is a discoidal placenta attached to the mother?
There is a distinct disc shaped region of attachment
What does the region of attachment in a discoidal placenta allow for?
Antibody transfer
How is puberty defined in females?
The first estrus
How is puberty defined in males?
The initiation of fertility following full development of accessory organs and testes
What does estrous mean?
It’s an adjective that means the period of time from one estrus to the next
Always proceeds the word ‘cycle’
What does estrus mean?
It’s a noun that means the period of time when a female is sexually receptive to the male (in heat). It signals approaching ovulation by increasing estrogen
What are monoestrus animals and what are some examples?
Animals that have only one estrous cycle per year
Some examples are foxes and bears
What are polyestrus animals and what are some examples?
Animals that have several estrous cycles per year
Some examples are pigs and cattle
What are short-day breeders and what are some examples?
Short-day breeders are sexually active in the fall or winter
Some examples are sheep, goats, deer, and elk
What are long-day breeders and what are some examples?
Long-day breeders are sexually active in the spring and summer
One example is horses
What does the word anestrus mean?
The period of inactivity in seasonally polyestrous animals
What is oogenesis?
The formation of ova
What is the role of the ovaries in oogenesis?
Theya re the source of mature female gametes and provide hormones that support ovulation and follicular development
During oogenesis what happens to primordial germ cells?
Before birth they migrate from the yolk sac to the developing ovaries and a single layer of follicular cells surrounds them
What is the central germ cell called?
Oogonium
What happens to the oogonium before puberty?
It enlarges and begins meiosis, but it does not complete meiosis, it stops at Prophase I and waits to be resumed at puberty (doesn’t develop until ready for reproduction)
What is the oogonium known as after it stops developing at Prophase I?
Primary oocyte/primary follicle
What part of other follicles is not present in the primary follicle?
Zona pellucida (there is an exception in some species)
Oocyte vs. follicle
Oocyte is the egg cell within the follicle, follicle is the cells surrounding the oocyte
What happens when the primary follicle transitions to the secondary follicle?
The oocyte gets bigger and the surrounding follicular cells replicate
What is the surrounding group of cells of the secondary follicle called?
Granulosa
What are theca cells and when do they develop?
They are a layer of stromal cells that surround the granulosa and they develop during the secondary follicular stage
What do the granulosa and theca cells do?
Change the responsiveness of the follicle to hormones based on the number of receptors they develop on their surface
What is the zona pellucida?
Protective shell provided by cross-linked glycoproteins produced from the granulosa
What type of tissue is the zona pellucida made of?
Connective tissue
Growth of what structures in the secondary follicle are independent of hormonal stimulation from gonadotropins?
Granulosa, theca cells, and zona pellucida
What structures develop receptors to what hormones?
Granulosa and theca cells of the secondary follicles develop receptors to follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
What releases gonadotropin-releasing hormone (GnRH)?
Hypothalamus
What releases FSH and LH?
Pituitary gland
What stimulates the pituitary gland to release FSH and LH?
GnRH
What produces oxytocin?
Pituitary gland
What effect does FSH have on follicular growth?
Stimulates the growth, resulting in a bigger follicle that produces more estrogen
What effect does LH have on the follicle?
It stimulates ovulation by causing the follicle to rupture and release the oocyte
Where does LH bind besides the follicle and what effect does it have there?
It binds to the corpus luteum and it causes an increase in estrogen and progesterone
What effect does LH have when it binds to thecal cells?
It causes thecal cells to proliferate and causes the production of androgens (sex hormones)
What effect does FSH have when it binds to granulosa cells?
It causes granulosa cells to proliferate and developes enzymes that convert androgens to estrogen
What do the cellular secretions of granulosa cells cause?
They accumulate and produce a fluid filled cavity called the antrum, which distinguishes it as a tertiary follicle
Describe the positive feedback loop relating to FSH, LH, and granulosa cells
The granulosa cells respond to estrogen, which causes them to develop more FSH and LH receptors. When FSH and LH bind to these receptors, more granulosa cells are produced, which starts the loop again
What is atresia?
Follicular death
What are the three stages of follicular development?
Recruitment, selection, and dominance
What stages of follicular death is atresia present?
All stages
How do follicles exist before they begin development?
They exist in a follicular nest
What triggers follicles in the follicular nest to begin growth?
A pulse of FSH
What is recruitment?
When follicles from the follicular nest begin growing
Describe the process of selection
There is low estrogen production in follicles that are selected. FSH release from the brain has a small dropoff, but there is still a low amount being released. Follicles that still respond to this low amount of FSH continue to grow and are “selected,” follicles that don’t respond don’t grow
Describe the process of dominance
Selected follicles grow at different rates and the fastest growing one dominates the others and suppresses/inhibits development of other follicles.
The dominant follicle also suppresses FSH further as well
After dominance, what is the remaining follicle called?
A pre-ovulatory follicle
What does the post-dominance follicle require to grow and ovulate?
LH
How does estrogen relate to selection?
Estrogen works to inhibit FSH secretion from the hypothalamus. Follicles that don’t respond well to the lowered amount of FSH are selected against
What process is reliant on progesterone?
Pregnancy and maintaining it
What is the corpus hemoragghicum?
Where ovulation occurs and the follicle hemorrhages to release the ovum
What does the corpus luteum do and when and why does it do it?
It produces progesterone immediately after ovulation, even if there is no fertilization or embryo implantation, to prevent the uterus from contracting in the event an embryo implants
What are inhibins and what produces them?
Inhibins are peptide hormones secreted by granulosa cells of developing follicles
What do inhibins do?
Pause further follicular development
What happens to the amount of inhibin as follicular development proceeds?
The amount of circulating inhibin increases with follicular development
What type of feedback happens where due to inhibins?
Negative feedback on the anterior pituitary gland to decrease the release of FSH
What does inhibin help to control?
It controls litter sizes so only a few follicles can mature at a time
How are estrogen and progesterone related?
Production is inversely related
As estrogen increases, what happens to the size of follicles and the amount of progesterone?
Size of follicles increases and amount of progesterone decreases
What does monotocous mean?
There is typically one offspring at a time so typically one ovum is released per cycle
What does polytocous mean?
The animal gives birth to litters so many/multiple follicles ripen at a time
What is required for ovulation to occur?
Luteinizing hormone surge
What is there a lack of in relation to the follicle after ovulation?
Follicular activity
The luteinizing hormone surge occurs in response to what?
Rapid increase in estrogen from large follicles
What happens to granulosa cells during the LH surge and what is this called?
They transform from estrogen producing cells to progesterone producing cells, which is called luteinization
What is a progesterone-producing cell called?
Luteal cell
What is a corpus hemorrhagicum?
A blood clot that forms if blood vessels rupture during ovulation
Under the influence of LH, what happens to granulosa cells that line the empty follicular cavity?
They multiply to form a corpus luteum
What is corpus luteum regression?
The apoptotic/controlled death of luteal cells
After a luteal cell dies, what replaces it and what is this called?
White connective tissue replaces it and forms a corpus albicans
If pregnancy is recognized, what is prevented?
Corpus luteum regression (luteal cell death)
