Remember to study the hormone profiles of the estrous cycle!!!
Describe two ways that the ovary of a mare is different from other animals.
Medulla and cortex are inverted
Ovulates at ovulatory fossa
What are the 4 distinct, concentric layers of tissue found in the female reproductive tract?
Lumen - inner cavity
Mucosa and submucosa - connective tissue layers
Smooth muscle
Serosa - outer lining
Name and describe the 3 segments of the oviduct.
Infundibulum - oviduct opening, oocyte “catcher’s mitt”
Ampulla - larger first half of the oviduct packed with ciliated epithelium
Isthmus - very muscular, smaller second half of the oviduct
The _________ ligament houses the vascular supply, lymphatic drainage, and nerves, and supports the entire reproductive tract. The portion that supports the oviduct is called the _________. The portion that supports the ovary is called the ____________. The portion that supports the uterine horns and body is called the _________.
broad, mesosalpinx, mesovarium, mesometrium
List the tissue components of the uterus.
Perimetrium - outer serous layer
Myometrium - muscular layer
Endometrium - mucosa and submucosa
What is the function of the cervix?
mucus production and sperm barrier/transport
What is the function of the vagina?
copulatory organ and birth canal
During proestrus, what is happening to progesterone concentration? Estrogen concentration?
Decreasing progesterone, rising estrogen
What type of GnRH secretion pattern is observed during proestrus?
tonic
What type of gonadotropin secretion pattern is observed during proestrus?
Surge
During estrus, which hormone is at its peak concentration?
Estrogen
During estrus, what type of GnRH secretion pattern is observed?
Surge
During estrus, what type of gonadotropin secretion pattern is observed?
Surge
During diestrus, which hormone is at its peak concentration?
Progesterone
During metestrus, what is happening to estrogen concentration? Progesterone concentration?
Decreasing estrogen, increasing progesterone
During what stage of the estrous cycle are behaviors observed that indicate the female is receptive to the male?
Estrus
Which stage consists of luteinization?
Metestrus
During which stage is the CL fully functional?
Diestrus
Diestrus ends with…
luteolysis
Describe two situations in which anestrus may occur.
Female is pregnant
Female is lacking in nutrients
What are two differences between the estrous cycle and the menstrual cycle?
Estrous cycle is split 60/40, menstrual cycle is split 50/50
Menstrual cycle occurs only in primates
What stages make up the follicular phase?
Proestrus and estrus
What STARTS the follicular phase?
Luteolysis
What hormone must rapidly decline during proestrus? Why?
Progesterone, due to CL lysis and so antral follicles can mature for ovulation
Which hormone has positive feedback on GnRH and, once it reaches its threshold concentration, results in a preovulatory surge of gonadotropins?
Estrogen
Atresia
failure of follicles to develop
Which hormone stimulates recruitment and selection of follicles?
FSH
Which hormone is the primary hormone responsible for ovulation?
LH
2-cell 2-gonadotropin model
explains how ovaries produce sex steroids through cooperation of 2 cell types and 2 hormones
What are the cells and hormones of the 2-cell 2-gonadotropin model? What classification are the other 2 hormones involved?
Theca + LH = androgens*
Granulosa + FSH = estrogen*
*Steroids
Ovulation
follicle rupture and oocyte release
What changes occur in blood flow and blood vessels of the ovary and follicle prior to ovulation?
Edema (swelling) and hyperemia (increased blood flow)
What secretions contribute to breaking down connective tissue to cause ovulation?
Hyaluronic acids, collagenase
Which hormone causes contraction of the myoid (muscular) components of the ovary to increase pressure on pre-ovulatory follicles?
prostaglandin
In the female gamete, what triggers the removal of meiotic inhibitions?
LH
What are the 3 major processes of the luteal phase?
Ovulation
Luteinization
Luteolysis
What is the dominant hormone of the luteal phase?
Progesterone
What 2 major events mark the beginning and end of the luteal phase?
Ovulation and CL regression
What 2 stages of the estrous cycle occur during the luteal phase?
Metestrus and diestrus
Luteolysis
CL disintegration
Luteinization
process where theca and granulosa cells turn into luteal cells
What hormone is responsible for luteolysis?
PGF2a
What hormone(s) cause luteinization?
LH
During what stage would a CH be observed?
immediately after ovulation; proestrus
Approximately how many days does it take until a CL is fully functional?
14
Which cells develop into the large luteal cells?
Theca
Which cells develop into the small luteal cells?
Granulosa
What hormone is secreted by the luteal cells of the CL?
Progesterone
___________, secreted by the CL, has negative feedback on ___________. This inhibits secretions of ___________.
Progesterone, anterior pituitary, GnRH
Where is PGF2a produced and secreted in the female tract?
Uterine endometrium
How is PGF2a transported to the ovary?
the vascular countercurrent exchange mechanism
Why is a unique transport method necessary for PGF2a?
It would be diluted in systemic circulation and metabolized quickly in the lungs
How does the luteal cell produce progesterone?
Cholesterol imported via the LDL → transported to mitochondria, where it is converted to pregnenolone → in the smooth ER, pregnenolone is converted to progesterone
When LH binds to its receptor during the synthesis of progesterone, the downstream response…
activates several protein kinases that enzymes will use during the process
What is the difference between functional and structural death of the CL?
Functional luteolysis is a decrease in progesterone production due to a rise in PGF2a levels and less LDL and LH receptors.
Structural luteolysis is the physical breakdown of the CL; PGF2a receptor complexes open calcium channels on the CL, and the higher intracellular calcium causes apoptosis.
How does a follicle produce estrogen?
At the beginning of the estrous cycle, the hypothalamus releases GnRH, which stimulates the anterior pituitary gland to release FSH.
FSH promotes the growth of antral follicles and the subsequent development of Granulosa cells and theca cells.
Theca cells produce androgens. When stimulated by FSH, Granulosa cells will convert the androgens to estrogen, facilitated by the enzyme aromatase.
How does the LH surge lead to ovulation?
A high concentration of estrogen prior to ovulation will prompt the pituitary gland to release an LH surge into the bloodstream. This surge sends a chemical signal to the ovary that will cause it to ovulate within 28 hours.
How does the internal environment of the female reproductive tract change with estrogen dominance vs progesterone dominance?
Estrogen dominance: prepping for fertilization and pregnancy
Endometrium thickens
Cervical mucus is watery and thin to facilitate sperm movement
Increased lubrication may raise risk of infection
Progesterone dominance: maintaining pregnancy
Stabilizes the endometrium to prevent hyperplasia
Cervical mucus thickens and creates a “plug” or a “seal”
Immunosuppressive effects prevent the mother’s immune system from attacking the fetus